[1000mp] IP3 on Rob Sherwood's site

[k5uj at mc.net]

Thanks Bill,

73
rob/k5uj

-----Original Message-----
From: w9nhq at comcast.net
To: k5uj at mc.net
Sent: Oct 14, 2004 10:56 AM 
Subject: RE: [1000mp] IP3 on Rob Sherwood's site

I respectfully suggest that anyone who is really interested in the subject
of PIN Diodes, as they relate to receiver performance, read Dr. Ulrich
Rohde's articles on receiver design that appeared in 3 different issues of
QST back in 1994.

According to Dr. Rohde, PIN diodes DO make a difference, but primarily in
the area of improved 2nd order IMD.  This can happen when 2 nearby broadcast
stations cause a spurious signal to appear on 160 meters, or (in my case)
when strong commercial shortwave signals, received with a large log periodic
antenna, result in unwanted images on the higher bands.

Yaesu already included PIN diodes in those areas where they can make a
difference.  This was discussed in the last paragraph on page 69 of the
Product Review in April, 1996 QST.  It takes all of about 10 seconds of
listening with a 10-30 MHz LP at 75 feet to see the superiority of the MP's
front end to that of lesser rigs.

73,

Bill, W9NHQ


----- Original Message ----- 
From: <k5uj at mc.net>
To: <1000mp at mailman.qth.net>
Sent: Thursday, October 14, 2004 9:12 AM
Subject: RE: [1000mp] IP3 on Rob Sherwood's site


> Okay, let's see.  So now we are out of the laboratory and into the real
world (just checking).  I was given to understand that the noticability of
the mod's difference was due to the greater reduction in noise from man-made
sources and thunderstorm static on the higher bands, especially 10 m.,
compared to < 14 MHz, in SSB operating.  BTW Bill, I'm sure you know that it
doesn't take much of an antenna to get some very strong signals on 10 when
it is open.  You should try one of those 10 meter contests sometime.
>
> Cordially,
>
> Rob/K5UJ
>
>
>
>
>
> K5UJ wrote:
>  >my understanding of the mod is that it affects performance
> (if it does anything at all) above 20 m.
>
>          More likely the other way around unless you are using very
> high gain antennas on the high bands.  The reason being that
> extremely strong (S9+30) interfering signals on the low bands are
> much more common than on the higher bands.
>
>                                          73,  Bill  W4ZV
>
>
>
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