Philco 89 oscillator

1/22/2010 10:25:44 AMBrett

I removed the oscillator coil and baked at 200 degrees for 30 min. I cannot see any breaks in the winding but I'd like to test it further. Is there some sort of Ohms test I could do between the five soldering lugs and the wire to the top of the tube? Where should I get readings and what? thanks.

1/22/2010 10:53:32 AMBrett

O.K. if I'm reading this right I should get 5.2 Ohms between the lugs for the small outer winding. The first two clockwise from the clamp and connecting between the 77 tube and a cap and resistor. Right? I get nothing. Any pointers on how to rewind and what to use? Thanks again.

1/22/2010 10:53:32 AMBrett

1/22/2010 12:30:05 PMTerry Decker

:O.K. if I'm reading this right I should get 5.2 Ohms between the lugs for the small outer winding. The first two clockwise from the clamp and connecting between the 77 tube and a cap and resistor. Right? I get nothing. Any pointers on how to rewind and what to use? Thanks again.
:
Hey Brett-
I don't have the schematic for that set, so I don't know what you're looking at, but AES has 3 lug coils for 2 bucks. A replacement might be more reliable than a rewind. Just a suggestion.
terry

1/22/2010 12:31:30 PMThomas Dermody

Use very thin wire in the high 30s to 40 gauge. I do not know what the original wire is, but it's very thin. I used wire from the primary winding of an old AC/DC radio output transformer ...on my Philco 60. Works well.

Unwind the old coil and count the turns. Wind the new coil in the same direction as the old. If you accidently reverse connections, and the radio won't oscillate, you can reverse them again, later.

Why did you bake the coil?

1/22/2010 12:58:28 PMBrett

Baking the coil was suggested on philcoradio.com and apparently is common practice for Philco collectors. I presume it is to remove any moisture that may have accumulated in the windings and possibly reseal by reflowing the wax.
Any suggestions as what to use as an insulator between the primary and secondary coils? It looks like a quarter roll might work, but I don’t know if paper would be a good idea. Maybe electrical tape.

1/22/2010 2:03:15 PMMarv Nuce

Brett,
Double sticky tape might help to stabilize both the old and new windings, but research the insulating properties first. A lot of the coils in AM radio sets use Litz wire (several strands encased in a cotton wrapper), and have distinct advantages over plain enameled single strand wire. I have not personally compared 2 identical winds with each, but others on this Forum may have. The problem would be finding Litz wire of the proper gauge in the small quantities req'd for a reasonable cost. I found a couple by Googling Litz wire, but not the gauges I needed. I designed an Electro-Mechanical hand cranked winder to reproduce the lattice wind technique, and it worked well using cotton thread (similar to Litz), but when researching Litz, found it prohibitively expensive, and in quantities to large for a hobbyist. My winder sits idle, awaiting my next brain storm (fart)

marv

:Baking the coil was suggested on philcoradio.com and apparently is common practice for Philco collectors. I presume it is to remove any moisture that may have accumulated in the windings and possibly reseal by reflowing the wax.
: Any suggestions as what to use as an insulator between the primary and secondary coils? It looks like a quarter roll might work, but I don’t know if paper would be a good idea. Maybe electrical tape.
:
:

1/22/2010 4:42:16 PMBrett

Marv,
This is really fine. It looks to be about .010". I didn't mic it yet because I don't want to cut it until I have too. I thought someone who's done an 89 or 19 before might know the gage. It's gotta be up there.
Brett

1/22/2010 4:51:37 PMNorm Leal

:Marv,
:This is really fine. It looks to be about .010". I didn't mic it yet because I don't want to cut it until I have too. I thought someone who's done an 89 or 19 before might know the gage. It's gotta be up there.
:Brett
:

1/22/2010 4:55:21 PMNorm Leal

Hi Brett

Very common to have open oscillator coils in Philco radios. Sometimes you can see a green spot of corrosion. When you try unwinding some Philco coils the wire just falls apart.

If you only want the broadcast band AES and Radio Daze sells universal oscillator coils.

Norm

::Marv,
::This is really fine. It looks to be about .010". I didn't mic it yet because I don't want to cut it until I have too. I thought someone who's done an 89 or 19 before might know the gage. It's gotta be up there.
::Brett
::
:

1/22/2010 5:04:09 PMThomas Dermody

You should be able to successfully rewind this coil yourself. Replacement isn't necessary. Litz wire is not used. Use regular solid enameled wire. It will work very well.

1/23/2010 1:18:43 PMBrett

What gage wire should I use on a Mod. 89's primary coil?
Brett

1/23/2010 2:54:41 PMEdd

Sir Brett. . . . .

Same-Same . . . gauge as most honnable secondary . . . . should certainly be permissible.

73's de Edd

:What gage wire should I use on a Mod. 89's primary coil?
:Brett
:

1/24/2010 10:42:59 PMThomas Dermody

Is the primary coil blown? These are usually a much thicker gauge wire, and don't usually open up. The secondary plate circuit coil is up around 40 gauge, but the primary windings are more around 30 gauge or less. I'm not interested in opening up my Philco 60 at this moment, and certainly not interested in removing the coil, which is most likely similar to yours, since that style of coil was used in a lot of those radios, but that is what I remember about my coil.

1/25/2010 6:19:33 PMBrett

I cut and measured the wire at .004" according to the chart that makes it 38 gauge. As soon as it gets here I get to rewind my first coil.

