Yaesu/Kenwood Radios, Antenna/Antenna Location Comparison

[vtsoundman]

Thought I would share some of my recent testing with 2M/70cm radios

Prior to this test, I was/still am heavily 'invested' in Yaesu radios I own 4 Yaesu radios. I just recently picked up a Kenwood. 3 Yaesus and the Kenwoord were all purchased weeks of each other about 6 weeks ago.

This testing was done with a Jeep JK and a Sprinter Van

Read the full posting to see why I may be somewhat disappointed where my cash has gone.

Overall, the Yaesu's are a nice radio with a more updated UI (but still somewhat illogical). If robustness, TX/RX performance is more important to you, take a very hard look at Kenwood radios.

Summary Results

Antenna:

A 1/2 wave antenna offers superior performance when attempting to hit repeaters that are roughly at the same elevation or lower than current location.

The 1/4 wave vs 1/2 wave in the valleys offered little appreciable difference in performance when on the fringe. The long issued guidance of "1/4 wave in valleys to reach mountain tops vs 1/2 wave" does not seem to hold. I was able to test this with my Sprinter using two of the same radios, but with different antennas on mag mounts (effectively simultaneous testing)

A Hustler CG-144 was the clear winner. It is a co-linear 5/8 over 1/4 wave antenna resulting in a low angle radiation pattern - but it needs a ground plane and is ~7' tall. I'll use this (with a duplexer) with my TM-71A when used a xband repeater for 'mobile - base station' use in fringe applications.

Mounting Location

A 1/2-Wave Diamond 770 works EXTREMELY well when mounted just off the driver side fender on a SS mount.

Mounting on rear corners, tire carriers, license plate mount, windshield pillar mounts, all offer SIGNIFICANTLY worse performance in FRINGE applications. I tested 4 different antennas in these locations over a period of several days attempting to hit repeaters 150-300 miles away. I was on various mountain ridges in the Sierras (6500-7500') near Gold Lake surround by other mountains that were the same height or slightly higher...so some of this was line of sight and some wasn't quite line of sight.

Testing:
Antenna setup (front fender, license plate mount, tire carrier mount, center of hood with mag mount). Mounts remained stationary through testing. Antennas were moved, radio connections were moved.
Radios were directly connected via 6' of #10 to my 100aH Aux battery. Aux battery is connected to vehicle body at a seat mount. All comparisons conducted within an hour of each other (lots of permutations initially, but I narrowed it down pretty quickly).

Results did not vary significantly while the engine was running or not, solar producing full power or not (so the input voltage did not seem to matter much. While transmitting, battery voltage would drop to ~12.4-12.5V).

Testing occurred 3-4x per day - early morning, mid-day, late day, late evening.

I repeated the test with mag mounts and antennas on my sprinter. The difference in height was not really all that notable (Sprinter roof is ~9.5' tall)

One example of stark differences between radios and/or antenna location with one permutation :

FTM-100DR / Diamond 770 / Fender / full quieting into a San Jose repeater, Antenna location: Front Fender. FTM-400XDR white noise & popping, but still audible.

FTM-100DR Diamond 770 / tire carrier - could hear a San Jose repeater, but not hit it - audible, but some white noise. FTM-400DR - completely deaf.

Kenwood TM-71A / Tire carrier mount /Diamond 770. Could hit & hear the San Jose repeater off tire carrier.

Opening & closing the doors dramatically alters performance (both good & bad). Bottom line : if you need to hit a repeater/simplex and you're fringe, open & close some doors/tailgate.

Antennas Tested:
1/2 Wave Diamond770 Dual Band
1/4 Wave Comet 2m/70cm Dual band mag mount
1/4 Wave Tram 2m/70cm mag mount
5/8 over 1/4 Hustler CG-144 (monster antenna about 7' tall)

Antenna differences:
No differences in the 1/4 wave antennas

The Diamond overall did extremely well.

The Hustler was the clear winner with a reduction in white noise; more full quieting achieved, was able to hit & hear further repeaters.

Angle of antenna & ground plane significantly alters ability to hit fringe repeaters based upon position relative to nearby peaks. Sometimes you need the antenna to be tipped slightly down, sometimes slightly up.

Radio Results

Kenwood TM-71A
-True dual band radio, single antenna connection
- Consistently the best radio of the bunch for transmit and rcv capability & clarity. When asked folks to compare clarity/quality of the Kenwood vs Yaesu radios : Kenwood was consistently 'better'. No difference between FTM 100/400.
- Runs warm, but not hot during x-band operation; consistently better audio reports. 70cm power set to low.
-Least amount of bells & whistles. Interface feels archaic compared to the Yaesu radios.
- Mic is slightly heavier, buttons are far easier to press (especially one handed), Key switch feels better.

