Single band vs dual band value

[E.J.]

B'feng's website says it's part 15 certified but there's no sticker or anything on the radio itself.

 

[DaveInDenver]

I'm reading the eCFR again. I may have misremembered. It does seem kind of vague still to me since we're not talking about external amps really. But maybe it could be stretched to mean any radio can't transmit below 144 MHz without certification.

www.ecfr.gov

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§97.315 Certification of external RF power amplifiers.​

(a) Any external RF power amplifier (see §2.815 of the FCC Rules) manufactured or imported for use at an amateur radio station must be certificated for use in the amateur service in accordance with subpart J of part 2 of the FCC Rules. No amplifier capable of operation below 144 MHz may be constructed or modified by a non-amateur service licensee without a grant of certification from the FCC.​

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(b) The requirement of paragraph (a) does not apply if one or more of the following conditions are met:​

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(1) The amplifier is constructed or modified by an amateur radio operator for use at an amateur station.​

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(2) The amplifier was manufactured before April 28, 1978, and has been issued a marketing waiver by the FCC, or the amplifier was purchased before April 28, 1978, by an amateur radio operator for use at that operator's station.​

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(3) The amplifier is sold to an amateur radio operator or to a dealer, the amplifier is purchased in used condition by a dealer, or the amplifier is sold to an amateur radio operator for use at that operator's station.​

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(c) Any external RF power amplifier appearing in the Commission's database as certificated for use in the amateur service may be marketed for use in the amateur service.​

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[71 FR 66465, Nov. 15, 2006]​

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Back to Top​

§97.317 Standards for certification of external RF power amplifiers.​

(a) To receive a grant of certification, the amplifier must:​

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(1) Satisfy the spurious emission standards of §97.307 (d) or (e) of this part, as applicable, when the amplifier is operated at the lesser of 1.5 kW PEP or its full output power and when the amplifier is placed in the “standby” or “off” positions while connected to the transmitter.​

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(2) Not be capable of amplifying the input RF power (driving signal) by more than 15 dB gain. Gain is defined as the ratio of the input RF power to the output RF power of the amplifier where both power measurements are expressed in peak envelope power or mean power.​

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(3) Exhibit no amplification (0 dB gain) between 26 MHz and 28 MHz.​

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(b) Certification shall be denied when:​

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(1) The Commission determines the amplifier can be used in services other than the Amateur Radio Service, or​

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(2) The amplifier can be easily modified to operate on frequencies between 26 MHz and 28 MHz.​

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[71 FR 66465, Nov. 15, 2006]​

 

[dreadlocks]

B'feng's website says it's part 15 certified but there's no sticker or anything on the radio itself.

they recently sent a cease and desist order to AmCrest, a big Baofeng distributor specifically for the UV5R.. see: https://docs.fcc.gov/public/attachments/DA-18-801A1.pdf

 

[Billoftt]

Did you guys know that with CHIRP you can set the UV-5R and its eleventy-billion counterfeit variants to actually transmit only on the 2m and 70cm band?

 

[DaveInDenver]

Did you guys know that with CHIRP you can set the UV-5R and its eleventy-billion counterfeit variants to actually transmit only on the 2m and 70cm band?

So it's like the old VX-7R by using a software jumper to enable extended transmit?

 

[Billoftt]

It isn't done with a jumper, just software programming. If you use CHIRP to program the frequencies, go into the radio settings tabs and there is an option in there to limit the transmit range of the radio. It isn't on the same exact tab as the one to change the squelch settings, but it is in the same area. I am away form my laptop that I have CHIRP on so I can't screen shot it for you right now.

 

[Billoftt]

Here we go. Thanks for your patience, I needed to get home to my laptop I program with.
You go to the "Setting" tab. Then open the "Other Settings" menu. In there you can set the transmit limits to the radio.

 

[DaveInDenver]

Changing it in software is what I mean. It is sometimes referred to as software jumpers because they are usually not publicly documented firmware registers that change the operation of the radio. For the VX-7R people figured out the addresses and hex codes for standard, MARS/CAP and freebands to set wide band RX and TX features. When you solder and unsolder the little zero ohm jumpers they are usually toggling a bit in firmware and this is a work around so you don't have to open the radio.

