Tram D201 tvi tune c711

[klj2497]

Im trying to track down the low output problem on am/lsb I noticed the c711 was set so it looked like a circle instead of a slice of pie like the other radios from the inside. i checked c711 and from L700 to the 3 pin on the final tube i get 3.7 ohms. The other tram measured 37.6ohms. from L700 to pin 3. i do not know what to make of it.

 

[nomadradio]

Three ohms and change looks about right. The one that reads 37.6 has a loose wire on the parasitic choke L703.

What kind of tube are you using for the final? We have had problems with low output using a particular kind of russian 6L6. Has totally straight sides from the plastic base to the top. We have seen this one with a half-dozen different brands painted onto it. A tube with too much capacitance from the plate to the screen grid will cause C711 to appear to peak, when you set it for minimum capacitance, the plates fully apart. It's not really a peak, the control ran out of adjustment range before reaching a proper resonant-tuned peak.

Sometimes soldering a short across the outer turn and the turn next to it on L700 will move the peak setting for C711 back into range between the extremes of max and minimum capacitance.

Most any other 6L6GC tube tends to work okay as the final in a 23-channel D201.

C711 has to peak with the plates at least partially engaged to get full output.

73

 

[klj2497]

You are right its a russian tube. I put another tube in and c711 adjusted without running out.You are amazing nomadradio.

 

[nomadradio]

Rock on!

Good to hear it was that simple. Sometimes a little folklore goes a long way.

73