[R-390] Receiver sensitivity

[Drew P.]

Roger L. Ruszkowski wrote:

"The R390/A only tunes down to 500 Khz. So while you can dial it down under 
500Khz it is deaf. always has been likely always will be unless you do some very 
serious receiver changes. Don't ask me here. Those things are not allowed 
under the current administration and were even off limits under past 
administrations. Good Fellows do not do those kinds of things to boat anchors. But I 
digress."

Well, it is actually possible to get the R-390A to receive below 500 KC/s without 
tearing the radio up.  Stick an antenna lead in the RF Deck test point socket for the
third mixer grid.  Signals will roll in, though with much trash because of no selectivity
between antenna and mixer. For appropriately enterprising souls, it should be reasonably
easy to cobble together a tuned circuit for use here.  Howzabout plugging a tuned loop 
antenna into the test point socket?

Anyone here on the list made it work reasonably well?

Roger, thank you for the specific and succinct information on measurement of sensitivity.
You are a wealth of information on these radios.

Drew