Just got a bunch of old radio transformers from an old closed shop. What is the best way to test them to see if they are worth keeping? Think I know,but not sure if I have sood enough test equipment. Would rather ask than be sorry!!

:Just got a bunch of old radio transformers from an old closed shop. What is the best way to test them to see if they are worth keeping? Think I know,but not sure if I have sood enough test equipment. Would rather ask than be sorry!!

Mike,

You'll need to know what type they are - power, interstage, audio, choke, etc. - in order to use or test them. Are they loose transformers or are they boxed/labelled?

mike e,

You may want to check out:

http://www.nostalgiaair.org/References/rmacodes/

If the transformers are new old stock (NOS) that reference may be helpful in identifying the lead colors for power transformers, IF transformers, output transformers, etc.

Radiodoc
************

:Just got a bunch of old radio transformers from an old closed shop. What is the best way to test them to see if they are worth keeping? Think I know,but not sure if I have sood enough test equipment. Would rather ask than be sorry!!

All transformers are loose,some with just 2 wires, some with 4, and some with several wires. none are boxed and labeled,but I can see what appears to be a part number. I thought maybe of doing a continuity test may render some results???

:mike e,
:
:You may want to check out:
:
:http://www.nostalgiaair.org/References/rmacodes/
:
:If the transformers are new old stock (NOS) that reference may be helpful in identifying the lead colors for power transformers, IF transformers, output transformers, etc.
:
:Radiodoc
:************
:
::Just got a bunch of old radio transformers from an old closed shop. What is the best way to test them to see if they are worth keeping? Think I know,but not sure if I have sood enough test equipment. Would rather ask than be sorry!!

Mike, well the two wires are most likely chokes, four wire mort likely output as power transformers usually have HV plus filament windings. If wires total to odd number you have a CT secondary. All can be checked with ohmeter. Should check all from wire to the frame to eliminate any that are shorted to gnd. Next use ohmeter to pick out pairs (windings). If you run across one with no matching pair, there is most likely an open winding. If they "pass" the above tests, then check resistance between pairs. Primary and secondary windings (HV) will be relatively high and secondary for filaments low. For those where you have three leads with continuity between them, one lead center tap That lead (CT) should read same resistance between other two leads. Problem you will have is the capacity of transformer (Watts). Hopefully there are some stampings on the frame to give you a hint. PL

:
:All transformers are loose,some with just 2 wires, some with 4, and some with several wires. none are boxed and labeled,but I can see what appears to be a part number. I thought maybe of doing a continuity test may render some results???
:
:
:
:
:
:
:
:
::mike e,
::
::You may want to check out:
::
::http://www.nostalgiaair.org/References/rmacodes/
::
::If the transformers are new old stock (NOS) that reference may be helpful in identifying the lead colors for power transformers, IF transformers, output transformers, etc.
::
::Radiodoc
::************
::
:::Just got a bunch of old radio transformers from an old closed shop. What is the best way to test them to see if they are worth keeping? Think I know,but not sure if I have sood enough test equipment. Would rather ask than be sorry!!

: Mike, well the two wires are most likely chokes, four wire mort likely output as power transformers usually have HV plus filament windings. If wires total to odd number you have a CT secondary. All can be checked with ohmeter. Should check all from wire to the frame to eliminate any that are shorted to gnd. Next use ohmeter to pick out pairs (windings). If you run across one with no matching pair, there is most likely an open winding. If they "pass" the above tests, then check resistance between pairs. Primary and secondary windings (HV) will be relatively high and secondary for filaments low. For those where you have three leads with continuity between them, one lead center tap That lead (CT) should read same resistance between other two leads. Problem you will have is the capacity of transformer (Watts). Hopefully there are some stampings on the frame to give you a hint. PL
:
::
::All transformers are loose,some with just 2 wires, some with 4, and some with several wires. none are boxed and labeled,but I can see what appears to be a part number. I thought maybe of doing a continuity test may render some results???
::
::
::
::
::
::
::
::
:::mike e,
:::
:::You may want to check out:
:::
:::http://www.nostalgiaair.org/References/rmacodes/
:::
:::If the transformers are new old stock (NOS) that reference may be helpful in identifying the lead colors for power transformers, IF transformers, output transformers, etc.
:::
:::Radiodoc
:::************
:::
::::Just got a bunch of old radio transformers from an old closed shop. What is the best way to test them to see if they are worth keeping? Think I know,but not sure if I have sood enough test equipment. Would rather ask than be sorry!!

Mike, your question is a difficult one to answer but a good one anyway.
First If those "transformers are in good physical shape then they are worth something.
Second If u can get ahold of some old transformer catalog pages to exactly identify them, that would be the best.
Third, this is the hard part - Without being able to identify them, the way that you test a transformer winding beside the continuity check is to: connect a 120v power line to the winding with a 120v light bulb in the line. This is a dangerous procedure if you dont know exactly what you are doing so check out the "dim bulb tester" on this site and similar "testers" on other sites. Use a socket for the bulb and start with a small wattage bulb (15 - 25 watt). If the bulb lights up to full brightness the winding is either shorted or is a low voltage winding (for a tube filament or speaker). If the bulb is dim then there is continuity but some reactance limiting the current. BTW this is basically how the old boys tested any kind of inductive winding. I.E. Motors,ballasts for flourescent lights,almost any kind of winding with a lot of turns.
Next You can connect the output of a 6.3 volt filament transformer to one of the windings and connect an AC voltmeter to the other windings and read the voltage. the voltage ratio is equal to the turns ratio. By doing this on all the windings one at a time you can usually find the primary - the winding that gives about 117 volts ac on the meter. Once you have identified the primary, and everything else is ok, then you can connect it directly to the ac line and find the secondary voltages.
BE EXTREMELY CAREFULL If you have never done this kind of thing before get some experienced help doing it.
There is one last option. This involves just using the core and winding your own primary and secondary on the core so that you will know exactly what you have because you made it. Luck