Yaesu FTM-100DR
- 2nd to the Kenwood for transmission strength and rcv sensitivity.
- Dual band, single rcv radio
- Same mic at 400; buttons can be hard to press, visibility at night is not as good at Kenwood; is smaller/lighter than Kenwood; does not have the same quality feel.
- This radio is easy to use and will be the one I install in my wife's car (she also has a ticket)

Yaesu FTM-400XDR
- True dual band, single antenna radio
- A distant 3rd for transmit & rcv capability.
- Frequently out-talked itself. Consistently could not rcv as well as any of the other mobile units. I had two different 400XDRs (one in my Sprinter and one in the Jeep) and the results were the same. Not believing the results, I swapped them on a couple of occasions to see if it mattered - it did not.
- Runs very hot as x-band repeater. 70cm power set to low. At one point, concerned the unit may shut down.
- APRS consistently does not function as well as the FTM-100DR or Kenwood TM-71A w/ Mobilink APRS. Transmit intervals appears somewhat random even when set for fixed operation - (not small variations either).

- Of note : I had one 400XDR fail within 1-2 days out of the box. (I own 3 FTM-400XDRs). Some HRO stores have good customer service, some have crappy. I am a huge fan of the Anaheim store and not so much of my 'home' store, Oakland.

HTs Tested

Baofeng UV-5r w/ 6" or 18" Nagoya
- Nice solid little radio; dates from 2014/2015
-Crappy menu system, difficult to program

Baofeng GT-3 w/ ~6" Nagoya
- Supposedly later gen than the UV-5r. Not seen/heard/felt a difference between 5r and GT-3
- Popping consistently noted
- I've had 2-3 fail in various ways over the years (Mostly 2M fails)
-Crappy menu system, difficult to program

Baofeng UV-8HP w/ Nagoya ~18" antenna
- Best rcv and transmit; best battery life.
- No difference in audio reports (at full quieting) between the Baofengs.
-Crappy menu system, difficult to program

Yaesu FTM-70D w/ SRH77CA ~18" antenna
- Relatively poor battery life when compared to the Baofeng units when configured the same (dual watch off, scanning off, etc). The Yaesu battery life gets downright abysmal when more features are turned on.
- Rcv sensitivity is slightly better than the 8HP.
- Purchased the radio with the hopes of getting a 'real' radio. Overall, somewhat disappointed. Would not spend money on it UNLESS you want C4FM (Fusion).
- Consistently did not sound 'as good' as the Baofengs, a but more hollow is how it is described
- Very easy to use relative to the Baofeng radios.

 

[Billoftt]

Nice test. I purchased a second-hand TM-V71A as my first mobile radio so I never knew how it compared to the others. It is refreshing to know I made a good choice. I kinda want the Icom ID-5100A becuase of its sexiness, but I am not sure it is going to actually give me anything more than what I already have other than the digital modes and the automatic repeater finder.

 

[DaveInDenver]

Did you tune (or at least check tuning of) the antennas between tests when you moved them? If the tune is off just a little you might be significantly less efficient at both TX and RX. Generally modern radios are all going to be about as sensitive, the antenna is the make-or-break difference. Although the robustness of the various radios will differ, e.g the ability to deal with close in simultaneous signals can make a major difference. You can glean some of this from their IMD. In the backcountry this shouldn't matter but in town it may need to be factored in. The TM-71A is a pretty good radio, no argument there. It does not surprise me that it outperformed the FTM-100 & FTM-400.

One thing to note is the Kenwood you tested is a purely FM radio while the two Yaesu radios are FM and digital. This shouldn't matter in theory but my experience is it does. The same thing is true of my Motorola & Vertex Standard DMR and a Connect System DMR radios I have. Their analog capability is slightly poorer than an analog-only radio. My FT-8800 and an older CM300 both are noticeably better than the Vertex Standard VXD7200 mobile I have on FM. The reason for this is older purely analog radios were pretty much dialed in by the 1990s and 2000s. The newer dual mode radios rely more on software to modulate and demodulate and the state of the art is still a ways away.

So the flip side here is when you use a FTM-100 on Fusion the range and clarity will improve. At least until it doesn't, which is generally very abrupt. It does make a difference with an HT. The range and battery life will improve with digital modes, if you can live with the inelegant fringe performance.

 

[vtsoundman]

Nice test. I purchased a second-hand TM-V71A as my first mobile radio so I never knew how it compared to the others. It is refreshing to know I made a good choice. I kinda want the Icom ID-5100A becuase of its sexiness, but I am not sure it is going to actually give me anything more than what I already have other than the digital modes and the automatic repeater finder.

Most hams I've spoken to have said the Icom 2m/uhf is not as good as the Kenwood Radios and intermod is worse....however, most hams have also told me about the 1/4 vs 1/2 wave stuff and that Yaesu/Kenwood were interchangeable... It all depends on who you know (if they are on DSTAR) and who you know. The 5100 was immediately ruled out as it does not have proper APRS.

Did you tune (or at least check tuning of) the antennas between tests when you moved them? If the tune is off just a little you might be significantly less efficient at both TX and RX. Generally modern radios are all going to be about as sensitive, the antenna is the make-or-break difference. Although the robustness of the various radios will differ, e.g the ability to deal with close in simultaneous signals can make a major difference. You can glean some of this from their IMD. In the backcountry this shouldn't matter but in town it may need to be factored in. The TM-71A is a pretty good radio, no argument there. It does not surprise me that it outperformed the FTM-100 & FTM-400.

