[Drake] T-4XB gain drops as warms up Why?

[Garey Barrell]

Jim -

I can't say I've ever run into that one before......

Does the  _idle_  plate current change, or just loaded plate current and 
output power?

Just a quick guess, check R26 for value and condition.

73, Garey - K4OAH
Glen Allen, VA

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



k9jmlinux at gmail.com wrote:
> I have an R-4B/T-4XB combo. The gain varies during the first half hour of  
> operation. For example, on CW, to make full power when it is cold, the gain  
> knob will need to be at about 10 o'clock. As it warms up, the power drops,  
> eventually to about half power. Re-peaking the RF TUNE or the final tuning  
> indicates that neither has changed. To get to full power again requires  
> increasing the "GAIN" to perhaps the one o'clock position.
>
> I have check and swapped out tubes. No luck. I haven't dung in to find out  
> what stage is changing. The time constant is long enough that it will not  
> be a quick debug. Anyone experienced this and have any suggestions.
>
> Appreciated
> 73 de
> Jim K9JM
>
>