 

[Billoftt]

Sorry, when I hear or read the word "jumper" I immediately think of a physical connection.

My God that looks like some nice software... Is it super simple to copy/paste a .csv file?

 

[DaveInDenver]

Jim Mitchell, KC8UNJ, wrote that software some years ago. It's called VX-7 Commander. He's written software for other radios although not much recently so either he's stopped (or gone SK, not sure) or gave up in the face of Chirp.

http://kc8unj.com

 

[E.J.]

It's cool to see that TX can be disabled on the 'fengs, I'm going to program my BF-8HP as an RX only scanner for now. I've got a Yaesu HT on the way, will get a mobile eventually just can't spend the $ on a good dual band right now.

 

[kbroderick]

It's cool to see that TX can be disabled on the 'fengs, I'm going to program my BF-8HP as an RX only scanner for now. I've got a Yaesu HT on the way, will get a mobile eventually just can't spend the $ on a good dual band right now.

It's worth noting that in addition to restricting the frequencies in the settings with CHIRP, you can also program frequencies with duplex set to 'none' to avoid accidentally keying and transmitting on a frequency you're monitoring. I'd assume you can do so through the on-radio interface, too.

 

[DaveInDenver]

It's worth noting that in addition to restricting the frequencies in the settings with CHIRP, you can also program frequencies with duplex set to 'none' to avoid accidentally keying and transmitting on a frequency you're monitoring. I'd assume you can do so through the on-radio interface, too.

Being able to set a channel to RX-only is an absolutely fundamental feature for true commercial radios. But it's unlikely something that could be easily done from the front panel because not being able to change such things in the field is often also a fundamental feature necessary to meet Part 90.

 

[ultraclyde]

As a note back to the original intent of this thread - I used my dual band mobile in the truck to crossband repeat a couple times recently. First time was Saturday, I was volunteering as a turn marshal/ traffic control person on a local triathalon. The local ham club was supporting the race with com at every turn, in the chase vehicles, at the finish line, etc. I was way out on course so I set the mobile unit up in my Jeep to crossband my HT on 70cm to the 2m net we were using for race support. Worked great for over 6 hours. Maybe 30% duty cycle.

The second time was last night on the local net. I can't clearly talk to the repeater from my HT inside the house, but the antenna on the truck has no problem, so I again crosbanded my HT on a clear 70cm freq back to the 2m net. I was able to sign in to the net and be heard with no problem. Unfortunately after about 30 min on near-constant reception it started dropping in and out, and then dropped completely. I walked out to the truck and the mobile unit was very clearly receiving but not transmitting. I turned the crossband off and tried transmitting directly to the HT on 70cm and it locked up in transmit. It kept transmitting no matter what I did until I turned the mobile unit off and back on. After that it went back to working fine. The mobile unit was really hot to the touch and had dropped the battery voltage to 11.8v. I think I pushed the cheap mobile unit beyond its capability with the constant transmitting of the Amateur Radio Hour news.

I'll have to work with it some more to see if it's a continuous problem or if it was just an overheat. Could be the cheap radio just won't handle 90% duty cycle, but I can work around that. I can alternate PL codes and set up so that the mobile unit only transmits from my HT unit onto the 2m receive freq of the repeater but doesn't transmit on 70cm. This means I'm effectively using the crossband as a wireless booster and can comply with station ID requirements as such. I can RX the 2m directly on my HT, then TX with the HT using the mobile as a booster onto the net, then flip off the PL on the HT and TX my ID without it crossbanding to the repeater and interfering with the net. (That is the most ham-nerd sentence I've ever written.) That should keep me legal for station ID.

But, to the original point, the dual band has already been useful in a way the single band wouldn't have been. So thanks for pointing me that way.

 

[DaveInDenver]

@ultraclyde, what power level were you running? The manual for my FT-8800 states that only low (5W) can handle cross band repeat. That's something people forget when they see that feature, these radios are not designed for repeater use and cannot tolerate much TX power at 100% duty cycle. Which is what you're asking it to do, it's constantly transmitting on one band or the other.