[Drake] T-4X info

[Garey Barrell]

Larry -

Those two controls are VOX Gain and ANTI-VOX, front to back.

Start with the VOX full CW and the ANTI-VOX full CCW.  Bring up the GAIN 
control on the front panel until the plate current kicks up to about 150 
mA.  Then turn the VOX control CCW for the drop-out time you prefer 
between phrases, or ...   There is no delay control on the T-4X, delay 
being adjusted with the VOX Gain.

If you can't get what you want in the way of delay, you can change the 
value of R95.  R95 is the 4.7M (original) across the diode on the VOX 
board near C145, the 0.1 uF, 200V film capacitor.  The VOX tube is the 6EV7.

There is a small circuit in the transmitter that sends a pulse to the 
relay tube to pull it in FAST to prevent clipping of the first dot or 
syllable.  The relay is then held in by the sidetone oscillator tone as 
long as the key is down.  Most likely proper adjustment will solve your 
problem.  If not, check to see if the sidetone is present.   Sidetone is 
generated by switching the Mic Amp (12AX7) to a phase shift oscillator.

If no luck, let us know!

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>



telegrapher at att.net wrote:
> I recently came to be the owner of a T-4X.  Really nice and looks like the finals are good also.  No documentation.  I have the CD which covers the -C- Line but nothing in there that i swa says anything about the T-4X or B line.
>
> There are two controls on the right side of the transmitter.  I don't remember just what they are but one of them affects the keying of the transmitter.  VOX gain or something.  What happens is that when i depress the key, all i get is just a slight kick of plate current.  I'm suspecting that one of those two controls needs to be adjusted, but which one?
>
> Idle Ip is good and it loads up to full output.  Can't ask for better than that except to fix the keying.  Anyone with a manual for the T-4X or T-4XB as i think they are pretty similar.  And, what is the tube that works in that circuit.  Seems it was an odd number type?
>
> Larry
> W0OGH
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