Model 89 Cathedral - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Model 89 Cathedral (/showthread.php?tid=8400)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Model 89 Cathedral (/showthread.php?tid=8400)
RE: Model 89 Cathedral - Warren - 03-09-2014
Sounds like you have a natural ability to get SW on a Radio... Maybe you can do it to my Radio I don't get sw stations yet .
RE: Model 89 Cathedral - NostalgiaRadioTime - 03-09-2014
You might be right, Warren!
After three attempts at rewinding that tickler on the OSC coil, all with the same shortwave result, I need some clarification. More like I need to eliminate the nagging feeling I'm doing it wrong....
According to Skyscraper, It is 27 turns, clockwise from the bottom, of 34, 36 or 38 gauge wire. Lug 1 goes to the top of the coil, lug 2 to the bottom.
Now that is with the bottom of the coil... the part with the mounting arm...looking up at you? Meaning, you solder the end of the wire from the spool on to lug 2, wind clockwise (again, with the bottom of the coil where the mounting arm is facing up at you) for 27 turns, and then cut the wire from the spool and solder that end on to lug 1?
With the coil upside down, the mounting arm facing you at the 6 o'clock position, you count the lugs clockwise starting at the lug just to the left of the mounting arm?
I know I've asked this before, and I know it's basic stuff, but with the luck I'm having I just want to be absolutely clear on which direction to start winding, where to start from and where to end.
Oh and I've been using 38 gauge wire. Is that good or bad?
And I did bake it at 200 degress for a little over an hour.
Thanks!
RE: Model 89 Cathedral - Mondial - 03-10-2014
Greg, I am still wondering about one thing. Do you receive SW when the 44 RF tube is completely removed from its socket?
If you only receive the SW signal when the 44 is plugged in, then it is possible that the RF stage is oscillating and providing the local osc signal for the SW reception.
So, do you hear anything with the 44 out of the radio and the antenna connected to the 36 top cap? You should get good broadcast reception if the oscillator is working properly.
If you hear nothing but noise then the 36 osc is not working and the SW reception is most likely caused by the 44 stage (which is a separate problem).
RE: Model 89 Cathedral - skyscraper - 03-10-2014
Greg, that's correct according to my radio, and my oscillator half way works, but it may be worth swapping lugs 1 and 2 just to make sure.
I can give you the connections for the RF coil if you still need them, the section is definitely working fine on my receiver. Have you tried injecting a 260khz signal to the grids of the 44 and 36 tubes? The instructions are on the schematic at NA. If that signal gets through, then I believe the oscillator circuits are tuned, and the problem is with the feedback.
I ordered 38awg wire to rewind, since Mr. Philco said it worked for him. Would like to completely rule out that coil. Out of curiosity, what material are you using to separate the two coils?
RE: Model 89 Cathedral - Mondial - 03-10-2014
Will, the vinyl electrical tape you used between the coils might be part of your problem. Vinyl is very lossy at RF freqs and could cause enough loss to make the osc marginal.
A better choice might be teflon tape, sold in hardware stores to seal pipe threads. Teflon is very good at RF and has very low loss up into the GHz region.
Might be worth a try...
RE: Model 89 Cathedral - skyscraper - 03-10-2014
I didn't use electrical tape, I used a strip of plastic cut from a resealable bag that components come it. I think they are made of polyethylene, which has a fairly low dielectric constant.
But the teflon sounds like a good idea, and is slightly better electrically than the other plastic. I have plenty around, too. Thanks!
The only problem with the coil now is the melted plastic introduced small gaps between some of the windings. That doesn't seem very significant to me, but I've ruled out everything else in the oscillator.
RE: Model 89 Cathedral - NostalgiaRadioTime - 03-10-2014
Thanks guys. I'm at work now but I know it makes no difference if the 44 tube is out or not. Maybe the RF Coil is wrong too. Will if you have that info. That would be great.
RE: Model 89 Cathedral - skyscraper - 03-10-2014
I think the RF is ok, as Mondial said, if bypassing it makes little difference.
Here are the connections. Again, looking at the bottom, clockwise, lug 1 is after the bracket.
1. B+ line after the 5k resistor. .05uf bakelite capacitor 3615L. Primary of the 1st IF transformer.
2. Ground. Also connects to something up in the antenna coil.
3. Plate of the RF 44, pin 2.
4. Fat black wire from bandswitch
5. Fat red wire from bandswitch. Second gang of the tuning cap. Wire through the can to the 36 grid cap.
Do you by any chance have access to an oscilloscope you could probe around with?
