[ICOM] Problem with IC-781 and rising power

[Adam Farson]

Hi Guillermo,

The IC-781 group may also be able to assist you.

http://groups.yahoo.com/group/IcomIC781/

Cheers for now, 73,
Adam VA7OJ/AB4OJ
 

-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of GGLL
Sent: 6-Sep-09 11:08
To: Icom
Subject: [ICOM] Problem with IC-781 and rising power

	Hello, I'm trying to fix a nice 781 with a strange problem. In any
mode, at any band, after I push PTT for transmit it tooks three to four
seconds to reach full power (150 watts and whatever power output I set with
R49). Just the 781 alone, no linear amplifier.
	I've traced that at soon I press PTT, the bias for the RF TX
amplifiers
(Q32 and Q39) raise from -1.6V upto 3.5V in the above stated time instead of
being instantaneous at 3.5V. Q30 seems to switch properly also.
	I've replaced Q35 which had a small leak, and the ALC system has
already K1VF ALC mods for the power spike.

Any hint, advice, is indeed welcome.

Regards
Guillermo - LU8EYW.