[Kenwood] TS-940S - How to identify Genuine Kenwood Modifications

[Kenneth G. Gordon]

On 21 Jun 2011 at 11:10, Dr. David Kirkby wrote:

> There is one for example of replacing the hard to get driver
> transistors with 12 V ones. My guess is the linearity would be poorer
> and it would be better to use 28 V transistors. The person describing
> the mod had not verified the performance of the transmitter with a
> spectrum analyser. That's what I'd consider dubious.

I would certainly agree.

> Most receiver mods seem to be based on S-meter readings, not with
> signal fed from signal generators and viewed on a spectrum analyser.

Again, IMHO, you are absolutely correct.

> In any case, there's a lower limit on sensitivity beyond which there
> seems no point in trying to achieve due to the atmospheric noise.

Yes. However, atmospheric noise levels vary greatly, even seasonally. 
I contend that the any noise contribution by a receiver should be at 
the absolute minimum at all times in order to take advantage of those 
times when atmospheric noise levels are "unusually" low.

One of my pet peeves is unnecessary receiver noise. Most mixers are 
horrible.

> A lot of people appeared to have made a lot of mods, but I'm not
> convinced many of them have been properly investigated.

Again, IMHO, you are absolutely correct. In my experience, MOST "ham 
mods" are not thorougly thought-out and, more often than not, make 
the equipment involved operate worse than stock.

> > Kenwood did not design their radios to be as you put it:
> > "Neater, easier to service, less confusing to someone trying to
> > service one like myself." Because Kenwood never expected or wanted them
> > to last so long. Most manufacturers in fact do not want products to
> > last.

I agree with this also. In fact, MOST radios were never designed to 
last so long. In fact, despite their often more robust construction, 
military radios are meant to be expendable...like ground troops.

> > For the LT1028 reduced phase noise modification and the PLL unlock
> > repair are found on read about it at:
> > http://homepages.ihug.co.nz/~jaking/TS-940_02.htm
> 
> I find that page, which I believe is yours, hard to follow.

I agree. I have studied that page, and others connected with it for 
some time, and am still confused by parts of it.

> The areas
> in gray are almost impossible to read. The links don't work either.

Correct. I have had the same trouble.

> I think I found it with Google
> 
> http://www.jking.kol.co.nz/TS-940_02_part2_1.htm
> 
> It would be good if you could provide a summary page of what you feel
> are worth doing on the TS-940S, and avoid discussing the things you
> don't feel are worth doing.

Agreed.

> The problem I have is the only major problem (PLL unlock) is
> intermittant. Those sorts of faults are hard to track down.

>From my nearly 40 years of trouble-shooting such problems, yes. I 
have sometimes told my "customers" (I worked at a University for 
almost 30 years), "When your intermittants become permanent, bring it 
to me. Otherwise, don't bother.".

BTW, Dr. Kirby, there is a forum devoted exclusively to the TS-940 
whereon you may find other helpful information.

Ken Gordon W7EKB