I should stipulate in my FD story that we most certainly *could* hear
transmitted IMD and transmitted phase noise from the phone stations and a
digital station, which limited useful close-in receive capability. But that
stuff has a very different characteristic than does IMD generated within the
receiver.
I also have a TS-930S (bought new in 1982) in which I have installed the Inrad
6 kHz roofing filter (40 MHz 1st IF). Prior to this, the receiver didn't do
well in FD environments (to put it mildly) but with the 6 kHz roofing filter
it, too, became nearly immune to receiver IMD from other stations on the same
band. When I took it to FD, other ops were surprised that I didn't have the
troubles they were having. Thus was the the old dog taught a new trick!
In many ways my TS-930S is more convenient to take to FD because it has a
built-in power supply. With the PIEXX board installed, it's also subject to
computer control and so suitable for computer logging. With the requisite power
supply mods, it has become a very nice FD/visiting contest radio with a bit
less transmitted IMD than the 12 VDC radios because it runs the driver and PA
at 28 VDC.
Kim N5OP
________________________________
From: Rick - DJ0IP / NJ0IP <Rick@DJ0IP.de>
To: 'Discussion of Ten-Tec Equipment' <tentec@contesting.com>
Sent: Friday, May 2, 2014 12:44 AM
Subject: Re: [TenTec] Wide roofing filter for the RX-366?
Outstanding Kim!
This is exactly what the world of Yaekencom users don't realize they're
missing.
They accept 'intra-transmitter' interference at multi-transmitter events as
a given.
(I think I just made up a word.)
The acid test is when operating 4U1VIC in Vienna.
I've run CQWW DX CW from there several times.
At that site, ALL antennas from all stations have to be located on top of
the roof of the main building. You are not allowed to string wires to other
places, other buildings, etc. Of course that building is about 400 ft. tall
which helps the signal a lot.
(picture:
http://en.wikipedia.org/wiki/United_Nations_Office_at_Vienna )
In this case, you can't obtain the kind of separation recommended by K3LR
and W3LPL in their course on antennas for multi-multi contesting, which they
teach at Contest University in Dayton.
I always took along a pair of Omni VI transceivers. Some of the others
brought their flavor of the day Yaekencom. Even without band filters (which
weren't commercially available then), my two Omni's did not disturb each
other when operating on separate bands unless they were on an exact harmonic
frequency. The Yaekencoms were useless. Their owners cried all the way
home. They were in disbelief!
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
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