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<a class="moz-txt-link-abbreviated" href="mailto:tvsjr@sprynet.com">tvsjr@sprynet.com</a> wrote:
<blockquote cite="midE1ECUR4-00049F-6K@smtpauth05.mail.atl.earthlink.net" type="cite">
<blockquote type="cite">
<pre wrap="">You won't "fry them". You will only overload and temporarily block the
receiver of one radio while the other one is transmitting. In the case
of the APRS radio transmitting, that means you will get a one second or
so hole punched in your 2M voice RX whenever the APRS radio beacons.
[ I have THREE antennas attached to radios capable of transmitting on 2M
and 450 (Kenwood TM-742, TM-D700 and Yaesu FT-100) within 3 feet of each
other on the roof of a Passat wagon with no problems other than receiver
blocking. ]
</pre>
</blockquote>
<pre wrap=""><!---->
Don't be so sure. I think I'm OK to comment here... I've got 15 mounts on
the roof of my Expedition, and just installed 20 today on the roof of my new
truck (actually, in the topper). I have fried an amateur radio (D700) and
the preamp in an Optoelectronics Scout connected to an external antenna with
a high-power (110-watt) Motorola VHF Astro Spectra.
</pre>
</blockquote>
20 antennas on one vehicle roof? How close together were they? Just
inches? You might as well as had the radio transmission lines
connected together with coax T connectors for all the isolation you
had! <br>
<br>
With minimum separation of a couple of feet or more, I've never had
any problems. <br>
<br>
<blockquote cite="midE1ECUR4-00049F-6K@smtpauth05.mail.atl.earthlink.net" type="cite">
<pre wrap="">
No reason to spend thousands and thousands of dollars. Since the analog
Spectra has been EOLed, you can pick them up sub-$200 (Astro P25 radios are
quite a bit higher, but that's another story.) The Spectra is arguably the
best commercial radio ever made.
</pre>
</blockquote>
<br>
I would agree. I've used Spectras as a front-end for my radio coverage
mapping system for years. I tap out the 109 Mhz first IF and feed them
into my IFR-1500 service monitor. The Specta working as a preselector
and pre-amp allows the IFR analyzer to see down to -120 dBm or so
while not getting overloaded by out-of-band RF. (Like most service
monitors, the IFR receiver front end consists of a double-balanced
mixer with no selectivity in front of it. For listening to a radio's
TX hardwired into it via coax, it's no problem. Off-air monitoring
with an external antenna causes the IFR RX to overload on mixes of
everything from "DC to light") <br>
For passive selectivity, I have a bunch of single cavities for
various bands (VHF, UHF, 800/900) that I peak up on the test freq with
the IFR's tracking generator; then use as preselectors for the RX.
When I need serious sensitivity as well, I break out the Spectras. <br>
<br>
<br>
<blockquote cite="midE1ECUR4-00049F-6K@smtpauth05.mail.atl.earthlink.net" type="cite">
<pre wrap=""></pre>
<blockquote type="cite">
<pre wrap="">o The only TOTAL solution is to conduct voice operations on another
band.
High-power commercial radios will often block hammy rigs across multiple
bands.
</pre>
</blockquote>
</blockquote>
Here I meant using alternate bands on the same dual band ham
transceiver (i.e. UHF) so that the usual simple hipass/lopass diplexer
could provide the isolation. <br>
<br>
<br>
<br>
<br>
<br>
Stephen H. Smith wa8lmf (at) aol.com <br>
EchoLink Node: 14400 [Think bottom of the 2M band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.com">http://wa8lmf.com</a><br>
<br>
"APRS 101" Explanation of APRS Path Selection & Digipeating <br>
<a class="moz-txt-link-freetext" href="http://webs.lanset.com/wa8lmf/DigiPaths">http://webs.lanset.com/wa8lmf/DigiPaths</a> <br>
<br>
Updated APRS Symbol Chart <br>
<a class="moz-txt-link-freetext" href="http://webs.lanset.com/wa8lmf/miscinfo/APRS_Symbol_Chart.pdf">http://webs.lanset.com/wa8lmf/miscinfo/APRS_Symbol_Chart.pdf</a> <br>
<br>
New/Updated "Rev G" APRS <a class="moz-txt-link-freetext" href="http://webs.lanset.com/wa8lmf/aprs">http://webs.lanset.com/wa8lmf/aprs</a><br>
Symbols Set for UI-View, <br>
UIpoint and APRSplus:<br>
<br>
<br>
<br>
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