[1000mp] PIN Diode Mod for Mark V

Mon, 12 Apr 2004 18:18:31 +0200

Hi, 

The HSMP diodes are good and produce measurable performance improvement in
the high signal handling. Just be sure you pick the right set not only the
type. 

It is difficult to get PIN diodes which perform goo at the bottom of HF.
Phillips had some in the BAR 6x series but they are off the production nw. 

73,

Zoli HA1AG

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Mike Schatzberg
> Sent: Monday, April 12, 2004 14:45
> To: [email protected]
> Subject: Re: [1000mp] PIN Diode Mod for Mark V
> 
> 
> 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: <[email protected]>
> To: <[email protected]>
> 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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