One thing to note is the Kenwood you tested is a purely FM radio while the two Yaesu radios are FM and digital. This shouldn't matter in theory but my experience is it does. The same thing is true of my Motorola & Vertex Standard DMR and a Connect System DMR radios I have. Their analog capability is slightly poorer than an analog-only radio. My FT-8800 and an older CM300 both are noticeably better than the Vertex Standard VXD7200 mobile I have on FM. The reason for this is older purely analog radios were pretty much dialed in by the 1990s and 2000s. The newer dual mode radios rely more on software to modulate and demodulate and the state of the art is still a ways away.

So the flip side here is when you use a FTM-100 on Fusion the range and clarity will improve. At least until it doesn't, which is generally very abrupt. It does make a difference with an HT. The range and battery life will improve with digital modes, if you can live with the inelegant fringe performance.

I don't have a antenna tuner/analyzer, just an SWR meter - which I did check to minimize SWR on each mount (I have several diamond 770 antennas and not surprisingly, I didn't have to adjust them much at all).

The highest SWR was the hustler antenna at just over 1.3...but it didn't seem to matter. I played with the adjustment screws and changed the whip length, but couldn't get it any lower. I suspect the mag mount had something to do with it.

I thought digital would have a poorer range than analog on fringe? There are so few repeaters using any of the digital modes, that in back country travel, it hardly makes any sense (Nevada excluded...seems to be moderate coverage there).

I'll be trying this with HF in the next year or so...testing longest simplex possiblities...

Forgot to mention - I bet a pre-digital Yaesu and a Kenwood are more comparable than the 100/400 to the 71A. I think your 7700 is from the same vintage as the v71A.

However, I spoke to a friend of mine on the east coast - he and his buddy picked up a pair of the new 80w 2M Yaesu 2980R. Both have solid 2m 1/2 antenna setups on their trucks. The 2980 out talked itself more than a few times and wasn't really that much better (if at all) than their old kenwood 281a (65w 2m). I was looking at the 2980r pretty closely for fringe simplex duties, but now, I don't know....

While 15W difference isn't much, the Yaesu's 2980's radio rcv capability seems to be inferior to the 281a (in at least one instance they mentioned the 281a could rcv the 2980r, but the 2980 was deaf).

 

[DaveInDenver]

I thought digital would have a poorer range than analog on fringe?

You have to define what you mean about range and fringing to make a comparison. What we're talking about is the region where the signal to noise starts to become an issue. With FM there's a hard threshold where a signal can no longer be detected and it's just open squelch. Generally speaking there's always a distance where an analog signal is weak and understanding the other station becomes increasingly difficult. On an FM (or AM, SSB) radio that's obviously subjective to each of us.

When you go digital the radio is demodulating the signal as a series of pulses, frequencies or levels. It's similar to listening to CW actually. And in the same way the radio only needs to hear a change in the signal that it understands as a valid bit. And just like analog CW the radio with an adept operator a digital receiver can hear weak signals really deep into the noise. IOW, there's a very small SNR necessary to demodulate information with digital modes. Think about WSPR and JT65. You can have hundreds of mile paths at sub one watt power levels and get messages through and to naked ears the whole thing just sounds like white noise. That is a much lower bit rate than DMR and Fusion, but the principle remains, that what's in the noise isn't all random.

The problem is when it can't the information received goes from 100% to zero. With analog modes there's a lot of advantage to 50% copy but my experience is that digital modes work practically to a greater distance than analog. IOW, there's very little drop out in the increasing static region and when the DMR radio begins to drop out a lot is where you'd have the squelch open and need to be concentrating on the FM radio, too. Unless it's a real dire situation where copying someone is critical I just prefer the digital radio.

But this question of life-or-death is something firefighters and cops had to deal with when digital radios first started showing up under the FCC narrowband mandate. So it's something that radio manufacturers know about and work on minimizing, which is why the analog functionality is just for backwards capability rather than being something of high development importance like error correction. If there's one thing about digital radio it's that multipath seems to really be it's Achilles. Otherwise I can hold digital repeaters longer than I can analog. But like I've said, I haven't done extensive A-B testing and since my radio is DMR with an analog after thought I wouldn't expect it to perform well on FM either.

Point is, though, if you're going to buy a radio for analog modes you will be better served buying one that is analog, like the TM-V71. It really is a very good radio. Having a real analog front end, in particular a real IF mixer and discriminator with a true analog squelch, helps tremendously.

BTW, doesn't surprise me to hear an FT-2980 is slightly harder of hearing. It's receiver is only rated at 0.4 uV while the ARRL tested the TM-V71 at 0.15 uV on 2m. My old FT-8800 was more similar to the Kenwood, rated for 0.2 uV 12 dB SINAD. Going from 0.4uV to 0.15uV is about 6 dB difference in sensitivity. The ARRL lab, though, tested the old FT-2900 at 0.2 uV. Also there's the possibility of rejection, intermod or perhaps production variance here, so sensitivity isn't the only factor.

