From: rec-radio-amateur-moderated-request@panix.com (OZ9QV via rec.radio.amateur.moderated Admin)


OZ9QV : Amateur Radio, Propagation and Electronics

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Quick Test of Some Receivers for Monitoring.

Posted: 04 Jul 2022 02:56 PM PDT http://oz9qv.blogspot.com/2022/07/quick-test-of-some-receivers-for.html


Over the week end I found some older scanner receivers etc that I want to
use for propagation monitoring and general (local) traffic monitoring.
Because I like to have the monitoring running for hours every day, and
using solar power, I want to limit the power consumption.
Monitoring FM channels:
I have a 10m FM transceiver that I intend to use for monitoring 10m FM on 29.600. Draws 160mA on receive, which is acceptable, though not ideal. Current consumption is still about 160mA, but it is better than using the IC-703. For 10m FM it is also possible to use a Bearcat UBC92XLT handheld scanner running 6V with 70mA current consumption. A voltage regulator reducing the 13V to 6V will be necessary for this (easily built).
For 6m FM, monitoring frequencies in the 51-52MHz segment I can use my
older Yaesu VX-5.
The best results of those came with 2 handheld scanner receivers, Bearcat UBC65XLT. These are 10 channel units capable of running in the 4m, 2m and 70cm bands. They draw 5mA when off, and 50mA when receiving.
I think that one of those should scan the 4m FM segment - 70.300 - 70-500 -
9 channels, and 69.900. the frequency pair 69.900/70.500 is allowed in Denmark for use with repeaters - yes 600kHz spacing, just like the 2m repeaters.
The alternative would be using a (Wouxun?) handheld for this purpose, if I can find out how to program its memories.
The second one can be used for 2m, and the 143.625 MHz, all in 25kHz
spacing system. 143.625 has been used by the space stations Mir and ISS for communication with the ground stations in Russia.
For 2m FM I could also use my older Kenwood handheld TRX, or a Baofeng as monitor, again if I can figure out how to program the beast. Since I have
no intention of transmitting with those I have no problem using those
Chinese radios for monitoring.
For 70cm I could use the Baofeng's again.
Now, what to do for 23cm? I do have an old Kenwood TM741 triband radio, and that could be useful for FM monitoring on that band. I will have to test
the power consumption of this one, but it does have the advantage of being capable of running 3 bands simultaneously, with additional transmit capability. I can likely find a low power scanner capable of running 23cm.
We shall see.
I am well aware that some antennas will be necessary for all this (and
more) monitoring.
The advantage of receive-only antennas is that the preamplifier, if it is necessary, can be placed close to the antenna, so a low cost coax cable (cheap satellite cable) can be used.
The 10 - 6 - 4m, and 8m bands could be covered by a TFD antenna about 2.5m long, hanging in a tree in the garden. Essentially invisible.
For 2m, 70cm and 23cm a short tri-band vertical can be used, with a
wideband preamp, and stilll the low cost cable. Not invisible, but
relatively discreet. Yes I am aware of the possible overload of some receivers when transmitting, but that is, for now, an acceptable compromise. For reception on bands in between - such as air band and FM broadcast radio of both Western European and Russian stations, a wide band antenna, such as
a discone or a log-periodic antenna could be used with a wideband preamplifier.
The next level will be some monitoring using FT8 and beacon reception, and this requires more sophisticated reception systems capable of SSB. I have some ideas, but this will have to wait for another time.

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