I was setting up to operate the ARRL VHF Contest this past weekend and had the idea of also using my recently purchased IC-7300 as a Panadapter/Band-Scope to monitor the Receive IF Outputs of my VHF/UHF transverters. I don’t have much experience using Band-Scopes and figured it might be helpful, and that it should work since a VHF band is converted to a 28 MHz IF, and the IC-7300 could be set up to show 200 KHz of that 28 MHz IF output on its Band-Scope screen.
While I was cabling it to my transverter control box I thought to myself it could be very bad if I should accidentally find a way to transmit on the IC-7300 up into my transverters’ RX outputs and also into my main JRC IF transceiver’s receiver. It only took a half hour to make up the Receiver Protector in the picture, and it turned out that I was actually glad I did. At several points due to inactivity on the IC-7300 controls its screen timed out and went blank with the power button flashing, so I tapped the power button for the display to come back to life. About the third time I did that, I accidentally also hit the “Transmit” button which is immediately below the power button and the IC-7300 went into transmit. Within a couple of seconds I hit that button again to stop it from transmitting, and thankfully no harm was done. Funny that I had forgotten all about the front panel transmit button when I was removing my microphone and hand key connections. Maybe it didn’t actually transmit much as its mode was set to SSB with no microphone connected and the power turned down, or possibly there was a small spike and the Receiver Protector actually did what it was supposed to do.
My conclusion was that having a Band-Scope was in fact helpful, and the under $1K brand new deal I got on my IC-7300 from DX Engineering was now even sweeter in that it added a Band-Scope to my existing VHF/UHF setup. The Contest was however as lackluster as January VHF contests typically are, with the highlights being some microwave enhancement/scatter during the heaviest part of the snowfall, and working a Rover on 50/144/222/432 MHz with “no gain” horizontal omni loops on his vehicle up on Hogback Mountain in FN32.
This type of receiver protector could be helpful with separate receive antennas for the low bands, and also to protect an SDR dongle being used as a Band-Scope with a PC. The “Antenna” jack in my case was the end connected to the potential RF source, my IC-7300. The “To Receiver” end went to my IF connection to protect the transverters’ IF outputs and the IF transceiver’s receiver input. It’s a very simple circuit which in testing both in the line, and out of the line, showed no receive loss while receiving a weak VHF beacon on the IC-7300 via the transverter, visually looking at the CW characters formed on its waterfall display as well as just listening to the beacon on the IC-7300. The beacon was the same strength with and without the Receiver Protector.
Best 73, Chris WB2VVV
