Yaesu: Yaesu 7900r not Transmitting Question

I just installed a new Yaesu 7900 in my SUV and it sound great. I’m hitting the local repeaters just fine. However I work for the sheriffs office and I am able to receive but I cannot transmit with dispatch. The Yaesu says error when I press the PTT. All of the information is entered incorrectly, as my handheld has the same exact information in it and works great. I used CHIRP to program both units using the exact frequencies, offsets, tones, etc. Any ideas of what the problem might be? Our department uses UHF.

I sure hope your department doesn’t use “70cm” as that is a ham band. Do you mean UHF?
The 7900 is a ham transceiver, and is not legal to use outside the ham bands.
The reason you are getting a transmit error is because you are trying to transmit outside the permitted and designed transmit range and the radio cpu is not allowing it.

Yes. I mean UHF. My Baeofeng operates just fine. Why is that. Sorry for newbie questions but I just got my tech license. Thus I’m trying to get everything together in one rig for my personal vehicle.

That radio will only transmit on the amateur radio bands (144-148 and 430-450 MHz) from the factory unless you modify it.
They are shipped that way because they are not FCC certified for part 90 and not legal for transmitting outside the amateur radio bands in the US.

How do I modify it and is it legal to do?

Mike082377 said:

How do I modify it and is it legal to do?

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I don't know if it can be modified or how to do it.
It is not illegal to do the mod but it is illegal to program part 90 frequencies for transmit and illegal to use it to transmit on anything but ham frequencies.

The 7900 has a transmit frequency range of 144.000 to 148.000MHz and 430.000 to 450.000MHz.
If your departments frequencies are outside that range, then the radio will not transmit there.

The Yaesu FT-7900 is an amateur radio, it does not have the FCC type certification to transmit outside the amateur radio bands.
The FCC Part 90 rules that your departments licenses is granted under strictly forbids transmitting with radios that do not have the FCC Part 90 type certification.
Using this radio on your departments frequencies and under their license puts not only yourself, but your department on the wrong side of the FCC rules. Law enforcement, fire, EMS, other public safety agencies, public works, etc are not exempt from these rules. As an amateur radio operator, your license does not give you permission to transmit outside the amateur radio bands.

To transmit on your departments frequencies, you need to have permission from the person who is directly responsible for the FCC licenses, and you need to have a radio that meets the FCC Part 90 requirements.

Your radio will work fine for amateur radio frequencies, but using it outside those frequencies runs afoul of the rules.

If you need a recommendation for a radio that will work legally on those frequencies, we'd be happy to make some recommendations.

What you are attempting is a violation of the law and your license , you can take part 90 radios to the ham band but can not take part 97 radios to part 90 , you can modify the radio to transmit out of band ,but it will void both your warranty and your F.C.C Type acceptance and if anyone takes issue with it ,you can lose your license, be subject to monetary forfeiture and potentially lose your life because usage outside the ham bands is not guaranteed and depending on the antenna used could destroy the radio or degrade your ability to communicate due to SWR mismatch , you can fire up your soldering iron and modify it via the information in the public domain available on Google.
You have been warned proceed at your own cost and peril ,many a ham has destroyed a radio by sneezing or applying to much heat to multi level surface mount boards .


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Mike082377 said:

Yes. I mean UHF. My Baeofeng operates just fine. Why is that. Sorry for newbie questions but I just got my tech license. Thus I’m trying to get everything together in one rig for my personal vehicle.

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Depends on which model you have. Some of the BaoFeng's do have Part 90 certification and can legally transmit on those frequencies. Some don't, although people will do it anyway.

I appreciate y’alls help. Go easy on a new guy. I was asking a question out of complete ignorance. I am authorized by my department to transmit but I didn’t know some radios could not do that legally. Thanks again for your help. I will just return the radio.

You're probably not authorized to transmit with a radio that wasn't issued to you or installed by the licensee.

Mike082377 said:

I appreciate y’alls help. Go easy on a new guy. I was asking a question out of complete ignorance. I am authorized by my department to transmit but I didn’t know some radios could not do that legally. Thanks again for your help. I will just return the radio.

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No problem. It can be confusing.
Returning the radio and getting your money back is a good step. If you do need to talk to your dispatch, talk to your chief about your needs. Whatever you do, make sure you get something in writing from him/her saying you are authorized to have a radio on their system in your own personal vehicle. That can pay off in the long run. The FCC rules are pretty clear on it, but unless you spend lots of time reading, you'll likely never run across them. Cover all your bases now, and then you are good to go.

If you are looking for a basic UHF mobile, there are some really good options out there. Some pretty cheap, if you don't mind going used.
And, most of them will cover the 70 centimeter amateur radio bands, too.

I work in the industry, so I got rid of all my amateur only radios years ago. I'm now running either Motorola or Kenwood commercial radios in my personal vehicles. I've got them programmed up with both work related systems as well as amateur radio frequencies. Works pretty well, and makes it easy to just have one radio in the vehicle.
Let us know if you are looking for suggestions.

Mike082377 said:

I appreciate y’alls help. Go easy on a new guy. I was asking a question out of complete ignorance. I am authorized by my department to transmit but I didn’t know some radios could not do that legally. Thanks again for your help. I will just return the radio.

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mmckenna said:

No problem. It can be confusing.

Returning the radio and getting your money back is a good step. If you do need to talk to your dispatch, talk to your chief about your needs. Whatever you do, make sure you get something in writing from him/her saying you are authorized to have a radio on their system in your own personal vehicle. That can pay off in the long run. The FCC rules are pretty clear on it, but unless you spend lots of time reading, you'll likely never run across them. Cover all your bases now, and then you are good to go.



If you are looking for a basic UHF mobile, there are some really good options out there. Some pretty cheap, if you don't mind going used.

And, most of them will cover the 70 centimeter amateur radio bands, too.



I work in the industry, so I got rid of all my amateur only radios years ago. I'm now running either Motorola or Kenwood commercial radios in my personal vehicles. I've got them programmed up with both work related systems as well as amateur radio frequencies. Works pretty well, and makes it easy to just have one radio in the vehicle.

Let us know if you are looking for suggestions.

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Hey Mike. I agree with mmckenna along the lines of what he said. Although the Yaesu will not transmit out of Amateur Radio bands, they are still great radios. I keep a Kenwood portable radio with me should it be needed for transmissions not Amateur Radio related. You would do that, or install another radio in your vehicle. It’s possible to use a removable display head and place the rest of your radio underneath your driver’s seat. I did that and placed an external speaker with it, and it works quite well with great audio.

In regards to the internet cops/Facebook lawyers, just look over them. I don’t see why folks feel the need to beat a dead horse into the ground. Once you know the limitations of what you can and cannot do with regards to radio communications and legalities, the half dozen variables really make no difference.

God luck to you and let us know if we can give you some more advice. 73!