[drakelist] TR-4 TX Hang-Up

[Byron Tatum]

Hello-
    I have an unusual problem perhaps someone could shed some light on:
        I have a TR-4 in 29K serial range that functions normally except it 
will not go back into receive, until after approx 30 second delay, after the 
mic button is released or the function switch turned back to "SSB". This 
condition worsens (longer delay) the more you frequently you transmit. The 
sidetone disappears but T-R relay will not release.
    I have tried different known-good 6EV7 tubes, have replaced a lot of the 
coupling / bypass caps in T-R circuits, did resistance / voltage checks, 
adjusted the VOX / VOX delay controls, tried other tubes in T-R circuit, etc. 
to no avail.
    What is real curious about this is that while waiting for it to go back 
into receive and T-R relay is engaged, IF YOU PULL THE 6EV7 FROM ITS SOCKET THE 
T-R RELAY STILL DOES NOT RELEASE. I suspect the issue is with the lead that 
goes from T-R relay coil to pin #1 on 6EV7 (somehow allowing enough leakage  to 
ground?) or could it be the T-R relay coil itself?? I made sure socket / pins 
and all are clean on 6EV7.
    Any help appreciated, thanks.
                    Perplexed,
                                Byron WA5THJ.