[ICOM] IC-746PRO Spikes

[Curly Silva]

Hello Adam.......Tks for your response. No longer have a scope, don't have 
any room. May be able to accomplish the same type test with the PRO into my 
dummy load using the Bird 43 and the analyzer. Yes, I made sure the ALC was 
set according to the manual. Have been adherring to the operational 
parameters faithfully. And always working into a 1:1 SWR configuration. The 
Ameritron factory tech, suggested a low pass filter between the PRO and the 
amp. Others on the air didn't seem to think that would solve the problem. 
They seem to lean on a keying interface between the two. So that is the 
reason I sent out the "Help Wanted Msg". Tks again.
73, Curly, K7HRW
______________________________-
----- Original Message ----- 
From: "Adam Farson" <farson at shaw.ca>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Saturday, January 07, 2006 1:38 PM
Subject: RE: [ICOM] IC-746PRO Spikes


> 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
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