Even assuming the receiver on the Yaesu really is a bit more deaf coupled with the extra power it's not hard for me to believe it might out talk itself. Going from 65 to 80 watts should represent a theoretical TX range improvement of about 10% (it's about about 1 dB). IOW, assuming all other things equal going from a TM-V71 to the FT-2980 would mean your turn around needs to have as much as +7 dB (but more likely more like +3 or +4 dB) more signal strength for a fully balance duplex path. Nice thing here is that if you want more balanced TX/RX you can turn the FT-2980 down to 50 W and it shouldn't out talk itself. Then if you ever find yourself in a situation where you can happen to copy a weaker station but they can't hear you back you can set your power to 11. Or you can run a 1/4 wavelength antenna instead of one with gain. That's a couple of dB difference in radiated power.

So you have to be fair here, the differences you're talking about are at the margins in a very quiet RF environment. So inferior is harsh. A lot of people for many, many years have run the FT-29xx radios (which all have the same receiver AFAIK) successfully and happily. Say you have an FT-2980 on both ends the extra TX power to some extent will balance out the less sensitive RX and parity is achieved. Anyway, the FT-2900 and it's successors are a pretty common radio within ARES and RACES circles because they are bulletproof mechanically and electrically and highly immune to interference.

Sometimes there's more to a "good" radio than just strictly lab numbers or specifications. The most sensitive receiver is useless if a signal less than 50 KHz away upsets it. This is a common issue with ham radios. They have become so sensitive and wide banded that you almost have to be on top of another station for it it to make it past the rejection filters. It's particularly important in an urban environment or if your AREAS station is co-located at a sheriffs office or fire station that other radios don't create problems for yours. Having 3 dB of better sensitivity is gone in a flash if you end up with 8 or 10 dB of de-sense due to a close in station or a harmonic from someone's cell phone or PC or whatever.

 

[vtsoundman]

You have to define what you mean about range and fringing to make a comparison. What we're talking about is the region where the signal to noise starts to become an issue. With FM there's a hard threshold where a signal can no longer be detected and it's just open squelch. Generally speaking there's always a distance where an analog signal is weak and understanding the other station becomes increasingly difficult. On an FM (or AM, SSB) radio that's obviously subjective to each of us.

When you go digital the radio is demodulating the signal as a series of pulses, frequencies or levels. It's similar to listening to CW actually. And in the same way the radio only needs to hear a change in the signal that it understands as a valid bit. And just like analog CW the radio with an adept operator a digital receiver can hear weak signals really deep into the noise. IOW, there's a very small SNR necessary to demodulate information with digital modes. Think about WSPR and JT65. You can have hundreds of mile paths at sub one watt power levels and get messages through and to naked ears the whole thing just sounds like white noise. That is a much lower bit rate than DMR and Fusion, but the principle remains, that what's in the noise isn't all random.

The problem is when it can't the information received goes from 100% to zero. With analog modes there's a lot of advantage to 50% copy but my experience is that digital modes work practically to a greater distance than analog. IOW, there's very little drop out in the increasing static region and when the DMR radio begins to drop out a lot is where you'd have the squelch open and need to be concentrating on the FM radio, too. Unless it's a real dire situation where copying someone is critical I just prefer the digital radio.

But this question of life-or-death is something firefighters and cops had to deal with when digital radios first started showing up under the FCC narrowband mandate. So it's something that radio manufacturers know about and work on minimizing, which is why the analog functionality is just for backwards capability rather than being something of high development importance like error correction. If there's one thing about digital radio it's that multipath seems to really be it's Achilles. Otherwise I can hold digital repeaters longer than I can analog. But like I've said, I haven't done extensive A-B testing and since my radio is DMR with an analog after thought I wouldn't expect it to perform well on FM either.

Point is, though, if you're going to buy a radio for analog modes you will be better served buying one that is analog, like the TM-V71. It really is a very good radio. Having a real analog front end, in particular a real IF mixer and discriminator with a true analog squelch, helps tremendously.

BTW, doesn't surprise me to hear an FT-2980 is slightly harder of hearing. It's receiver is only rated at 0.4 uV while the ARRL tested the TM-V71 at 0.15 uV on 2m. My old FT-8800 was more similar to the Kenwood, rated for 0.2 uV 12 dB SINAD. Going from 0.4uV to 0.15uV is about 6 dB difference in sensitivity. The ARRL lab, though, tested the old FT-2900 at 0.2 uV. Also there's the possibility of rejection, intermod or perhaps production variance here, so sensitivity isn't the only factor.

