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GE 107 loop antenna replacement - Printable Version

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GE 107 loop antenna replacement - Tgace459 - 05-28-2016

I'm working on a GE 107 radio that has a loop antenna glued onto a wooden panel backboard. The antenna was rusted and popping off and the backboard was taped together and falling apart.

I made a replacement backboard and attempted to remove the loop antenna for a "transplant operation"...needless to say it's not looking good for the patient.

So. I'm thinking about attaching some short sections of wooden dowels to the board and wrapping my own antenna. But I've never made one before and am unsure of a few things...like what type of wire, how many wraps, etc.

The schematic specifies 2.5 Ohms for the antenna on this model. Do I just keep wrapping till I hit the Ohm target? i'm sure there is probably an equation where wire diameter, length and resistance can tell me how long of what size wire I need, but that math is beyond my current comprehension. Icon_smile

RE: GE 107 loop antenna replacement - Radioroslyn - 05-29-2016

The resistance means very little. Inductance is what you need to know. The short answer is to approximate total length of the wire that was used on the original loop. The gauge is not super critical but you don't what to use 10g where it had 30g. Wind a new loop and add 6" extra of wire to your loop. Connect it to your set and adjust the ant trimmer for a sharp peak. If you can't get a peak cut off 1" at a time till you do.

Simple right!!

Terry

RE: GE 107 loop antenna replacement - Tgace459 - 06-19-2016

So...I made a cardboard oval (approx 11" X 6") with an odd number of slots for winding and wound about 38 turns of 26 gauge enameled wire (70'-75'). I get one strong station and maybe 2 other weak ones. All down on the high end of the dial.

Is there any sort of "rule of thumb" to determine if I have too many turns or too few? It would suck to start chopping off wire only to find I didn't have enough in the first place.

RE: GE 107 loop antenna replacement - Radioroslyn - 06-20-2016

If it is only resonant at the low end of the dial the loop is too long.Too much inductance. There is a simple devise called a Grid Dip Meter (gdo) that can tell you at what frequency a coil/capacitor circuit is tuned to.
Chop some off.

Terry

RE: GE 107 loop antenna replacement - Tgace459 - 06-20-2016

Of course out here in Buffalo the only AM stations on the low end are 550 and 930 (and maybe 970??). I don't think we ever get anything else on that side of the dial....

RE: GE 107 loop antenna replacement - Tgace459 - 06-20-2016

Alright. I stopped by my home for lunch and tinkered while I ate.

I've removed about 3 turns and I am getting about 3 more stations between 1000-1520 MHz and I can hear 550 and 930 faintly.

Is there a point I stop taking off entire turns and tweak it in smaller increments?

RE: GE 107 loop antenna replacement - Radioroslyn - 06-20-2016

Your done when you can get a peak using the trimmer on the top of the tuning cap at the high end of the band. As you remove turns have the set tuned to a station at the high end of the band. That signal will get stronger and stronger then it will start to get weaker. You want at it's strongest.

Terry

RE: GE 107 loop antenna replacement - Tgace459 - 06-20-2016

Well.....things were going along OK then suddenly the radio went silent. The speaker only has a faint hum and as I adjust the volume I get small bursts of static and the pilot lamp dims. I think something @#$% the bed......