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© 2010 Arctic Diamonds - TF4M
One operating position is ready – position B which has the control unit for all antennas. Some work remains, dressing cables, installing computers and building brackets for Bandpass Filters etc.
During my Arctic Diamonds presentation on the CCF/OHDXF Ferry Cruise in January, – Tonno, ES5TV asked me whether I had any ”normal” antennas to compare my rhombics with.
My answer was a tongue-in-cheek reply to the effect that since I had unlimited space at my disposal, I wasn´t interested in limited space antennas.
A fellow Rhombic owner who indeed has such a comparison antenna sent me the following audio files which demonstrate the difference between the reception of ”normal ” antennas and Rhombics.
The first audio file is of TL0A an Amateur Radio Station located in the Central African Republic, recorded using a huge Log Periodic at 30 meters height.
Most Radio Amateurs would kill to have such an antenna ! 
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The second recording is made 3 minutes later, from the same location, but this time using a Rhombic antenna to receive TL0A.
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A visual comparison of the two files says more than a thousand words:
TL0A on LP antenna
TL0A received with a Rhombic
My Rhombic colleague commented as follows:
”… you will hear what a 30 meter high 6.5 dB gain antenna sounds like with a very wide radiation pattern. It is ideal to pick up all the noise and electrical storms in the equatorial noise zone.
The other recording is 3 minutes later, with a Rhombic with 20 dB gain, 10 meters high, low take off angle- and a beam width of just 10 degrees. It is not so much that the signal is that much stronger, it is that the noise is that much less. Note the ease with which it is possible to pick up and follow S1 stations that are very weak.
A Rhombic is not just about the gain, it is much more about the noise which you Dont Get…”
I rest my case.
I recently acquired a full instruction manual for the Harris RF-350K transceivers.
An ADDENDUM inside the front cover of the manual drew my attention and closer examination revealed instructions on how to program the transceiver for half-duplex operation.
Harris RF-350K
The inability to work stations in SPLIT mode during a pile up, has been one of the greatest drawbacks to using these fine radios on a regular basis, so it was with some excitement that I rushed to test one of my radios to see if this addendum applied to them – yes it works perfectly!
The procedure is as follows:
Programming is exactly as presently described in your manual for simplex operation. For half-duplex channels, install the receive frequency and other instructions exactly as described for simplex programming, but before pressing 2ND and LOAD (to store), continue by pressing 2ND and FREQ. This action will cause the XMIT indicator to blink and the FREQ indicator to illuminate. Enter the desired frequency and then push 2ND and LOAD to store channel data. Continue for channels 00 through 99.
To monitor the transmit frequency of a half-duplex programmed channel before transmitting, press 2ND and FREQ while in normal receive mode. The display will change to indicate the transmit frequency, and the receiver will simultanously switch over to operate on the transmit frequency. Press 2ND and FREQ to “toggle” back to normal operation. The XMIT indicator will stop flashing and the receiver will again operate on the receive frequency.
There are at least two versions of the EPROM program for the radio’s Control Board microprocessor. The version may be determined by examining the labels on the three EPROM chips after lowering the front panel. The EPROMs are 28 pin DIPs located in the upper right corner.
Note that this feature does not work with version 601F EPROMs, but works well with version 604M EPROMs.
Harris Radio
Ken, KO6NO makes remote adapter boards for the RF-350K which work very well. Ken can also provide version 604M EPROMs.
K7RDG has Harris manuals and remote control software for the RF-350K on his website.
Harris RF-350K radios
Harris 1KW transceiver awaiting installation
