Switching Relay Mistake

[k7iou]

One more suggestion when wiring up new antenna relays, if not already suggested, is to ohm out the connections with an analog ohmmeter before you put RF to the relay.   Confirm the goesintos and goesoutofs are wired correctly when keyed/unkeyed.  Then there is no need for adding light bulbs to RF inputs, which just IMHO, adds another future failure point.

That is the idea, to have a failure point if You accidentally applied TX into the RX or if you had a malfunction that caused the issue.

I do like the add-on box however.  Also I believe a 47 lamp would be fine for a boatanchor receiver, however I would use a low current fuse between 1-10ma for a solid state receiver.  

I have never TXed into a receiver before but I once smoked an antenna analyzer front end when I forgot to disconnect it from an antenna and then transmitted into an adjacent antenna.  Another lesson learned in the "Stupid Things Done With Transmitters" book

Peter

[K4RT]

Then there is no need for adding light bulbs to RF inputs, which just IMHO, adds another future failure point.

The purpose seems to be to add an inexpensive failure point that is easy to repair. I may try it myself. Would that circuit attentuate receive signals to any degree?

[k7iou]

Ken, the circuit didn't reduce my receiver sensitivity one bit. I built and put it in line due to using a dowkey relay and wanted a safety device to protect the receiver in case of malfunction or operator error. I chose the #47 bulb over the #12 due to cost and availability. The specs of the two bulbs are identical.
73 de k7iou