Even assuming the receiver on the Yaesu really is a bit more deaf coupled with the extra power it's not hard for me to believe it might out talk itself. Going from 65 to 80 watts should represent a theoretical TX range improvement of about 10% (it's about about 1 dB). IOW, assuming all other things equal going from a TM-V71 to the FT-2980 would mean your turn around needs to have as much as +7 dB (but more likely more like +3 or +4 dB) more signal strength for a fully balance duplex path. Nice thing here is that if you want more balanced TX/RX you can turn the FT-2980 down to 50 W and it shouldn't out talk itself. Then if you ever find yourself in a situation where you can happen to copy a weaker station but they can't hear you back you can set your power to 11. Or you can run a 1/4 wavelength antenna instead of one with gain. That's a couple of dB difference in radiated power.

So you have to be fair here, the differences you're talking about are at the margins in a very quiet RF environment. So inferior is harsh. A lot of people for many, many years have run the FT-29xx radios (which all have the same receiver AFAIK) successfully and happily. Say you have an FT-2980 on both ends the extra TX power to some extent will balance out the less sensitive RX and parity is achieved. Anyway, the FT-2900 and it's successors are a pretty common radio within ARES and RACES circles because they are bulletproof mechanically and electrically and highly immune to interference.

Sometimes there's more to a "good" radio than just strictly lab numbers or specifications. The most sensitive receiver is useless if a signal less than 50 KHz away upsets it. This is a common issue with ham radios. They have become so sensitive and wide banded that you almost have to be on top of another station for it it to make it past the rejection filters. It's particularly important in an urban environment or if your AREAS station is co-located at a sheriffs office or fire station that other radios don't create problems for yours. Having 3 dB of better sensitivity is gone in a flash if you end up with 8 or 10 dB of de-sense due to a close in station or a harmonic from someone's cell phone or PC or whatever.

Thx for the great response...It has been a while since I played with (aka analyzed) comms (I'm a power electronics engineer). So by fringe & range, I mean total distance between transceivers - before the radio drops squelch/becomes garbled.

Good point on the dedicated analog vs mixed digital radios - I guess I would have expected the performance of the 100/400 to be closer than it was during the A/B/C testing.

I haven't read enough about Fusion / DMR to know how robust/resilient the various protocols are to lost bits. My impression was that it needed a greater SNR than analog in for ham applications, but your post suggests otherwise. The issue is still a lack of repeaters...

I've noticed that adjacent Yaesus radios receiving 2M (within a few tens of feet) are often 'muted' during APRS and other 2M transmissions. I haven't noticed if my v71a was doing the same thing.

The FT-2980 hasn't been out that long...have you had any field time with it? I'm curious as to your thoughts if I should get the Kenwood TM-281A or the FT-2980 for dedicated 2M rigs. Turning down the 2980 from full power somewhat defeats the purpose...why not get the TM-281A with its better stats (I think same rcv as V71a, but with 15W more 2M power)?

At some point in the near future, I'll be picking up a HF radio as well - the Yaesu FT891 has a great form factor. Do you have any experience with it or other HF radios? The ICOM 7100 has a semi-decent form factor for mobile use, but it is an older radio - so I don't know how good its DSP is relative to the newer radios.

 

[DaveInDenver]

The HF radios I've owned are the Yaesu FT-817ND, FT-857D, FT-950, FTdx-1200, the Icom IC-7000 and an Alinco DX-70. I still own the FT-857.

I only owned the FTdx-1200 briefly, very little time on it. I had the FT-817 for a few years to operate QRP but found that the FT-857 I already had (it was mounted for a short time mobile with an ATAS-120) has fairly similar performance and I didn't need to carry a linear amp (I'd home built a little 35 watts multi band amp for it). The 857 only draws about twice the power on RX compared to the 817, but don't think that's a complement, it's about 1500 mA. The 817 is a power hog relatively. But it's a fun, interesting little radio. Neither are really all that light and small for hauling around (compared to a tin can 40m), so I just run the FT-857 portable.

I owned the FT-950 for several years and I really liked that radio. Sold it with it's FC-40 for an IC-7000 and AH-4 when we downsized to a smaller house. I did not like the IC-7000 at all. It was a very sensitive but awful rejection. Also the audio to my ears was harsh even compared to the FT-8x7 radios. My FT-857 has add-in 2KHz and 600 Hz filters in it and those worked as well as the IF DSP of the IC-7000 in the same location. I do still miss my FT-950, that was a nice sounding, easy to use radio. The Alinco I got in a trade. I should have kept that radio I guess, it worked with the AH-4 I have (and still use with the FT-857 with a home-brew adapter).

I'd really like to someday get an FT-891 or FT-991. I understand they do OK for what they are. The IC-7000 form factor was nice, that I did like about it. And the FT-891 is very similar in size and shape.

 

[DaveInDenver]

I haven't read enough about Fusion / DMR to know how robust/resilient the various protocols are to lost bits. My impression was that it needed a greater SNR than analog in for ham applications, but your post suggests otherwise. The issue is still a lack of repeaters...

DMR, really all digital, seems to be regional. Here in Colorado we have several prominent DMR repeaters, very few places that aren't covered yet. It's still distant to FM for sure but as far as having access to linked repeaters it's pretty good.

