[ICOM] IC-746PRO Spikes

[Adam Farson]

Hi Curly,

You can try terminating the IC-746Pro with a 50-ohm dummy load, and
observing the RF envelope on an oscilloscope. There should not be any large
RF spikes when keying up in SSB mode, or significant overshoot when keying
up in CW/RTTY/FM mode. If you see a spike of 100W or more, or a severe
overshoot, the radio's ALC circuit may be defective. 

I have been driving a Yaesu Quadra with various Icom exciters for over 7
years, and have never encountered an overdrive or RF spike problem. The
Quadra uses the same RF power devices (MRF150) as the ALS-600.

Do you have the ALC line connected between the ALS-600 and the 746Pro, and
have you calibrated the ALC as instructed in the ALS-600 manual?

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 K7HRW at adelphia.net
Sent: 07 January 2006 12:04
To: ICOM at mailman.qth.net
Cc: boatanchors at mailman.qth.net; forsale-swap at mailman.qth.net
Subject: [ICOM] IC-746PRO Spikes

Can anyone help on the above actually happening, and possible suggestions
for elimination. Have blown the four final amplifier transistors on the
ALS-600 Ameritron, twice. We are searching for an answer/solution.
73, Curly K7HRW/AFA6ES
----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net Icom Users
Net: Sundays, 1700Z, 14.316 MHz Icom FAQ: http://www.qsl.net/icom/



Scanned for viruses by Blue Coat
http://www.WinProxy.com/