[1000mp] S-Meter Adjust Worked and what about the "PIN Diode Mod?"

[WD8ARZ]

----- Original Message ----- 
From: "RCARIELLO" <RCARIELLO at si.rr.com>
To: "WD8ARZ" <wd8arz at ix.netcom.com>
Sent: Sunday, October 10, 2004 11:10 AM
Subject: Another Yaesu Question
>

> Bill,
> Just adjusted my S-Meter on my Yaesu ft-1000mp.
> The operation was very simple.
> Thanks again for your help.
>
> I am wondering if you have ever heard of this modification
> "pin-diode change front and back" for the Yaesu FT-1000mp.
> A couple of friends of mine had this done by Yaesu. I am
> considering doing it myself. Being inside the radio for the most
> part it looks very simple to remove a circuit board to work on.
>
> If I can get the information I'll consider changing the diodes.
> I understand this modification lowers the noise floor of the rig.
>
> Thanks for your help.
> Hoping you will be able to help again.
>
> Rich AA2MF
---------------------
Ok Rich, From Bill - WD8ARZ

Glad to hear that the S meter adjustment worked out so well for you, and so 
quick too .... hi hi

On the Pin Diode Mod. Which one??

For the front end diode mod, I am missing the specific information as far as 
what radios it affected and what serial number break point for those that 
need it and those that don't. I suspect this is very different than the 
topic of changing out the switching diodes that is mentioned here from time 
to time.

The 'other' Pin diode switching topic I have heard about, I was going to 
pursue myself. I have that info captured some where on my hard drive, but I 
have at this time canceled any of my intentions to do that project. I will 
be glad to locate it and make it available if it has not already been found 
on the internet somewhere. Would love to hear from those that made before 
and after equipment measurements doing this mod! Hi Hi

It had seemed to me that if this project was so good, it was a excellent kit 
mod for Inrad to do. So I sent him a email asking about that, and here is 
his response:

----- Original Message -----
From: "WD8ARZ" <wd8arz at ix.netcom.com>
To: <INRAD at rosenet.net>
Sent: Sunday, April 18, 2004 4:32 PM
Subject: New Kit Idea?? HP 5082-3081 diodes Upgrade

 I think this would be the next great kit idea from you for the
 MP/MkV/Field series.

 How do you feel about this? I would be willing to do some a
 early mod on this and report back to you on the effort.

 73 from Bill - WD8ARZ

----- Original Message ----- 
From: "International Radio" <inrad at rosenet.net>
To: "WD8ARZ" <wd8arz at ix.netcom.com>
Sent: Monday, April 19, 2004 2:05 PM
Subject: Re: New Kit Idea?? HP 5082-3081 diodes Upgrade


Bill,

First of all, this pin diode mod thing is a myth.  Pin diodes are not as
good a switch as regular switching diodes.   I think the input diodes are
already pin diodes (could be wrong without looking).
Once past the input filters there is no need to use pins.  Most people that
have done this mod report lower noise.  The reason for it however, is due to
the extra losses created by the higher resistance pin diodes.  The net
effect is a higher noise floor and poorer sensitivity.  People without a
good generator cannot tell this, of course.

Secondly, the attached message stating 10 dB reduction in internal noise
makes no sense as most of the noise is due to the 455 kHz IF and the pin
diodes are far away from that.  Unless of course his noise floor went up by
10 dB.  If everything worked as well as the theory suggests, there would be
NO change in internal noise.  The third order dynamic range would be
increased by 3 to 6 dB (not noticeable to the operator) and the second order
dynamic range could be improved by a substantial amount.  Second order means
two signals that add or subtract to give the tuned frequency.  i.e.  8 + 6 =
14, etc.  Most people don't have a problem with second order for several
reasons.  1. The 1000 MP is already good.  2.  The Mark V VRF preselector
eliminates the need as it makes the radios second order DR so high it can't
be measured without burning up the radio.  3.  Monoband antennas don't
respond to signals that far away from the tuned frequency.  And 4.
Contesters use external band pass filters which also eliminate the problem.

Thanks for the thought, however.  Watch our web site for an announcement of
a new roofing filter mod we are coming out with that will make a REAL
improvement in DR performance.

George
------------------------------

Having the ultimate trust in Inrad George's opinion, I canceled any further 
pursuit of this project.

However, maybe some of those in the previous dialog would like to share more 
in on some aspects of this?

Best to All Once Again, and I am off to long work hours again, so it will be 
some time before I can get back in here. Hope others pick up on this and 
contribute some excellent dialog as is so often the case for this wonderful 
group!

73 from Bill - WD8ARZ

> ----- Original Message -----
> From: "Brad Hedges" <bhedges at nc.rr.com>
> To: <yaesu at contesting.com>; <W7SV at sbcglobal.net>
> Sent: Sunday, April 11, 2004 8:19 PM
> Subject: [Yaesu] 1000MP MkV pin diodes
>
>
> Kirby, W7SV, said:
>
> My MK V has performed flawlessly for 1.5 yrs. Yaesu did the front
> end pin diode mod which reduced the internally generated noise by
> about 10 db!! Makes it sound like a whole different radio!! I just
> added the HP pins to my FT1000MP, and it made a big difference
> also!! Highly recommended!! HP 5082-3081 diodes
>
>73

> Kirby,
> Can you tell us more about this? I am somewhat familiar with
> InRad's noise blanker mod which cuts down IF noise - is this a
> related and/or same thing? Is there a web site talking about this?
> Did Yaesu do this for free as a factory recall kind of thing, or was
> it something you requested?
>
> Thanks in advance,
>
> A fellow MP (Field) owner and enjoyer,
> Brad
> K0BHC
> Sergeant First Class, Infantry
> 82d Airborne Division
----------------------------