Philco 76 output transformer #2848
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
So I have the field coil done(my first), But I also have an open side in my output transformer. Since I have not been able to find a suitable replacement, I am thinking I will attempt to rewind. I am NOT up on transformers. After watching and reading everything I can find, I came up with this conclusion. This transformer has an 80:1 ratio. 80 turns on the primary to every 1 turn of the secondary. Now if I copy that, as best I can, will that work?
Stan
(This post was last modified: 12-10-2020, 09:46 AM by Stan the Man.)
Posts: 7,301
Threads: 269
Joined: Dec 2009
City: Roslyn Pa
You may want to have a look at this: https://philcoradio.com/phorum/showthread.php?tid=17572 around post 12/13 or so. Most of it's abt the input transformer but the mechanics of it is the same. Take it apart, count the turns and layers rewind accordingly.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
Thank you for the link, and the reply. I unwound the primary yesterday. It was not pretty. The transformer was impregnated with a waxy substance, and there were spots of corrosion all over. As soon as I would get it started unwinding, it would break. It became impossible to count turns. And by that time I was so aggravated, I forgot what layer I was on. Now I have a clean-er core, and a nice secondary winding. All I need is the primary.
Stan
Posts: 1,262
Threads: 32
Joined: Jan 2014
City: Wellborn Florida
You know the wire size might take all the pieces of the pri. wire and measure the total length add enough for few extra turns and give it a try. Much easier to remove a turn than add a turn. Gook luck David
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
David,. I'm gonna say the wire is 38ga. As for measuring the length, I would say thats not possible now. I can still see the imprint of the wire on the core. So I know how wide the layers will be. I can easily count the secondary wire turns. So I should be able to come up with something close. I just wanted to know if I was on the right track.
Stan
Posts: 1,262
Threads: 32
Joined: Jan 2014
City: Wellborn Florida
I have not looked but is there a spec on the resistance of the primary if so then look up the resistance per 100 feet of 38 ga or something like that an guess at the length add a little extra. Stay Safe David
Posts: 16,510
Threads: 572
Joined: Oct 2011
City: Jackson
State, Province, Country: NJ
Stan, get a Core!
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
I don't seem to be able to find a spec for the transformer, other than its 80:1 ratio.
My core is still very much intact, with the secondary still in it. I have ordered wire, and I have a cheap coil winder, so we will see what happens.
Stan
Posts: 2,118
Threads: 112
Joined: Jun 2010
City: Medford OR (OR what?)
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
Posts: 7,301
Threads: 269
Joined: Dec 2009
City: Roslyn Pa
Ed sez: I'm now finishing up the O/P transformer. Primary is done (#35 wire, 20 layers of 140 turns each with center tap). The secondary will be next. That is 18 AWG - incredibly beefy considering the voice coil of the speaker!
This = a primary of 5.2k load for the p/p 42's in a triode reconfiguration (Ed's 16X). Your 45's require a bit of a lower load abt 3.2k so a little less wire/turns. [Image: https://philcoradio.com/phorum/images/sm..._smile.gif]
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 12-11-2020, 11:42 AM by Radioroslyn.)
Posts: 4,896
Threads: 54
Joined: Sep 2008
City: Sandwick, BC, CA
I was going to suggest cleaning up the old wire from the wire from the primary, removing the wax, and weighing it. That's an alternative method to measuring the length if you can figure out how much a foot of a given gauge of wire weighs, though it is not easy without something like a chemist's scale.
Regards
Arran
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
Arran, The thought did occur to me. For reference sake. Whatever is on that wire was all over my hands by the time I was finished. What a sticky mess. If I thought I would be able to clean the wire and get a good weight that might be worth a shot.
Stan
Posts: 2,118
Threads: 112
Joined: Jun 2010
City: Medford OR (OR what?)
A person generally does not have to worry about getting too much wire on the form unless they use much smaller wire. If laid down neatly in layers, there is generally enough space. If bulk wound or wrapped with anything thicker than stock - no way.
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
Posts: 64
Threads: 10
Joined: Nov 2015
City: Memphis,Tn
Users browsing this thread:
|
|
Recent Posts
|
|
The list of my radio & TV collection!
|
| A little light Saturday positive about our hobby in our feed...
My new every Saturday video about antique radio equipme...RadioSvit — 02:12 PM |
|
Model 70 Cabinet Trim
|
| musar ,
Well if you have any more questions feel free to post away .
Sincerely Richardradiorich — 08:56 PM |
|
Model 70 Cabinet Trim
|
| Although I have not made any cabinets or cabinet parts for a couple of years, I still have some parts left over, includi...Steve Davis — 06:26 PM |
|
philcorepairbench.com - shadow-meter
|
| Thanks Ron. But I can't find those articles.fenbach — 02:43 PM |
|
Model 70 Cabinet Trim
|
| Thank you, Gary. Before making my original post, I had clicked on "Steve Davis Cabinets" only to find that it...musar — 02:25 PM |
|
philco predicta
|
| Welcome to the Phorum, cgl18! I am not your resource for television repair, but lots of friendly help is available here...GarySP — 02:12 PM |
|
Model 70 Cabinet Trim
|
| Welcome to the Phorum, musar! You can send Steve Davis a private message (PM). The site is at the top of the Home page...GarySP — 02:09 PM |
|
Model 70 Cabinet Trim
|
| How do I contact him? The only contact information for him I could find when searching online was a telephone number th...musar — 10:38 AM |
|
philco predicta
|
| Hello, good afternoon, I would like to ask what the possible problem could be if I don't have an image on the screen. I ...cgl18 — 10:19 AM |
|
Philco model 38 code 121 not receiving signal.
|
| So one last question before I finish this radio. Regarding the speaker and output transformer. I salvaged the original o...Stormlord5500 — 09:31 AM |
|
Who's Online
|
There are currently 1218 online users. [Complete List]
» 1 Member(s) | 1217 Guest(s)
|
|
|
|
 
|
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
