[Kenwood] Pin Diodes for TS-930

[WR2E]

I was the one who initially recommended the 519 to Jim as a possible
replacement for the 2588 pin diode.  I have used this diode to repair
a number of 440's with bad diodes.  These radios continue to work well,
and show no OBVIOUS signs of degraded performance.  Perhaps doing IMD
tests you might see some difference, but I doubt it.

With so many of these diodes being replaced in the KW radios, it occurs
to me that the ORIGINAL part was a piece of CRAP.  Probably produced in
some "dirty" plant somewhere in Japan.  OR, under rated for their use.

In most cases, the ECG parts actually have BETTER specs than the parts
that they are replacing.  This is BECAUSE they have to fit a wider range
of parts... but Eric is correct that in some cases they don't work.  One
case in point is horizontal output transistors in television sets... I've
had trouble with those.

Jim, and others... I've got some "feelers" out for the original 2588 diodes.
I'll know next week whether I'll  be able to obtain these at a reasonable
price.  If I can get them, I will make them available to other hams in need.
My recommendation would be to NOT use them, given their failure rate.

The NTE 177 is another possible candidate for replacing the 2588 (or the
1SS91S which is also used in some radios).

The  MPN3700  is a PIN DIODE in a TO92 package ... it meets the spec
requirements electrically, it is of course a bit larger than the axial
leaded part, but in most cases will probably fit in it's place.  It is
cheap ( appx 50 cents ), and available (digikey, jameco, newark,
{10 for $3.00 at www.partsandkits.com}).  I'll be trying some of these
in one of my 440's and will report the results.

MPN3404 is also a PIN diode in a TO-92 but lower voltage/current.

SOME of the generic 1N4007 diodes are also PIN structure, believe it or
not, but as far as I know, there is no way of knowing which is which 
without testing them.

When the ECG devices were still being sold, (before NTE "squashed" them),
they sold an  ECG 553  which WAS labeled as a PIN diode.  I used these
exclusively until they were no longer available.  I don't know if the 
NTE 553 is the same part though.

PIN diodes are widely available in SMT packages these days.  I'm working
on designing a "carrier" that would allow their use in place of the old
parts... more on this later.

If anyone has a DATA SHEET on the original 1S2588 that Kenwood used, I
would love to have a copy of it.

Merry Christmas! (or Happy Holiday OYC)
73 de Jeff / WR2E

> ------------------------------
> 
> Message: 6
> Date: Fri, 24 Dec 2004 12:43:37 -0500
> From: "Jim Dicso" <dicso123 at hotmail.com>
> Subject: Re: [Kenwood] Pin Diodes for TS-930.
> 
> Eric,
> 
> Thanks for your sound advice.
> 
> Several Google searches have yielded part #'s by HP, Microsemi and others
> and some small quantity sources.
> 
> I'm sure you've seen the 'cheap' gene behaviour,  no PIN diodes in stock but
> thousands of  switching diodes  in stock ....
> I have to fight the urge to use the switching diodes andf go with PIN
> diodes.
> 
> Regards, Jim K2SZ
>