Re: [Amps] Alpha 87A troubles with fault 17

[Rob & Terri Sherwood <rob@sherweng.com>]

I have a manual tune version of the amp, an Alpha 89, along with an 
Alpha 99.   See Walt, W0CP's web site on a fix for the 781 ALC spike 
problem. (W0CP.com)
While the spike is there with the Icom, I have not had nearly as much of 
a problem like you have with faults.  My ALC spike on CW, at worst is as 
follows:
Set the amp for steady state out put of 1 kW, and the spike can be as 
high as 1.5 kW.  My IC-706MkIIG has a modestly worse spike than the 781 
(before the mod).  With all the faults you have listed, I don't think 
you amp is working properly. 

Is there a possibility your have some kind of an arc problem on your 
transmission line?  At one of my QTHs I have a 40 meter extended double 
zepp fed with a Johnson KW Matchbox.  At one point on the transmission 
line the open wire feeders got squeezed  too close together. When I was 
tuning up with a carrier, as the output approached 1.5 kW the reflected 
power would go from about 20 watts to full scale and the amp would fault 
on excessive reflected power.  After inspecting the feedline the next 
day during daylight, I found that the feedline had been arcing at one 
point.  If you have a coax system, and a balun on a beam, for instance, 
it is possible the balun could be flashing over.  I had this difficulty 
with a Hy-Gain BN-86 once on a Hy-Gain 402BA.

73, Rob Sherwood, NC0B 


Andy Forsberg wrote:

> Hi All,
>
> I have a TS 950 and TS 2000 driving a New Alpha 87A. I am continually
> getting fault code 17 in SSB while talking which puts the amp into standby
> mode. The amp is tuned properly either using default, manual, or AlphaMax.
> Nothing seems to help.  Alpha factory will not return my e-mails so I have
> know idea how to get these radios to drive the Alpha.  When I took the amp
> out of the box at turn on I got a hard fault 24 and the amp would not come
> on line. After two power ups I finally got a green board. The first time I
> applied 20 watts drive power it faulted. That cleared I was finally able to
> get the amp to full power and sic.... operational. The fault code 17
> (extreme miss-match) started right away and have not stopped. I can not get
> through a transmission without a fault 17 occurring.
>
> I understand that Icomm 781's had this problem also? Are these ALC
> overshoots? Can they be prevented? Is this a problem with Alpha or Kenwood?
> Either way the amp is useless as long as it keeps faulting.
>
> Thanks for any help the group can offer,
>
> 73 Andy WW7A
>
> Latitude  N  47.35 degs
> Longitude W 122.95 degs
>
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