[TimC]

Have a restored 38-610 console and am looking to connect antenna(s) for broadcast and shortwave reception.
Looking at the antenna terminals, have a "red", "black", "grnd" and "4". Labeled 1,2,3&4 respectively.
Currently have a jumper-bar between "black"(2) and "grnd"(3). As I recall, the jumperbar had something to do with a "short" antenna. Not sure of what I will use for antenna(s) but need to understand what the set wants first...
Also what impedance does the radio look for? 50 ohms?, 300?

Any info appreciated.
tim

[TimC]

I'll take it to be a mystery...
guess I'll experiment

[exray]

I'll take a little stab at it. Looking at the 37-610 schematic it looks like jumpering 3 and 4 allows connection of a balanced antenna (dipole/doublet) at 1 and 2. Flipping the jumper over to 2-3 should allow a random-length single wire to be connected at 1.

Impedance wise you can guess the balanced connection to be in the 50-100 range and the single wire connection to be >600 ohms up to a few k-ohms.