Receiver Saver Circuit

I recently assembled and delivered to W4BXI a customized version of a circuit developed by AD5X to permit the safe use of a secondary (spotting) receiver on its own antenna while operating a transceiver on a main antenna. The circuit is intended to protect the spotting receiver from excessive RF energy when the main rig transmits on its nearby antenna. The original circuit was published in the January 2008 issue of CQ magazine.

Here is a copy of the customized schematic, which adds a power switch, status indication LEDs, and supplementary protection elements.

Some views of the assembled unit are shown below.

W4BXI is testing this unit at his station, and I expect to incorporate some refinements as I get his feedback. One change may be to use shielded leads from the two SO-239 jacks to the circuit board, to improve the isolation between the receiver and the antenna when the receiver is grounded. Another change I am considering is the introduction of a time delay for restoring the antenna-to-receiver connection when the control signal changes to the receive state. A few seconds of delay here would minimize relay cycling if the operator is using full QSK, while not significantly affecting the utility of a spotting receiver.

BirmingHAMfest - May 3-4

BirmingHAMfest
Zamora Shrine Temple, 3521 Ratliff Road
Bell Ringer gathering:
Saturday, May 3 at 1:00 pm in forum room #2
Contact: John WA5MLF

WA9JNM -- Bell Ringer #322

Please welcome Steve WA9JNM as our newest member of the Bell Ringers. He is member #322. Steve is a frequent participant in our Saturday morning net and our weekday morning QSOs.

W4UOA presentation on Intermodulation Distortion and the 3rd Order Intercept Point

On April 14 Carl delivered this presentation to the Tuscaloosa Amateur Radio Club. Here is a photo taken at the conclusion of the session. W4BXI and WA5MLF attended, following a visit to Carl's hamshack

Photo from W0S Special Event

Here is a photo showing Sap along with visiting operators Fred and Smitty.
Additional photos are posted at a page of the Bell Ringers gallery.

W0S Titanic Special Event - April 12-13

The Titanic Special Event takes place this weekend, April 12-13. You can find most of the essential details on the Titanic Blog.

The home page includes this link to a live video stream.

Sap advises that the weather will again be frigid for this event. We hope that Fred & Smitty will enjoy operating the station under authentic Titanic conditions.

S-Meter Ham Radio Website

You may find this web site of interest. It was suggested a while back by Smitty. Here is a quote from the home page:

"Check your signal and listen to others on remote receivers. Read thousands of pages of ham radio information. Download virus-free radio-related design programs. There is no charge for receiver usage, any of the information, or any downloaded computer programs."