Voltage Oddity

[KB0PCH]

So I've been using a 9600 v5 with OpenGD77 for awhile. Recently I noticed that if I tried to transmit on high power the voltage reading would drop to under 10 volts and the radio would only put put a couple of watts of power.

I hooked up a dummy load and did some testing and found that VHF seems to be working fine, but UHF freaks out randomly. Nothing in the UHF ham band will work, but then as I get north of the ham band into GMRS range, sometimes work if I manually enter it in. If I step quickly through the frequencies in the VFO, the radio seems to put out about 20 watts on the 40 watt setting without the voltage drop, but then suddenly it will freak out again and show less than 10 volts and around a watt of output. If I manually enter in a UHF frequency that was working just a few seconds ago, it usually show the drop in voltage and low output.

I am using a cheap Chinese meter, but if I disconnect the meter (since it doesn't work with DMR) and connect to a local DMR repeater that includes the parrot talk group, when transmitting on the 40 watt setting the radios shows 9 volts and my audio playback from the repeater sounds horrible like the radio is not functioning properly (which of course, it's not).

I am using firmware 20231212155129. I tried installing an older firmware version (since I don't TX much, I don't know if this problem developed after a recent firmware update) but the same symptoms persist.

The place I purchased the radio from is willing to take the radio back, but before I go through that hassle I wanted to see if folks here had any troubleshooting ideas. I'm in the process of trying to get the radio back to the stock firmware, but since I can't find any instructions on how to do that, my process of "winging it" hasn't been going well.

Thanks!

[G4EML]

Sounds like one of two things,

Your power supply can't provide enough current. It needs to be able to provide at least 10 Amps. The current on UHF is often higher than VHF.

RF is getting into the power supply and causing it to shut down. How close is your antenna?

Colin G4EML

[SA0BUX]

Sounds like one of two things,

Your power supply can't provide enough current. It needs to be able to provide at least 10 Amps. The current on UHF is often higher than VHF.

RF is getting into the power supply and causing it to shut down. How close is your antenna?

Colin G4EML

Yes, I mostly run my 9600 in 10 W mode but I have a supply that should be able to supply around 25-30A.
I have seen more than 10A in FM at max power depending on frequency.
The pulse current in DMR is more difficult to measure.

[KB0PCH]

Sounds like one of two things,

Your power supply can't provide enough current. It needs to be able to provide at least 10 Amps. The current on UHF is often higher than VHF.

RF is getting into the power supply and causing it to shut down. How close is your antenna?

Colin G4EML

Thanks for the reply!

It is a 7 amp power supply with the antenna on the roof. Yesterday I did try putting the radio in the car wired up to what the vehicle claims is a 10amp accessory outlet and while the voltage didn't drop as far, it did drop and the power output was only a couple of watts on UHF. The antenna was a mag mount on the roof.

I just finished restoring the radio (boy, that was fun) to the stock firmware, the radio is having the same issues. I really doubted the OpenGD77 firmware was the issue, but I wanted to check the box.

I'll see about getting a bigger power supply just to be sure before sending this radio back.

[KB0PCH]

Yes, I mostly run my 9600 in 10 W mode but I have a supply that should be able to supply around 25-30A.
I have seen more than 10A in FM at max power depending on frequency.
The pulse current in DMR is more difficult to measure.

Thanks, I didn't see anything in the manual for amperage, only volts. Thanks for the reply!

[SA0BUX]

Sounds like one of two things,

Your power supply can't provide enough current. It needs to be able to provide at least 10 Amps. The current on UHF is often higher than VHF.

RF is getting into the power supply and causing it to shut down. How close is your antenna?

Colin G4EML

Thanks for the reply!

It is a 7 amp power supply with the antenna on the roof. Yesterday I did try putting the radio in the car wired up to what the vehicle claims is a 10amp accessory outlet and while the voltage didn't drop as far, it did drop and the power output was only a couple of watts on UHF. The antenna was a mag mount on the roof.

I just finished restoring the radio (boy, that was fun) to the stock firmware, the radio is having the same issues. I really doubted the OpenGD77 firmware was the issue, but I wanted to check the box.

I'll see about getting a bigger power supply just to be sure before sending this radio back.

Can you check the voltage as near as possible to the radio to verify that you doesn't have a voltage drop in the cable ?
Icom radios such as IC-7000 have problems with large voltage drop in the fuse holders due to bad holders that you need to exercise regularly.

And how is the output power when you run lower settings than maximum ?

[KB0PCH]

Can you check the voltage as near as possible to the radio to verify that you doesn't have a voltage drop in the cable ?
Icom radios such as IC-7000 have problems with large voltage drop in the fuse holders due to bad holders that you need to exercise regularly.

And how is the output power when you run lower settings than maximum ?

I was using the voltage display in the radio to determine the volts were dropping to around 9.6v when transmitting (from 13.6v when not transmitting). When I transmit on VHF the voltage does drop to around 13.1v during the transmission.

For UHF power output I get 3 watts (L), 6 watts (ML), and 12 watts (M) with the stock firmware power settings. For VHF I get 2 watts (L), 6 watts (ML), 14 watts (M), and 47 watts (H).

Thanks for the reply!

[G4EML]

Have you done a power recalibration at any time? If you have then you may have set the UHF drive level too high in an attempt to get maximum output power.

[KB0PCH]

Have you done a power recalibration at any time? If you have then you may have set the UHF drive level too high in an attempt to get maximum output power.

No, I was under the impression that the calibration features were not to be used on the 9600. I've also never tried anything related to the +W- power settings.

Thanks!

[G4EML]

OK, it was just a thought.

Colin G4EML