[Amps] Problem with Emtron amp.

[la0cx at tutanota.com]

Hieveryone!


MyEmtron DX-1b with QSK-option (vacuum-relay), bought new in 2002, hasbeen working flawlessly with the original GU74b until some weeks ago.Never used with more than 700w out.


Todayssituation: When using the amp intensly, as within a contest, aftersome minutes, the protection system cuts off for some seconds, as forexample in case of hight SWR. However, this cut-off occursindependently of driving transceiver, power, antenna, SWR andtemperature. The LED-indicators for IG2 start quickly to rise, jumpover to «overdrive» and cut-off happens. After 2 sec. amp is readyagain, everything seems to be normal, but the symptoms repeatthemselves.


Ihave adjusted tx-delay in trcv with bk, semi-bk, full-bk andtransmit-receive button, keying by MOS or reed relay; no difference.


HVshows normal value at the meter: 2.6 kV


Isuspected the tube, so 2 weeks ago the original tube has beenreplaced with a (formatted) spare one, no difference. IG-voltage isexactly as required 356 V.


Trcvris a IC7610. It drives other amps (Expert 1K-FA, AL-572) withoutproblems.


Iwould be grateful for any hints.


73sfrom Norway


Uli,LA0CX


-- 
 Sikkert sent med Tutanota. Krev din kryptert postkassen i dag! 
 https://tutanota.com