[Boatanchors] CE-200V progress/problems - Status update 6/03/10

[Paul]

Finally got back to work on the CE-200V this weekend (my weekend is Tues/Wed due to my work schedule). Too hot to work outdoors so decided to spend some time in the cool shack.
 
When I last left the 200V, I had obtained full CW output on all but 10 meters and was starting to work on the audio problems,  where I now had good carrier suppression but considerable noise and very weak audio.
 
First, at Nick Tusa's suggestion I used a lot of deoxit on the tube sockets as there was lots of corrosion as I had noticed elsewhere on the rig during the RF stages debug. Then I started following thru the audio stages, tracing thru a 1000cps injected signal at the mic connection. Found good audio amplification and little noise until I got to checking V7 the audio phase inverter. Found a drastic drop in audio and huge amounts of noise injected. Started a resistance check and found a suspicious resistance reading on pin 1 of V7, a very low reading to ground, a few hundred ohms. A visual inspection showed the V7 tube socket ground lug, which was mounted along side pin 1 of V7, was actually touching pin 1 and a large amount of carbon had built up between the two points, apparently due to arcing over time at that point, and resulting in the low resistance reading rather than a complete short. Also, I'm guessing that the low resistance short caused
 excessive current flow over a long period of time thru R153 in that circuit, a 1% precision 7k resistor, because that resistor was now reading 48k. I replaced the original resistor and bent the ground lug down so it no longer came close to pin 1. Finished the resistance and visual checks and fired the CE-200V back up. Wow! What an improvement!  
 
I now had a decent 1000cps waveform output on the external scope, although with some ripple, and the trapezoid waveform on the 200V actually looked good. I performed the suppression steps from the manual and was able to pretty much eliminate the ripple.
 
With evrything looking good on the scopes, I gave a listen to the signal on my receiver and it sounded really good, a nice LSB signal on 75 meters. Switched to USB and gave a listen and....oops, it's still an LSB signal!. So I have something still not adjusted right, doesn't matter whether the 200V is in LSB or USB mode, I get a LSB signal. So still have to look further into that, but at least LSB sounds good, although I haven't actually gotten the rig on the air to make a contact yet.
 
Oh, also checked AM and that sounded good as well, showing about 25 watts output.
 
Won't get back to the rig for at least another week (my next weekend) but at least some more significant progress has been made. Here are a few pictures of the rig in operation:
 
http://www.w2ec.com/CE200V-LSB-1000cps.jpg
 
http://www.w2ec.com/CE200V-CW.jpg