A. What is the purpose of a .001 capacitor between the headphones of a crystal set? Another schematic for a crystal radio shows a 22K resistor across the headphones? What do these do? What would other values of capacitance or resistance do in that place.

B. Just purchased a 5 tube, 01A set, with the only name of Apollo on the front. The set looks homemade inside or home assembled. Any idea as to the actual maker and where from. The set is absolutely lovely and needs only 1 interstage transformer. Does anybody have one to spare? Cost to 56547?

Thanks.

Hi Del

A capacitor across the earphones bypasses RF but allows audio to be heard. Without this cap touching the headphones will change tuning of the crystal set. A larger cap will reduce high frequency audio response.

A resistor may be added when crystal type headphones are used. These don't have internal resistance which is needed to complete the circuit.

Don't know who made Apollo. A similar circuit schematic is available under Stewart Warner 300 series by clicking on Resources, above.

Replacement audio interstage transformers are available from AES, www.tubesandmore.com , Radio Daze, www.radiodaze.com and PTOP, www.oldradioparts.com . Use one similar to Stancor A53.

Norm

:A. What is the purpose of a .001 capacitor between the headphones of a crystal set? Another schematic for a crystal radio shows a 22K resistor across the headphones? What do these do? What would other values of capacitance or resistance do in that place.
:
:B. Just purchased a 5 tube, 01A set, with the only name of Apollo on the front. The set looks homemade inside or home assembled. Any idea as to the actual maker and where from. The set is absolutely lovely and needs only 1 interstage transformer. Does anybody have one to spare? Cost to 56547?
:
:Thanks.

Del,
You can get a new replacement transformer as Norm suggests and depending to the style you have, you may be able to hide the new one in the case of the old one to preserve the original appearance. The transformer coils are sometimes available too - in this instance you will re-use the iron core of the old transformer - but again, this will depend on the type transformer you have. If your transformer is of a common make, a new, old-stock or a good used one may be available from the sites mentioned by Norm Leal.

It is sometimes possible to get a little more life out of an old open interstage transformer by taking it out of the radio and briefly (up to about 5 seconds max) hooking up the open winding to a neon sign transformer. Sometimes this will fuse the break back together and should be suitable for an occasionally used radio. Only do this with extreme care and caution. It may take a couple of zaps to make it work. Check for continuity with an ohmmeter after each attempt. To lessen the possibility of damage to the neon transformer, I often leave a slight spark gap (1/8") between one of the transformer leads and the high voltage output of the transformer. I have used this method several times and it seems to work in about 50% of the transformers I have tried it on.

The old interstage transformer is gone entirely. I will get a new one from one of the sources. Thanks for all of your replies.

:Del,
:You can get a new replacement transformer as Norm suggests and depending to the style you have, you may be able to hide the new one in the case of the old one to preserve the original appearance. The transformer coils are sometimes available too - in this instance you will re-use the iron core of the old transformer - but again, this will depend on the type transformer you have. If your transformer is of a common make, a new, old-stock or a good used one may be available from the sites mentioned by Norm Leal.
:
:It is sometimes possible to get a little more life out of an old open interstage transformer by taking it out of the radio and briefly (up to about 5 seconds max) hooking up the open winding to a neon sign transformer. Sometimes this will fuse the break back together and should be suitable for an occasionally used radio. Only do this with extreme care and caution. It may take a couple of zaps to make it work. Check for continuity with an ohmmeter after each attempt. To lessen the possibility of damage to the neon transformer, I often leave a slight spark gap (1/8") between one of the transformer leads and the high voltage output of the transformer. I have used this method several times and it seems to work in about 50% of the transformers I have tried it on.

Del, if you can post a picture of what you have, it would be easier to direct you where to go in your search. Perhaps some poster to this site may even have what you need in his junk box...