1/25/2010 10:11:08 PMThomas Dermody

If you do a good job of repairing the rest of the radio, it should be a rewarding experience for you. Philco coils are easy to rewind. Recapping is a bit more difficult than with most radios (unless you restuff the capacitors in all of your radios). I was lazy and just operated my 60 with the original caps and some new electrolytics, and new tone caps because the originals shorted and blew the output transformer (before I got it), but the irratic performance eventually got so annoying that I have now begun to slowly recap it. Of first concern was the tin filter cap box. Major improvement with that done.

1/30/2010 2:58:37 PMEdd

Sir Brett . . . . . .

So . . . knew I wasn't too far off in that gauge requirement, and the additional fact of its fewer turns needed, by virtue of its specific application / function of being a cathode feedback link/winding.

There is but minimal current passage thru that winding.

The most critical winding is the one that is far right on the schema and is series resonating with the tuning condensers oscillator section.

As per "miking" the wire size . . . should I have been so lucky . . in my pre teen aged years, to have had such capabilities or even KNOWN anyone to borrow such from, being in a 1 stop sign, small town.

I was all left up to my own ingenuity , a referencing page from a 1932 Radio Amatueurs Handbook and scrounging of parts of old car radios from the junk yard . . . then using their magnet wire.

I would take an old transformer / speaker field coil / etc, and tear it down for its wire, CLOSE wind the wire on a large needle and fill an inch of coverage.

The magic Turns Per Inch number then is . . . .134 turns if #34 gauge . . or . . . 224 turns if #38 gauge.

The reason I am giving two sizes is in my referencing to the Radio Amateurs Handbook that is still the figures that I get.

But when looking up in newer referencing, I am not seeing a variance, with any numbers changing.
Since I was basically wondering about the replacement of common (old brittle) Enamel covering with Formvar and even MORE exotic coverings since Formvar’s introduction on the overall diameter affectation.

BUT . . .All numbers are still same-same.

In looking at my tables for actually miking the wire , its still telling me:

.006305 in for #34 enamelled magnet wire

and

.003965 in for #38 enamelled magnet wire

gauges.

Did you mike the wire right and interpret to wire size correctly BUT typed in the wrong gauge number ?

Or did you possibly confuzzzze mil dia / versus / circular mil area ?

Don’t worry since , I believe that you have a compatible work around with the size being received.

I remember many times in transmitter design / construction and needing a link to carry more current.

Since I had used a smaller gauge of wire on my resonating winding, I would go . . .a . .la . .Litz wire construction. . by using slightly twisted (3tpi) multiple (2 or 3 or 4)wires to upgrade current capability to the equivalent heavier gauge, by using ONLY the smaller gauge wire I had on hand, with minimal revision of overall turns being used.

I think the best facilitator that you can use in that rewinding process is the initial preparatory pulling of the length of wire used thru 2 beeswax blocks, on either side/or around the wire length being used.

That will give some WELL needed “stiction” to hold the wire in place in the winding process. Otherwise, you let tensioning off a bit and it then goes s . p . r . o . i . n . g.

I had used a beeswax candle for YEARS until my young g-daughter opted to use it and burned it ALL up, even down to the scorings on the very - very bottom, where I had been pulling my wire thru it.

A check at craft stores only found a somewhat high pricing of $12 for a small slab of beeswax, no luck at crafters candlemakers supplies as they all seem to have reverted to soy or common parrafin wax, of which, the latter is farTOO hard.

What I eventually used was something that I had noticed in "dreaded" plumbing repair.

("Dreaded", therewith described, as being an explosively exponentially increasing direct multiple reciprocity of the degree of olefactory displeasure being experienced. )

Seems like beeswax was listed on the packaging for the composition of the common toilet bowl sealing "O" ring that one puts down to the closet ring.

YOO-HOO . . . ONE big HUNK-O-WAX for a mere 2 Amellican Dollah !

That's what I have now been using for my beeswax, for Y- e- a- r- s.

Initially or from the get go, if pulled from OLD stock, (Po'dunk Holler Gen'ral Store) you just might find the "skin" too hard, but down inside there is the soft portion, or what I do is blend the soft and harder portions in hand, using palm heat to get it JUST right.

And then, after its use, sealing up in Saran wrap (a . . la . . blowing up a small paper bag to pop it . . ., but INSTEAD, HEAVILY inhaling to the max and and multi twisting the wrap to seal it, thus ending up with it being vacuum packaged and to facilitate for more temperate storage in the future .)

At the bottom I am placing ye olde handbooks Copper Wire Table, should anyone else need it for future referencing.

It worked GREAT in my early days, for this lil' ole' kid from a hard rock scrabble 'po lil Texas town.

Plus there is very little wire needed to get an inch of close wound wire on a needle, and then no ambiguity in the interpreting of the big jump in turns count when dealing with a difference of single gauge to gauge count spread.

E.G.

#33 . . 127 turns

#34 . . 143 turns

#35 . . 158 turns

#38 . . 224 turns

73's de Edd

COPPER WIRE TABLE . . .

As excerpted from, ye olde Radio Amateurs Handbook:

The Common enamel is highlighted, with newcomers probably having no idea of the trailing columns for Single Cotton Covered, Double Cotton Covered, Silk Covered, Double Silk Covered, etc. each conditon, upping the overall diameters.