There are two schematics shown there on that print. A model 83 with push/pull and the model 63 single ended.
My question relates to what might that device be in the power transformer primary?
In the model 83 it is indicated as a #638 and there is no indication number for this same part on the model 63 print.
I can't imagine what this thing is except perhaps a lamp or ballast or something... but the dial lamps are only 6v and connected to the 6.3v winding.
This thing's symbol on the print is a resistor-looking thing drawn in a circle like a tube.
Could it be some kind of ballast-like thing?? But it doesn't seem that it ought be in the primary winding.
On my actual radio there's just a flat disc-like module on an octal base plugged into that octal socket with the number PB-18179 stamped on top.
The AC power input wires sort-of has leads connected to 2 pins on the socket of this thing but seems like it's only as tie points.
When I opened up this flat aluminum disc thing I see that it is empty.
So ofcourse leaving it out all together makes no difference ... but it just leaves an obviously empty socket on the chassis.
So.. what is it? ... or what was supposed to be there please?
It's a line ballast resistor. The idea being your radio should operate over a large line voltage range, maybe 90 - 130 volts.
Your power transformer is wound for 80 - 85 volts input. This ballast makes up the difference. Resistance of the ballast varies as it heats.
Norm
:I'm working on a Herbert Horn "Tiffany Tone" model 63
:That plays nicely now but needs further re-capping and clean up as I am following the messiest sloppy work done by a previous tinkerer in here.
:http://www.nostalgiaair.org/PagesByModel/072/M0009072.pdf
:
:There are two schematics shown there on that print. A model 83 with push/pull and the model 63 single ended.
:
:My question relates to what might that device be in the power transformer primary?
:
:In the model 83 it is indicated as a #638 and there is no indication number for this same part on the model 63 print.
:
:I can't imagine what this thing is except perhaps a lamp or ballast or something... but the dial lamps are only 6v and connected to the 6.3v winding.
:
:This thing's symbol on the print is a resistor-looking thing drawn in a circle like a tube.
:Could it be some kind of ballast-like thing?? But it doesn't seem that it ought be in the primary winding.
:
:On my actual radio there's just a flat disc-like module on an octal base plugged into that octal socket with the number PB-18179 stamped on top.
:
:The AC power input wires sort-of has leads connected to 2 pins on the socket of this thing but seems like it's only as tie points.
:
:When I opened up this flat aluminum disc thing I see that it is empty.
:So ofcourse leaving it out all together makes no difference ... but it just leaves an obviously empty socket on the chassis.
:
:So.. what is it? ... or what was supposed to be there please?
:
:
:
:
But if the primary of the power transformer was wound for 80-85vac.. then why does the print show 110vac at the primary winding?
And since I am running it at 125vAC typically.. should I be using that ballast?.. If I could even find one?
I see about 275-CT-275 AC on the plates of the 5Y3 now.
And about 188vdc B+ on the plate of the 6f6.
As Dennis said, maybe there was a revision along the way? The early transformer would have had a 80-85 volt AC input voltage. The ballast was used to drop line to this level.
Could your original transformer been replaced? If you ran 125 volts into the 85 volt winding voltage would be way too high and transformer might even buzz. (I've done this before.)
Norm
:Thanks Norm:
:
:But if the primary of the power transformer was wound for 80-85vac.. then why does the print show 110vac at the primary winding?
:
:And since I am running it at 125vAC typically.. should I be using that ballast?.. If I could even find one?
:
:I see about 275-CT-275 AC on the plates of the 5Y3 now.
:And about 188vdc B+ on the plate of the 6f6.
:
:
I meant that it is shown as 110vac right on the input winding on the SCHEMATIC:
http://www.nostalgiaair.org/PagesByModel/072/M0009072.pdf
..So it's the print that clearly shows the primary winding input voltage as 110vAC
So here's my question:
...if they were expecting 110 vAC as an input source why would they have also needed a ballast dropping element? That is what I'm not clear on.
ok... you meant that the original transformer was wound for 85volts.. and on the print they realized that 110v would be typically used as input therefore they included a dropping ballast to compensate.... Yes.. right of course.
An yes my transformer has been replaced... eliminating the need for the balast.
BUT... Norm... how did you know that the original transformer was 80 volts?
Was that a standard typical service supplied AC voltage back around that time?
I'm usually in a hurry, don't read or explain things very well. Thomas does a good job explaining.
It was fairly common for manufacturers to use transformers with 80-85 volt AC input. This information can be found on different manufacturers schematics. Atwater Kent, Majestic and others did this. In early days of radio the AC line wasn't held very steady. Turning on a light might drop line voltage.
These ballasts increase resistance as they heat. With higher line voltage drop is greater holding voltage to a transformer fairly steady.
Norm
:Norm:
:ooopsd... ok... now I get what you wre trying to tell me... lol..
:sometimes I'm a bit slow... DUH
:
:ok... you meant that the original transformer was wound for 85volts.. and on the print they realized that 110v would be typically used as input therefore they included a dropping ballast to compensate.... Yes.. right of course.
:An yes my transformer has been replaced... eliminating the need for the balast.
:
:BUT... Norm... how did you know that the original transformer was 80 volts?
: Was that a standard typical service supplied AC voltage back around that time?
:
:
:
Interesting ...........