[1000mp] PIN Diode Mod for Mark V

[Mike Schatzberg]

Hi Dale and Hans:

I am trying to learn more about this change, and have received unconfirmed
information that the component changes involve the addition of  HP 5082-3081
diodes.  The total number of component changes may be in the range of 50,
and the time to make the changes, 4 to 5 hours.  This is pretty major, and
to make things more difficult, I'm not sure that radios which have received
this mod, have had new schematics provided with the changes.  I'll let you
know more when I learn something new.

My QTH is on a  hill top, and I have just spent about 6 months removing all
the QRN produced by the high voltage insulators bringing me power up the
hill through my farm.  The power line is about a half mile long, now is
totally clean, and I have an S zero to S 1 noise level finally.  I want to
improve the receiver for QRP operations, and be able to pull all the weak
signals out of the background noise, and copy these S zero to S one signals
far more easily.  With the current Sun Spot cycle point, there are many very
low level signals now.  I am currently installing a second tower, with
monoband antennas to further help with these conditions.  The receiver I am
told is so quiet after the change, that you would think it is indeed a
different radio.  Ten Db improvement is tremendous.  I have already
optimized the Mark V settings to provide the best signal to noise ratio, but
I want the receiver even quieter.

Regards,

Mike Schatzberg
WB2AJI

----- Original Message ----- 
From: <dalej2@mac.com>
To: <1000mp@mailman.qth.net>
Sent: Monday, April 12, 2004 4:51 AM
Subject: Re: [1000mp] PIN Diode Mod for Mark V


> I just checked my MKV schematic of the  receiver RF unit input bandpass
> filter switching diodes and they are 1SV271 which a quick search found
> they are made by Toshiba and called Silicon Epitaxial Pin type diodes.
> So I also am curious as to where else the MKv might be lacking  pin
> diodes.
>
> 73
>
> Dale, K9VUJ
>
>
> On Apr 11, 2004, at 22:09, Mike Schatzberg wrote:
>
> > Hello All:
> >
> > Can anyone provide details about the Yaesu PIN diode mod for the Mark
> > V which reduces receiver noise by 10 Db?  This change is apparently
> > not quite so simple, and may involve more than just a few component
> > changes.
> >
> > Thanks for your collective inputs.
> >
> > 73,
> >
> > Mike Schatzberg
> > WB2AJI
> >
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