[TenTec] RF Speech Processor "TX IMD"

[Rick - DJ0IP / NJ0IP]

It is very easy to test without a spectrum analyzer.
All you need is two transceivers, a good one (eg. any Omni, Orion, or
Eagle), and one of the cheaper ones.
Then you need two antennas with reasonable spacing (should not be directly
next to each other).

With both radios running on separate antennas:
  <> Tune the good radio to another band and make sure it is not on a direct
harmonic of the cheap one.
  <> On the cheap one, turn the power up to 100w, and the mic gain to
minimum
  <> Key the cheap radio and do not talk into the mic
  <> Monitor the S-meter on the good radio.  Expect to see S3 to S9,
regardless of what band or frequency the good one is on.

With good radios, ie a pair of OM-6+ driving 600w linears, I have operated
many times at 4U1VIC with the stations side by side, just 6 ft. apart, and
all antennas on top of the roof of the building.  The radios did not bother
each other, except for about a 10kHz window centered on exact harmonics.
And this was without band filters.

BTW, a bandfilter on the good transceiver (eg, ICE, Dunestar, etc.) won't
help against these cheap transceivers.  Their broadband noise is on all
frequencies and passes freely through the bandpass filters.  It would
probably help to put one on the cheap transmitter, to reduce the strength of
the transmitted noise, but better yet is to throw the rig out.

73
Rick, DJ0IP

-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Barry N1EU
Sent: Monday, June 17, 2013 8:07 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] RF Speech Processor "TX IMD"

On Mon, Jun 17, 2013 at 5:56 PM, Rick - DJ0IP / NJ0IP <Rick at dj0ip.de> wrote:

> I understand how most of you guys who have never experienced this may 
> be finding it difficult to believe.
> But once you've experienced it live, I guarantee you will jump on the 
> bandwagon with me.
>

I have experienced this in spades, especially from FT-1000 variants and
TS-930S.

73, Barry N1EU
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