Shakespeare fortress

[rogodee]

I got one in a small lot of equipment. I know nothing about the radio, but my question concerns the pll unlock led. Is it supposed to be on all the time? It receives but has no tx. Yes I know about the caps being old, so thats a nonstarter..

 

[AudioShockwav]

I got one in a small lot of equipment. I know nothing about the radio, but my question concerns the pll unlock led. Is it supposed to be on all the time? It receives but has no tx. Yes I know about the caps being old, so thats a nonstarter..

If the Pll unlock lite is lit, it literally means that the PLL is unlocked.
When FCC changed the rules they tightened up the requirements and if you try to force the PLL to do something naughty it will unlock and kill the TX.
If it's unlocking with no alterations there is a fault.
The first thing that comes to mind is old dried out caps (I know you don't want to hear that but it is what it is) and I would recommend starting with recapping the radio .......

This is the most prevelvent cause of faults in a 45+ year old radio.

73
Jeff

 

[rogodee]

I replaced the caps on all the boards to no avail. I also swapped the pll box with the GOOD ONE from my trc 455 and no avail.

 

[brandon7861]

You say it receives. Does it receive on frequency?

No schematic for that in my collection, but I would think that if it is out of lock, it is out of lock in RX too. You may hear static, but if you give it a signal on ch1, does it receive it or is it just static?

If it is just static and RX is off frequency too, I would check for the presence of the LO signals with another radio or whatever equipment you have.

 

[rogodee]

Yes it does rx just no tx. I swapped the pll box from the fortress with the one from my 455 and no issues, so that tells me the pll is ok. Funny thing is when I removed the pll box from the fortress the led stays lit regardless if the pll box is in the radio or not. I have also recapped all the boards in the fortress. The only caps I did not replace are on the radio chassis itself and the power supply board.

 

[rogodee]

Update. I got it to rx with rx audio, but still faults on tx even with a 3rd swapped pll box from another trc 455 as well as a second swapped tx box.. ive literally replaced all of the electrolytics, ect. Im at a loss.

 

[brandon7861]

The PLL is common to both transmit and receive so if RX works, there is no need to change PLL boxes.

Without a schematic, I too am at a loss. If nobody has a schematic, whats the next closest thing with a schematic? Maybe the 455 schematic is close enough? Thats in CB-205 or CB-157