Cobra 1000 back on the bench with TX issues...

[Lkaskel]

Hey Gang,
So, I am selling this near mint Cobra 1000 and I thought I would check it out one more time before it leaves. It is a re-capped and aligned radio with no mods. The issue presents itself when you adjust L13 for 4 watts. At 2 watts it looks perfect on the scope. When you get around 2.5 watts the image starts showing carrier distortion. I did the re-align a few times to be sure that I did not miss something but, well, its not aligning right. The 1st step in the TX alignment is to adjust L17 and L16 for max on scope. L17 has NO effect what so ever. L16 does increase and decrease the output/reading on the scope (I use a meter and scope when doing a XMT alignment). When I adjust L13 it gets distorted and it will max out at 3.5 watts. One other thing, when I took a voltage measurement on the driver and final the driver was fine but the final had 19vdc on the collector. The schematic shows it should have ~12vdc. I was thinking of getting a new driver and final but I would love your thoughts.

I am having a bad covid head day so I'm going to rest some.

Thanks as always men!!!

 

[Lkaskel]

Well, its been a busy week at the bench. I put this 1000 back on the bench. All I could figure is that the driver or final are bad. The challenge was, the driver and final are extinct. They went out with the dinosaurs. Fortunately I found a post in here that said the finals in many of those older Uniden AM rigs are interchangeable. I have 2 Teaberry AM base stations that are toasted. The owner had them in a garage for years and they rusted out. I took the driver and final out of it and put them in the 1000. It now works perfectly. Yay!!!

It really is a good idea to have parts radios!!!