President bill fcc.. Transmits on 13mhz

[Copycat32]

Hi all Strang problem I have a president Bill fcc was working fine took it out of my care to install a bigger radio and hand this to a friend. When I went to test it it's running on 13 mhz any clues as to what I could be or just scrap it. And cal it a day?

Thank You have a great labor day weekend

 

[nomadradio]

If the 13 MHz frequency you're seeing is exactly half the channel frequency, it's the radio's PLL design. I don't have that radio's diagram handy, but a common way to simplify the PLL for AM-only CBs is to run it at half the channel frequency. This is meant to avoid problems with the final stage leaking RF energy back into the PLL. If it runs at your channel frequency, this causes "pulling", or a tendency for the frequency to wobble around with modulation. A PLL that runs at half the channel frequency is less susceptible to this quirk. A frequency doubler circuit should convert all the 13.5 MHz energy to 27 MHz. More to the point, should also filter it from escaping from inside the radio.

If someone was tweakerizing internal adjustments, maybe it could cause this?

73

 

[Copycat32]

If the 13 MHz frequency you're seeing is exactly half the channel frequency, it's the radio's PLL design. I don't have that radio's diagram handy, but a common way to simplify the PLL for AM-only CBs is to run it at half the channel frequency. This is meant to avoid problems with the final stage leaking RF energy back into the PLL. If it runs at your channel frequency, this causes "pulling", or a tendency for the frequency to wobble around with modulation. A PLL that runs at half the channel frequency is less susceptible to this quirk. A frequency doubler circuit should convert all the 13.5 MHz energy to 27 MHz. More to the point, should also filter it from escaping from inside the radio.

If someone was tweakerizing internal adjustments, maybe it could cause this?

73

Hi I purchased this new a couple years ago newer opened it till today .. Thought maybe something loose or the crystals went bad? Other then that nothing inside ro adjust only thing adjustable is power and. Audio threw software via front pannel menu..

 

[nomadradio]

And maybe I'm just out of date. Sounds like this radio is digital on the inside, if it lacks the handful of adjustments found in older designs.

73

 

[Copycat32]

And maybe I'm just out of date. Sounds like this radio is digital on the inside, if it lacks the handful of adjustments found in older designs.

73

Not sure why it was fine the next day and has been since? But trying to see if there are any audio mods for this radio..

 

[AudioShockwav]

I

Not sure why it was fine the next day and has been since? But trying to see if there are any audio mods for this radio..

I am confused
If it is tx'ing on 13 MHz I don't see how audio mods will help.
I think Bill posted a, sort of NPC mod, for this one somewhere on the forum before,
I will look when I have time.

73
Jeff

 

[Dr. Frankenstein]

@AudioShockwav

He states the radio was (working) fine the next day.

 

[AudioShockwav]

Ahh, gotcha.
I think Bill or maybe it was Tim Chambers posted something about that model, I am on the road at the moment......

73
Jeff

 

[Copycat32]

I'm not sure what happened.. But it back on frequency powered on n off checked all connections.. It seems fine now? Anyway it limits to about 50% modulation. No mater the power setting.. Mod setting is at 50 the higher it's st the lower the modulation. .. The jumper dosent do anything I can notice didn't cut the white wire can't dind a schematic