Bob,

I saw your post on the 590 list.  Are you sure the fuse has failed? 
Have you tried a full reset?   Maybe  set to the wrong antenna, or drive 
function  enabled, or rx only antenna activated.    Maybe none of the 
above, but it's worth poking around a bit and doing a reset if need be. 
  Nothing else to lose.

73, Steve KW3A

On 7/2/2014 6:27 PM, Bob, K8LR wrote:
> 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
>
>
>