[Amps] Alpha -91b Problem

[Vic Rosenthal]

Brass Pounder wrote:

> A friend of mine (W6AAN)  reported a problem with his Alpha-91b (2XGU-74B, 
> made in Bulgaria): when attempting to send CW at speed more than 5 WPM at 
> 1500W output,  the protection kicks on. Nothing similar happens at output 
> power less or about 700 W. The same RIG (TS870S) works just fine with a 
> different amplifier. 

Put a scope on the input and look for overshoot on the leading edges of the 
dits.  I am not sure if the 870 is one of the bad actors in this respect.  If it 
is like the TS850 with a separate power output and carrier level control, try 
cutting back the carrier control until output just starts to drop off.  This 
will reduce the possibility of overshoot.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco