Have a question in regard to the output section of a model 600 or also a Gringsley- Grunow model 103a,230a. What my issue is does anyone know the value of the R.F choke coil and also the transformer that feeds the 245 output tube. I have an issue with either transformer or RF choke after the last 224 tube that feeds the 2 245 output tubes. I can bypass and get to work with cap and resistor but only have one 245 tube work at onces. Any ideas?

Thanks
Mike

If you go on eBay right now

http://shop.ebay.com/items/?_nkw=majestic+transformer&_sacat=0&_fromfsb=&_trksid=m270.l1313&_odkw=majestic+radio&_osacat=0

you will find for sale two model 70 interstage transformers, which will likely work for your radio as well. I asked him if these are in fact interstage transformers, and that one of them is NOT an output transformer. I am waiting on an answer. In my Majestic 180 the output transformer has rather thick primary leads, since it handles over 400 volts. I assume that others would have rather thick leads, too, though not necessarily. The interstage transformers in these radios are similar. Make sure, though that you get the one with the correct ratio for the stage you are working on. The two he lists have different ratios. You could purchase both if you wanted to.

Also, if the primary of your transformer is open, but the secondary is not, you can possibly make the radio work just fine with the existing transformer. You might not have as much gain, though. What you can do, however, is connect the plate of the 27 to B+ through a suitable plate load resistor (100K or higher, to suit your audio tastes....higher will give more gain and more bass, though too high might not work well.....you can also consult a tube manual and try to match that). Then feed one half of the transformer secondary from the plate of the 27 with a capacitor around .02 MFD. Adjust to suit your taste. Also connect that half of the secondary to one of the 45s. Connect the center tap to B- as it was originally. Connect the other half of the winding to the other 45. Through transformer action (much like an ignition coil, where the two coils are connected together, also known as an autotransformer), the other half of the secondary not connected to the 27 will receive an inverted signal.

T.

General interstage transformers are also available through www.tubesandmore.com. They can be hidden inside of the original units if desired. Be sure to match the original ratio if possible.

T.

:General interstage transformers are also available through www.tubesandmore.com. They can be hidden inside of the original units if desired. Be sure to match the original ratio if possible.
:
:T
Hi and thanks for the reply I looked at the site you put on but an not sure they will match what I need. The problem is most details for these radios give any detail on that transfromer. I do not know of the model 70 at all and cannot find any details on it. I bevlive if the last tube is a 224 feeding 2, 245 it may work but not sure what the model 70 is. I belive it is older then the one i am looking for . most models from 29-30 had this config. Just to let you know the radio is working so the primary trans is gone but set up with a cap and resitor to one 245 but would love to get both working. Thanks again for your help in this matter. if anyone could tell me the number of turns or what this tranformer is i may be able to get it rewound.
Thanks

Mike

::General interstage transformers are also available through www.tubesandmore.com. They can be hidden inside of the original units if desired. Be sure to match the original ratio if possible.
::
::T
:Hi and thanks for the reply I looked at the site you put on but an not sure they will match what I need. The problem is most details for these radios give any detail on that transfromer. I do not know of the model 70 at all and cannot find any details on it. I bevlive if the last tube is a 224 feeding 2, 245 it may work but not sure what the model 70 is. I belive it is older then the one i am looking for . most models from 29-30 had this config. Just to let you know the radio is working so the primary trans is gone but set up with a cap and resitor to one 245 but would love to get both working. Thanks again for your help in this matter. if anyone could tell me the number of turns or what this tranformer is i may be able to get it rewound.
:Thanks
:
:Mike

Sorry forgot to say as well I had this radio into someone who knows about radios from this vintage and he said it was the RF coil that was bad but I belive it is the tranformer before it. Does any one know if this is a standard RF coil or differnt depending on design for this vintage radio. Again around 29- 1930 model 600 or around that vintage.
Mike

The model 70 is from about 1928. Most, if not all, of those radios from that period use those box style interstage transformers. An interstage transformer from a model 70 will likely work fine in your radio, too. The problem is that the guy who is selling those transformers doesn't know which one is which. You could buy them all if you wanted, but if you measure the resistance of the remaining winding on your broken transformer, you might be able to get him to find the transformer in his batch with a similar resistance winding. I can also measure the transformers in my model 180. My 180 uses #27 tubes, which originally fed two #50 tubes. Now I am using #45 tubes, especially since the original power transformer is gone.

You can find your schematic under Grigsby Grunow in the REsources section of this web site.

T>

:The model 70 is from about 1928. Most, if not all, of those radios from that period use those box style interstage transformers. An interstage transformer from a model 70 will likely work fine in your radio, too. The problem is that the guy who is selling those transformers doesn't know which one is which. You could buy them all if you wanted, but if you measure the resistance of the remaining winding on your broken transformer, you might be able to get him to find the transformer in his batch with a similar resistance winding. I can also measure the transformers in my model 180. My 180 uses #27 tubes, which originally fed two #50 tubes. Now I am using #45 tubes, especially since the original power transformer is gone.
:
:You can find your schematic under Grigsby Grunow in the REsources section of this web site.
:
:T>
Seems like the only model from that time period with the Grigsby Grunow seem to be the 233 230a and 130 a with the same tranformer output. Does anyone else know of any others that may work with an output from a 224 tube to 2-245 tubes thanks again

Mike

::The model 70 is from about 1928. Most, if not all, of those radios from that period use those box style interstage transformers. An interstage transformer from a model 70 will likely work fine in your radio, too. The problem is that the guy who is selling those transformers doesn't know which one is which. You could buy them all if you wanted, but if you measure the resistance of the remaining winding on your broken transformer, you might be able to get him to find the transformer in his batch with a similar resistance winding. I can also measure the transformers in my model 180. My 180 uses #27 tubes, which originally fed two #50 tubes. Now I am using #45 tubes, especially since the original power transformer is gone.
::
::You can find your schematic under Grigsby Grunow in the REsources section of this web site.
::
::T>
:Seems like the only model from that time period with the Grigsby Grunow seem to be the 233 230a and 130 a with the same tranformer output. Does anyone else know of any others that may work with an output from a 224 tube to 2-245 tubes thanks again
:
:Mike

Forgot to ask as well does any one have the drawings for a model 70 Grigsby-Grunow radio.

Thank again
Mike

This is a model 70, which uses the box style transformers:

http://www.nostalgiaair.org/PagesByModel/002/M0040002.pdf

This is a model 90, which uses pretty much the same transformers, and uses p-p 45 output:

http://www.nostalgiaair.org/PagesByModel/017/M0040017.pdf

FOr more schematics, go to the REsources section of this web site and look under Grigsby Grunow.

T.

:This is a model 70, which uses the box style transformers:
:
:http://www.nostalgiaair.org/PagesByModel/002/M0040002.pdf
:
:This is a model 90, which uses pretty much the same transformers, and uses p-p 45 output:
:
:http://www.nostalgiaair.org/PagesByModel/017/M0040017.pdf
:
:FOr more schematics, go to the REsources section of this web site and look under Grigsby Grunow.
:
:T.
Can I ask a simple question in regard to this subject. Is there a standard choke coil that feeds the 245 tube and tranformer that feeds those same tubes does anyone know?the setup is the same for a lot of models from that time period so they must use the same type of choke and tranformer to feed them.
Thanks

Mike

To all thanks for the assit in this issue. I have found someone to reslove this issue. I have taken this radio to Granpa's radio for this transformer. He knows the transformer needed for this radio. He also doing the full restore on this radio.
If you ever need assit on your radio you may want to get ahold of him.
Mike

::This is a model 70, which uses the box style transformers:
::
::http://www.nostalgiaair.org/PagesByModel/002/M0040002.pdf
::
::This is a model 90, which uses pretty much the same transformers, and uses p-p 45 output:
::
::http://www.nostalgiaair.org/PagesByModel/017/M0040017.pdf
::
::FOr more schematics, go to the REsources section of this web site and look under Grigsby Grunow.
::
::T.
:Can I ask a simple question in regard to this subject. Is there a standard choke coil that feeds the 245 tube and tranformer that feeds those same tubes does anyone know?the setup is the same for a lot of models from that time period so they must use the same type of choke and tranformer to feed them.
:Thanks
:
:Mike