[R-390] MF/LF Reception

[millerke6f at aol.com]

Hi to al


While this is a bit off the usual list of hardware, 


Tis a good time to look at the Frequency Selective Voltmeters out there gathering dust.  Since most long lines communications have dumped FDM multiplex, the SVMs are available pretty cheap.  Granted they lack an AGC/AVC scheme, but most are quite stable and can dig down well below the ambient noise level as well.  Ones to look for at the HP 312 series which are good to well under -110dbm with selective BW from a few hundred Hz to include SSB BWs. HP 310 ok but not as good as the 312  Others are RYCOM,  Siemens, Wadel Golterman {Spelling) Philco, and a host of others that don't come to mind.  


73
Bob, KE6F



-----Original Message-----
From: Don Reaves <donreaves at gmail.com>
To: R-390 List <r-390 at mailman.qth.net>
Sent: Mon, Sep 18, 2017 3:42 pm
Subject: [R-390] MF/LF Reception

The ARRL has announced the official opening of the two new US ham bands,
630 and 2200 meters.  First day of operation will be Oct 15 of this year.
I expect considerable activity on the 630 meter band, which is officialy
from 472 - 479 kilocycles.  Currently there are dozens of experimental
licenses issued by the FCC in that range, and these are active stations.
But with the band becoming available to all hams of General Class or
better, there should be a flurry of initial activity, including budding
interest in firing up old military LF transmitters for CW operation.
There will be digital modes, WSPR beacons, regular QSOs, and who knows what
else.  Power is limited to 5 watts Effective Radiated Power, but that is
enough to work the world when propagation is favorable.

There are more challenges to getting active on 135.7 - 137.8 kilocycles,
due to less equipment availability and physical limitations to erecting
decent transmitting antennas for 136 Khz operation.
An efficient end fed resonant quarter wave antenna will be over 1600 feet
long.

Nevertheless, these two new bands add to the listening targets for our idle
receivers.  The easiest way to get your R-390 on these new frequencies is
add a LF converter ahead of the receiver.  Another easy way is to adopt the
use of an external LF tuning network ahead of the receiver's first mixer
stage, via a built in test point.  Breck, K4CHE, has an excellent treatise
as I have mentioned before.  He has updated the technique with some great
documentation.

http://k4che.com/R390LF/R390LFVar.htm

For my R-390A and an Icom transceiver that falls down on receive below the
BCB, I use an old but serviceable Palomar Engineers VLF-A converter (the
red one with an external 9V battery) which up converts the 10 to 500 KC
range to 3.51 to 4.0 MC.

Having an R-389 lying about now seems prescient.

Don
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