Hi,
I have to send my TS590 back to Kenwood as a power failure here finally
blew that f-901 fuse.
I wasn't going to have the ALC mod done as I have never had trouble with
either my ALS600 or my ALS1300 amps while using the TS590. After reading
Steve's great explanation of the ALC mod, I'm going to have it done while
Kenwood East is replacing the fuse. I wonder how powerful the magnifying
glass has to be to work on that little surface mount fuse?
Bob, K8LR, [log in to unmask]
-----Original Message-----
From: Dr. Ronald E. Milliman
Sent: Wednesday, July 02, 2014 6:10 PM
To: [log in to unmask]
Subject: Re: Kenwood TS-590 ALC mod
Steve, thanks for the heads-up re the TS-590 mod. I purchased mine new last
November; so, evidently, if I operate my ALS-600 with it, I really should
have the mod installed.
Ron, K8HSY
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Steve Forst
Sent: Wednesday, July 02, 2014 1:10 PM
To: [log in to unmask]
Subject: Kenwood TS-590 ALC mod
Not sure if anyone else on the list has had this done, but figured I
would share my experience.
First, don't take anything I say as Gospel, confirm with another source.
The 590 has had a known issue of ALC/power spike and Kenwood is now
offering a free mod to fix. You need to send the radio to a Kenwood
service center at your expense, and Kenwood covers the mod and return
shipping.
If this spike exists on a particular radio, it could cause a solid state amp
(or some high end tube amps) to trip their protection circuit.
Many solid state amp owners have reported no problems and all works
well. others, like me, found the amp tripped with only modest drive.
in my case my THP 1.2kfx which should put out 750 watts pep, with a
drive between 75-90 watts, would trip off with much less. On 10
meters I was limited to about 35 watts drive, 40 watts on 15, and 50 or
so on 20 meters. Lower bands could handle 60 watts. More drive and
the amp would trip.
Sent mine out in June to the Virginia Beach service center and had it
back in 12 days. Have had it back for a week and have run it with the
ss amp and no problems. Played some in the Canada Day contest on both
15 and 20 meters running 70 watts drive and no problems. THP is out of
business now and this amp would be expensive to repair, so I will probably
limit drive to 65-70 watts and hopefully the extra headroom will give it a
longer life. I'll treat it like a 550 - 600 watt amp instead of 750.
So I was happy with the result. Your mileage may vary. The mod
consists of some hardware changes and some changes in the alignment
procedure. If your 590 was built starting in January 2014, the changes
were implemented at the factory. Anything built from 2010 - 2013 can
get the mod if you desire. Obviously most of these radios are long
out of warranty, but kenwood is treating this as a warranty repair.
Mine was built in April 2011 and purchased in June 2011.
Anyway, that's my long winded story.
73, Steve KW3A
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