The AM Forum

Pins 1-3 Im reading 232 ohms manual says 370
pins 4-5                65 ohms  manual says 150 thats with all wires disconnected and DMM
Is this typical readings with DMM?

232 ohms and manual says 370 ohms,  something not right.  Readings shouldn't be off more than 10%.

65 ohm reading and manual says 150 ohms, something not right here too.  Recheck your measurements.

Doesn't matter what type meter you're using.

Fred

I had the same thing happen with my DMM. The batteries were weak. Try another meter or new batteries.

The ratios between pri and sec aren't too far off.  Also remember specs don't always match several years manfacturing run where different wire sizes may have been wound.  There may be a history for your model.

Just hook up a 6.3 fil xformer to one side and see if voltages match the turns ratio.
If they do and there are no shorts to ground / case and your sure it's a mod xformer (min. Two taps one side, three the other, etc. and with the three terminal side having a center tap showing the same resistance both sides of center tap) then use it.

I usually measure stuff with two or three VTVM/dmm/vom instruments when looking at old stuff.  I have a beautiful B&K in a leather case that was my gold standard,complete with HV probe, for years before I got my first DMM. 

As previous. mentioned, they all take batteries for some function or other, even the Heath VTVM.

K5YGC,
Are you having a problem with your transmitter, that you are suspecting a defective mod trans.?
These are military beasts that are hard to break.
That mod transformer will sound amazingly close to broadcast quality just as it is. Timtron proved that out during the late 90's with his famous audio mods. The 4-250's are good mod tubes also.
Tell us what is going on with your unit
Fred KC4MOP Fred

Thanks for all the replies I just acquired the T-368 and most of the wires on the mod trans. were cut made me think it might be bad.And my VTVM doesnt read ohms correctly so was hoping the DMM was giving false readings.There was some other wires cut and rerouted that made no sense  at all .One was S7 was missing and someone connected one end to the screens of the mod tubes and the wiper of the bias pot was connected to J2 pin 13.
  I have rewired it all and still hoping the mod tranny is good and will test it with the filament transformer thanks for the the help guys and will keep you posted. Mark K5YGC

Don't you just love undocumented modifications Mark? 

The small xfmr to check the voltage ratios is a good idea.
I like to use 10vac, since that makes the readings simple, not much math.

You can also figure out the ratios, and set up a test jig to run it with AC or DC at higher voltage. The DC will show if there is leakage to the secondary. Or the other way around, depending on where you apply what voltage. Current should be limited, you want more like a hipot test.

The previous owner may have had problems with the unit, and was trying to figure it out. I don't have the schematic open, so I don't know what the wires you mentioned were going to, or which wires were cut, etc. That might be a clue.

I would check for low Z readings between windings, and definitely between primary and secondary.

There are several different manuals for the T-368 and was looking to figure out what S-14 is for on the cabinet and found some more resistance readings and it says T-5 for A model is reading exactly what mine is reading. B&C models have higher resistance readings.Still not sure why he cut the wires or why he connected the interlock to the screens of the modulator tubes or the modulator bias to the plate relay pin 4.I have a few ideas but shouldn't say on the forum.Now I can put the mod tranny back on the deck and wire it up.When all else fails RTM but make sure its the right one. Thanks for all the help 73 Mark K5YGC