Motorola quotes for the XPR4550 a 5% bit error rate at 0.3uV (-118 dBm) but I don't know what FEC they do to compensate. So it's specified (0.3uV) the same as their 12dB SINAD. It's not really a 1:1 comparison on numbers though.

The FT-2980 hasn't been out that long...have you had any field time with it? I'm curious as to your thoughts if I should get the Kenwood TM-281A or the FT-2980 for dedicated 2M rigs. Turning down the 2980 from full power somewhat defeats the purpose...why not get the TM-281A with its better stats (I think same rcv as V71a, but with 15W more 2M power)?

Never have owned an FT-2900 or FT-2980. I think running a comparison strictly on sensitivity is probably not a complete analysis. Kenwood makes a good radio, as do Icom, Yaesu, Alinco, Motorola, Hytera. But which performs best is going to depend on too many things outside of an RF lab. If your testing is indicating the TM-281 works for you in your situation and environment then go with it, I doubt you'll be happy if you don't. I've had Kenwood (a TM-261) and worked fine. If I was buying an analog radio right it probably would be a Kenwood to be honest. But I can't say I've ever felt limited by a FT-8800 or anything else I've owned. Hams are like pickup guys, we like to brand bash. I don't think it's fair, they're all pretty good radios now.

To tell the truth the only time I really go for distance on VHF is SOTA and then I'm using my FT-857 and a Yagi. Otherwise we usually run into terrain issues before we run strictly out of RF range. Most recent time I can think of I tested it was being able to open a repeater above Craig, CO, that was about 60 miles from camp above of Dinosaur National Monument. Both I and the repeater were high in elevation, so clear line of sight. That was with my Larsen 2/70 (open coil) and Connect Systems CS800D on FM and only needed low power as I recall.

You're supposed to turn the power down to the lowest needed to hold the channel. But like I mentioned adding 15 or 30 watts can be the same as going to a higher gain antenna, so it's just a numbers game. Like CPU clock speed or horsepower, bigger has to be better.

I've noticed that adjacent Yaesus radios receiving 2M (within a few tens of feet) are often 'muted' during APRS and other 2M transmissions. I haven't noticed if my v71a was doing the same thing.

Are you saying the Kenwood doesn't de-sense with an APRS station transmitting next to it? My FT-8800 did go mute in those conditions, but I had the antennas about 2 feet apart and that's a brutal thing to do to a radio, even if it's only 5 watts. It would really surprise me if the Kenwood doesn't also de-sense at least. There's just no way to defeat physics here when you put one radio in the near field of a transmitting antenna.

 

[vtsoundman]

f your testing is indicating the TM-281 works for you in your situation and environment then go with it, I doubt you'll be happy if you don't.

I haven't tested it yet - just a buddy back east that was did some VHF simplex comparisons...(the FT2980r & TM-281).

Are you saying the Kenwood doesn't de-sense with an APRS station transmitting next to it? My FT-8800 did go mute in those conditions, but I had the antennas about 2 feet apart and that's a brutal thing to do to a radio, even if it's only 5 watts. It would really surprise me if the Kenwood doesn't also de-sense at least. There's just no way to defeat physics here when you put one radio in the near field of a transmitting antenna.

No - just didn't notice if it did or did not de-sense/go mute at the time. I killed APRS once I was stationary for a while..and while doing most of these tests. Next time I'm in the van I'll give it a whirl.

And I was trying to figure out why the Yaesu wasn't transmitting the APRS beacon per my settings (still haven't figured out why it doesn't...)

 

[DaveInDenver]

Got it I think. You'll have to explain what's going on with APRS when you have details. The TM-V71 has the same body as the TM-D710 so maybe it has the ability to switch for APRS or perhaps have some logic built in that's making it operate differently. I can't imagine why a regular single band radio when you connect the audio in/out and PTT to a TNC would fail to operate. It should either work or not. There's other possibilities. For example, I've had cases where a TNC would lock up due to RF interference from being too close to the radio when it transmitted or the keying function or levels are wrong (like how sometimes PTT and mic are combined on HTs).

 

[vtsoundman]

The V71a does not have APRS - I use mobilink, a small APRS device connected via Bluetooth to APRSDroid....it works great. Does everything I need it it too. The mobilink is connected to the V71a via a data cable into the back of the radio and uses TNC.

The issue seems to be with the APRS in the Yaesu 100/400. They have Smart Beaconing (Combo of speed, direction change, time), proportial (speed), and manual (time).

Manual, can be set to beacon every 30sec or at some random time.

Proportional and Smart Beaconing rarely works as advertised/described in my experience. It works fine for crusing around town, but becomes wildly inconsistent if you're using it on trails.

The same can be said for the Manual settings - there are times when it will be several minutes before I'll see a beacon from my Yaesu radios when they are set to ping every 30s (this is with logging on the mobilink) and another radio looking for packets from my station. I'm not sure yet if it user error or an actual bug. I've seen mixed reports on forums about this. (Side note: yaesu doesn't really allow full TNC into the radio)...

