[Amps] PIN diode mods

[Peter Voelpel]

Pin diode modifications are useless if there is no circuit redesign to raise
the diode current to the correct value for the IMD improvement, the HP PIN
diodes Ulrich Rohde used in his articles need much more then standard
current.
If the "on" current is not raised the insertion loss improves IMD as any
attenuator does.

73
Peter


-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Jan Erik Holm
Sent: Mittwoch, 26. Juli 2006 12:48
Cc: amps at contesting.com
Subject: Re: [Amps] PIN diode mods

Then FT-1000D is a low end radio!
2nd order IMD improves over 20 dB when doing
PIN diode mod.
By the same time IMDDR3 2 kHz spaceing improves
approx 15 dB.
Voodoo....yeah right!

73 SM2EKM
---------------------------

Craig wrote:
> Most of the early PIN diode mods came from the information and articles 
> by Ulrich Rohde  N1UL.
> 
> The PIN diode mods were mostly for 2nd order  IMD  problems. There were 
> claims for  some minor improvements in blocking and 3rd order dynamic 
> range. However i seem recall most of the mods applied to low end radios 
> like the TS450 and TS50 which suffered  badly from  2nd  order IMD  in 
> places like Europe. I also seem to recall  that Signal One started 
> promoting the supposed advantages of the HP PIN diodes in the Mil 
> Packaged IC-781.
> 
>  Maybe  Ulrich with his well respected HF credentials and his vast 
> experience with collocated HF transmitters and receivers in military 
> markets became  the main   focus   for all his  measured  improvements.  
> The data measured  with very  wide spaced high 3rd order intercept 
> points may be valid using  better PIN diodes in  such a severe RF 
> environments. Only he could answer these questions.
> 
> 
> Craig
> VK3HE
>

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