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All, Question about the OSC coil.. Do I bake it before or after rewinding the tickler coil?
Do the other coils get backed too? Or just the OSC Coil.. My radio uses a 36 for OSC Tube.. and is the 2 band..
How do you bake it I heard in a 200 deg oven for ??? Minutes...
Skip
(This post was last modified: 10-17-2018, 05:05 PM by vecher.)
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http://philcoradio.com/phorum/showthread.php?tid=13729
See Rons answer here on baking a coil. second post
Hope this helps you.
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Skip,
I have "baked" other coils, in a Zenith T.O. a Hammarlund Super-Pro and a Grunow. All with good results, in fact for the Zenith and the Hammarlund, both radios were completely placed into the oven after removing all plastic and rubber parts, dials, speaker, etc. They were in the oven until the wax started to flow. The concept was to drive out any moisture in the coils and raise the "Q". No resistances were taken as I did not expect them to change. What I expected and what happened was a much sharper response in alignment a noticeable increase in sensitivity.
For the Grunow the oscillator coil was fully re-wound for the BC/Police band, completed coil was immersed in hot bees wax and placed under vacuum for about 30 minutes until all bubbles ceased, vacuum release, coil set aside to cool, coil returned to hot wax for two quick wax coating dips. Radio aligned, coil was no more than 1/2 turn on alignment screws, worked perfectly.
What happen during the rewind of the Grunow was the removal of a cellulose acetate primary/secondary liner and replaced with thin plastic film. It was that liner than caused corrosion to the primary, the bottom layer.
I do not advocate placing an entire Philco chassis into an oven because a chassis may have coils wound with the cellulose plastic liner. Cellulose acetate is very flammable, that could be a disaster!
As for a rewound coil as long as the liner is gone then heating in an over for the 1/2 hour would seal the windings with the remaining wax and drive out any moisture in the entire assembly. IMHO that is a good thing.
YMMV
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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Ok, I sent out the 2 coils for repair.. When I got them back rewound..
The OSC coil had the Tickler coil rewound The schematic say winding should be 5.25 Ohms.. Mine is 2.0 ohms..Big Difference Is this going to cause problems??
The detector coil the primary was open.. Should be 1.68 Ohms After rewind Mine reads 1.0 ohms.. That may be OK ???
Skip...
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Depends on the size of the wire used. Resistance doesn't matter much it's the inductance that does.
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
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Ok here is what I get on my Chinese Meter..
OSC Coil Pin 1-2 2.3 Ohms .03 mH This was rewound
Pin 3-5 6.3 Ohms .27 mH
Ctr wire to OSC tube to Pin 4 5.1 Ohms .17 mH
Detector coil
Pin 1-3 1.4 ohms .01 mH This was rewound
Pin 2-5 8.6 Ohms .40 mH
Pin 4-5 6.6 Ohms .28 mH
Pin 4-2 2.3 Ohms .06 mH
I have no clue what size wire was used
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(This post was last modified: 06-24-2018, 02:03 PM by vecher.)
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That makes us even cause I have no idea have the original inductance was.
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
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Joined: Mar 2015
City: Lansdale
State, Province, Country: PA
Ok, I guess I will have to put them in and try it.. So on to recap..
Skip...
Posts: 933
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Joined: Mar 2015
City: Lansdale
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Ok, Working on the Filter Caps.. They are Electrolytic (according to schematic) 6uf at ??? Voltage..Question can I use 10UF at 450Volts.. Or does the first one need to be closer to 6UF
Skip
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(06-24-2018, 04:17 PM)vecher Wrote: Ok, I guess I will have to put them in and try it.. So on to recap..
Skip... Yep,
Unless you have NOS or the skills/materials to replicate the part, its the only game in town...
10 mf for a 6 is O.K. (unless there is a small cap across the associated inductor). If so try to get closer to the 6mf.
Upon first fire up, monitor the B+ at the 10 (6) mf cap. Some sets the B+ will rise above the 450 for a (scary) bit of time. These new electrolytics are no where as robust as the wet (liquid filled) electrolytics...
YMMV
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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(05-02-2018, 08:27 PM)Chas Wrote: For the Grunow the oscillator coil was fully re-wound for the BC/Police band, completed coil was immersed in hot bees wax and placed under vacuum for about 30 minutes until all bubbles ceased, vacuum release, coil set aside to cool, coil returned to hot wax for two quick wax coating dips. Radio aligned, coil was no more than 1/2 turn on alignment screws, worked perfectly.
Chas
Chas,
What kind of a vacuum pump/assembly do you use for your coil work? I would be interested in hearing suggestions and finding something like this. Any pics to share? Thanks.
Gilbert
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Vacuum pump was yard sale find, bell jar was explosion proof mercury vapor glass, vacuum plate was 3/8" thick, 11" round aluminum salvage. Installed three feet of 3/8" thread bolts for leveling. Put 1/4" NPT thread in center of plate 90 deg brass fitting to 1/4" poly tubing to pump with tee and vacuum release valve. Used cranberry sauce can to hold wax melted on stove with coil in the wax. Bees wax was from arts/craft store, 100% pure... No pix of coil, in radio and at customer, all equipment currently in storage.
Wax stays melted for a long time in vacuum...
GL
Chas
Shop at industrial salvage yards and factory building demolition for stuff like I found...
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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City: El Cajon, CA
Thanks for the info Chas! Some good info there to round up parts to build one!
Gilbert
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City: Gap Mills Wv 24941
and you could put 2 10uf in series to get just under 6uf.
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Ok Almost done with wiring.. One last problem.. The volume control..
Its reading approx 850K Ohms.. Should be 350K Ohms.. Looks maybe original But it has a part number of 3297Philco then under it it says 335007.. This number doesn't seem to match anything Its just a volume control NO Switch The Band switch is separate..
Will this work?? I can supply a picture if needed..
Skip...
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