 

[Hillbilly Heaven]

It maybe that at the time of beaconing the freq is busy. I don't know if Yaesu holds the beacon command or if it is just skipped till the next beacon time. I have run into some trackers that will not beacon if the freq is busy and just skips that beacon.

 

[DaveInDenver]

The V71a does not have APRS - I use mobilink, a small APRS device connected via Bluetooth to APRSDroid....it works great. Does everything I need it it too. The mobilink is connected to the V71a via a data cable into the back of the radio and uses TNC.

I may not have been clear. The TM-V71 and TM-D710 share the same main body, the APRS stuff is I know contained in the head (you can upgrade a TM-V71 to a TM-D710 by buying the face). But the transmit switch would be in the body, the relay or however Kenwood does it, to switch the transmitter between main and secondary VFO when an APRS packets needs to be sent.

The issue seems to be with the APRS in the Yaesu 100/400. They have Smart Beaconing (Combo of speed, direction change, time), proportial (speed), and manual (time).

Manual, can be set to beacon every 30sec or at some random time.

Proportional and Smart Beaconing rarely works as advertised/described in my experience. It works fine for crusing around town, but becomes wildly inconsistent if you're using it on trails.

The same can be said for the Manual settings - there are times when it will be several minutes before I'll see a beacon from my Yaesu radios when they are set to ping every 30s (this is with logging on the mobilink) and another radio looking for packets from my station. I'm not sure yet if it user error or an actual bug. I've seen mixed reports on forums about this. (Side note: yaesu doesn't really allow full TNC into the radio)...

It is true, the Yaesu radios don't have a full general purpose TNC. I've only ever owned an FTM-350 for Yaesu radios with built-in APRS. It does what it's advertised to do, APRS on the side, receive and send messages. It can output NMEA data (I used the Argent GTRANS with a Nuvi 350, so that should tell ya how long ago that was). But, no, it's not the same as the TNC in a TM-D710 or external. I do recall that it would skip beacons if the main side was transmitting at the time. I don't know if it tries again immediately or just drops that beacon on the floor for good. I suspect it's just a lost beacon. I don't know why that would trip up. My recollection was that if you're actively receiving the radio would still blank and the beacon would transmit. It was only if the APRS side couldn't get the TX key that it would drop the beacon.

AFAIK the FTM-400 works the same way but the FTM-100 is a little different beast. It's only a single VFO so the APRS on it is more like a dual watch with APRS as priority. If you're using the radio to actually talk I'm not sure how it would work. It can't simultaneously listen on 2 frequencies and it would have to actually change the VFO to do a beacon. I get the impression that FTM-100 APRS is more that it's an APRS radio that lets you monitor a frequency for activity. Then if activity is heard it becomes primarily a voice radio.

My main APRS station is a Argent Tracker3 stuffed inside a 5 W data radio. On that Smart Beaconing works fine for me. Parameters I use are low speed of 5 MPH transmit at 300 sec intervals up to fast speed of 55 MPG transmit at 75 sec intervals using a turn of 28 degrees and never more than 60 seconds. This gets a beacon about every 2 or 3 minutes on average. Which I do have set to skip one beacon if it hears itself and listen for activity. So that might stretch intervals in town if there's digipeaters or several stations. On the trail I move my beacon to a different time slot, looks like I have it set to 10 seconds to reduce top of the minute collisions with other beacons.

I have a TNC-X that I'll use at home and I have a TinyTrak 4 that I used to use with a FT-1500 and now it's connected to a VX-7R. That TT4 is somewhat inconsistent but it's been so long since I configured it couldn't say if it's using Smart Beaconing or what. The TNC-X doesn't beacon itself, it's just a fixed location modem and Xastir drives it. I have an old Motorola CM300 that I use as a data radio for that.

 

[vtsoundman]

@DaveInDenver - You said something interesting:

Then if you ever find yourself in a situation where you can happen to copy a weaker station but they can't hear you back you can set your power to 11. Or you can run a 1/4 wavelength antenna instead of one with gain. That's a couple of dB difference in radiated power.

Can you explain this a bit? I was under the impression that ERP & gain were positively proportional - but does your comment suggests interplay of something else?

Is the radiation angle of the 1/4 wave vs 1/2 wave the true issue? The 1/2wave have a larger lobe at a lower elevation? (And following this logic, is why the Hustler, a 5/8 over 1/4 collinear was so good - a claimed gain of 5.2dBi + a large lob at a relatively low radiation angle...)

I'm trying to correlate antenna theory back to my 'test' results. I found the 1/2 wave antenna routinely hit distant repeaters at my altitude (varied between 6000 - 7500ft) whereas the 1/4 wave was completely ineffective (too bad I didn't have a 5/8 with me). In a few instances, the distant repeater was significantly lower, and tilting the 1/2 wave Diamond 770 or Hustler AND its associated orthogonal ground plane (AKA the hood) towards the repeater improved strength & clarity.

It would be really interesting to have tested a 0.64 wavelength antenna too...

 

[DaveInDenver]

Everything is compared back to a measurement of an isotropic antenna, which is a theoretical radiator that is imagined like a point source with a perfect sphere with an equally dense field in all directions.

