Dave,

Again, anything I say should be confirmed.    My understanding is that 
units made after Jan 1 2014 had the mods done at the factory.  At least 
that's the story  going around.

You can find production date from the s/n.   First character will be a 
"B".  Kenwood went to a new s/n system a few years ago and "A" would 
stand for the first decade of this century and "B" for the second 
decade.   No 590's were made prior to 2010, so all should start with a "B".

Second character is a number that indicates  year of production: 0 = 
2010, 1 = 2011, etc., to 4 = 2014.

Third character is month of production: 1 = January through 9 = 
September, A = October, B = November, and C = December.

After that are some  zeros and last, some digits that indicate actual 
production that month.

So it is the first 3 characters that tell  when it was made.   Mine 
starts with B14, which means made in April 2011.  makes sense since I 
bought it new in June 2011.

Again, you should confirm all this junk and decide if you want to  go to 
the trouble of resolving a problem that may or may not be there, and may 
or may not apply to you.

73, Steve KW3A

On 7/2/2014 10:00 PM, David Weigel wrote:
> Hi, Steve:
> 	Thanks for the information and commentary on the alc mod for the TS
> 590.  I purchased my TS 590S on February 8th from H R O at the Orlando
> Hamcation, and the transceiver was sent to me from the H R O Delaware
> office, arriving at my home about February 15, 2014.  Without additional
> information, I do not know if my TS590S was manufactured in the latter part
> of 2013 or early 2014, just before my mid-February 2014 shipment.  How does
> one come to know when the rig was manufactured?  Is there some informational
> sticker or other telltale sign on the rig itself?  Or does one just need to
> contact the vendor to learn of when the rig came to the vendor, taking into
> account some time for transit from Japan? (or was it China or Indonesia?)
> 	I am hoping that the special Kenwood TS 590 and VGS-1 sales campaign
> from last November/December "exhausted" the supply of pre-alc mod TS 590s,
> so that any TS 590s sold in February 2014 then had the factory alc
> 	So, please let us know of the secret of identifying the date of
> manufacture of the TS 590.  	Thanks.    Dave Weigel (pronounced: why
> gull)   KD4JEZ     Naples, Florida
>
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Steve Forst
> Sent: Wednesday, July 02, 2014 2:10 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
>
>
>