It's impossible to realize this practically and the closest we can actually build to a 1/2λ dipole. In free space with no external influence (e.g. many wavelengths over ground, etc.) it will look like a sphere with the ends dimpled. The pattern is slightly irregular and you can show mathematically that in an axis along it's main lobe the field strength has a magnitude 2.15 dB greater than the isotropic ideal. But you'll notice that in some axis the field strength is the same or less all the way to zero longitudinally on the antenna. That's to say the amount of signal radiated off the ends of a dipole is practically zero. We define this as the antenna's gain and assigned it the unit of dBi or decibel relative to isotropic and the total envelope power is the same in both.



The additional problem is it's very difficult to construct and use a 1/2λ dipole stationary without influencing it and basically impossible to do so mobile.

If you cut a dipole in half and put one of the 1/4λ leg over a counterpoise the radiated pattern will be one half of the dipole and the other half of the dipole is reflected in the counterpoise. Everyone calls it ground but that's not really right, it's a return path not ground. It's the same precise technical term you and I have to use in circuits.

In any case, it'll have the same gain, 2.15 dBi. The patterns in elevation and azimuth will be the same, big fat bulbous doughnuts. The angle of middle of the main lobe, which is defined as the antenna's take-off or elevation angle, is where you measure the gain.

Since we live in reality the lowest gain we'll ever have is that of a 1/2λ dipole or 1/4λ monopole. So that is usually defined as the dBd or decibels relative to the assume 1/2λ dipole. it's always possible to relate dBi to dBd with the 2.15 dB correction. A 1/4λ whip is 0 dBd.




The benefit to a 1/2λ dipole or 1/4λ monopole is the feed point has a natural impedance of 37 ohms, which mades it easy to match to a 50 ohm output impedance. These are originally all arbitrary, there's no reason radios had to be made with that output impedance but it was settled on practically.

When you change the antenna's length electrically (which may or may not be physically since you can trick things with coils and cap) you get different radiation patterns. This puts more energy into smaller lobes, which we see as increasing gain of an antenna. You always have the same power being delivered to the antenna feed point but with increasing gain more energy is focused into small regions. You are losing energy in places there are no lobes. This is called directionality of an antenna.



So you can see as wavelength increases you focus more energy and eventually get very off patterns that really aren't of much benefit anymore. But it's important to see that as gain and directionality increase where the lobes end up moves up and down in elevation. This is a critical point, a 1/4λ antenna has a fairly high take off angle, it really doesn't favor any one direction but is only really deaf 90 degrees. But just a few degrees down it's going to work pretty much the same.

When you go to say a 1/2λ monopole you'll see you focus significantly more energy into the main (sole) lobe but it's got very little once you get not that far off the take off angle. Go to a 5/8λ and you start to see a second lobe form.

Since there's only criticality to 1/4λ and 1/2λ when you change to a different lengths the impedance changes. So before you start thinking gain is free (assuming you don't care about directionality) you have to transform the impedance from 50 ohms to the new feed point impedance. In the case of a 1/2λ the impedance is VERY high, a couple of thousand ohms.

The reason for all this is what our EM Fields taught us about us about the incident wave and reflections. You're blunting the end of a transmission line and setting up a standing wave on the antenna. Which when you hit resonance radiates energy in the E- and H-fields just like a light bulb does light or sound from a critically tuned string. A 1/2λ monopole is like feeding a dipole at a current null but a voltage maximum or the equivalent of a 1λ dipole.

ERP is defined as Effective Radiated Power. So it's the signal strength that you radiate from your antenna in the main lobe or lobes. So if you're putting RF power into an antenna a field of some strength is created. You can estimate that by saying you're producing 50 watts (16.99 dBW, decibel-watts, it's the measure against a 1W reference) plus the gain of the antenna. That means your 16.99 dBW transmitter into a 1/4λ antenna produces 16.99 dBW ERP or 19.14 dBW EIRP (Effective Isotropic Radiated Power). Just like claimed gain you have to watch if it's being measured in dBi or dBd. The reference is against the real baseline antenna, thus ERP. But EIRP is useful too, just remember to use the 2.15 dB correction.

Say you have a 1/2λ whip with a claimed gain of 5 dBi or 2.85 dBd. The ERP of this with a 50 watt transmitter is 16.99 + 2.85 = 19.84 dBW, which creates the same field along its main axis as though you had you put 96 watts into a 1/4λ antenna. But realizing that in regions outside the lobe it's as though you put less than 50 watts all the way down to zero in a significant region.

Gain and ERP are positively proportional. They are absolutely interconnected, can't estimate ERP without knowing gain. The key is what they mean, like you see the radiation pattern becomes important to know. When you starting doing field strength calculations you have to know the radiation pattern and ERP to know field strength coverage.

When you start stacking elements the situation becomes more interesting (some may say confusing). Since the elements don't operate independently in the near field they will further strengthen some lobes and cancel others. A stacked element antenna can produce a fairly strong field without needing a Yagi or dish.