RE: Model 89 Cathedral - NostalgiaRadioTime - 03-10-2014
Mondial: I will try taking the #44 tube out altogether tonight and see if I still get short wave. Right now, it's only in the socket and it's grid cap wire connected to the #36 tube. What's the easiest way to tell if the RF stage is oscillating, and would that indicate the SW reception is caused by the 44 stage, as you mentioned?
Skyscraper: Thanks for confirming the winding for the OSC for me. I actually cut a strip of clear plastic from a page protector and wrapped it around the coil, securing it with scotch tape before I began winding the coil. I will try injecting a 260khz signal to the grids of the 44 and 36 tubes and see if that helps. I have an RF signal generator but not an oscilloscope. Thanks, too for the RF Coil connections.
All of this is very helpful information and I appreciate you both sticking with me as I fight my way though
RE: Model 89 Cathedral - gregb - 03-10-2014
You guys keep going with this one, I have the same chassis on the bench as I type. I hope it goes a little smoother but one never knows. I have a spare chassis as well if need be.
Gregb
RE: Model 89 Cathedral - Mondial - 03-10-2014
Greg, the easiest way to check if the RF stage is oscillating is to take the 44 tube completely out. It cannot oscillate if the tube is not plugged in. Just removing the cap wire will not necessarily prevent the RF oscillation if that's what is happening. If you hear SW when the 44 tube is in, but not when its removed then most likely the RF stage is oscillating.
But that's not the main question. The real problem is why you don't hear broadcast stations when the antenna is connected to the 36 top cap and that can only be caused by the 36 and its osc circuit.
If you feed a 260 kHz IF signal into the grid cap of the 36 you should hear it well, but not into the 44 RF grid because the RF stage is not tuned to that freq and the signal will be attenuated.
RE: Model 89 Cathedral - skyscraper - 03-10-2014
I'm sorry, I meant IF, not RF. Again, the specific instructions are on nostailgia air.
RE: Model 89 Cathedral - NostalgiaRadioTime - 03-10-2014
I just came up from the basement workshop. Just like I have every night since January 17th when I received this radio. Only tonight, I came up the stairs with a smile on my face.
I took out the #44 RF tube completely and hooked the antenna grid cap wire on to the #36 tube and was still getting short wave. Only I was getting a few more short wave stations tonight.
I was all set to put in the spare OSC coil I rewound Sunday night when I thought of something Will mentioned he was thinking of trying.... reversing the Term 1 and Term 2 wires to the tickler on the OSC coil. I figured I had to unsolder them anyway, so before I unsoldered everything, I'd just reverse those two wires and see what happens. So now instead of Term 1 - to pin 4 of 36 tube and Term 2 - to resistor 10 and cap 8, Term 1 goes to resistor 10 and cap 8 and Term 2 goes to pin 4 of the 36 tube.
I left the #44 tube out, and the grid cap wire from the antenna coil hooked up to the #36 tube, plugged it in and held my breath. When the set came to life I heard music! And not church organ music. So that was a promising sign. Then I began tuning through the dial... got to AM 720, heard WGN Chicago, some 120 miles south of here. Dialed up to 780 AM, got WBBM Chicago, then AM 920 WOKY Milwaukee, 1130 AM WISN Milwaukee.... in other words all of the local stations in the correct place all across the dial!!
I then put the #44 RF tube back in, put the correct grid cap wires on the #36 and the #44 tubes and tried it again. It STILL played as good as before!! Then I turned it off once more (after letting it play at least 15 - 20 minutes) and installed the tube shields. Once more, it fired right up and played as it should across the dial.
I honestly almost cried I was so happy! I don't even think I'm going to do an alignment as the dial is right on where it should be.
So, fingers crossed, it keeps working tomorrow night when I put it back into the cabinet and (hopefully) can call the job completed.
By reversing those wires, it would seem to indicate that the tickler is wound backwards, but whereas the set is playing and working as it should, I'm not about to tilt the pinball machine and try rewinding it the opposite way.
Will, and Mondial I cannot thank you enough for your patience and your kindness and willingness to help me. You are WONDERFUL people and helped me through my most challenging restoration to date. I'm forever grateful.
RE: Model 89 Cathedral - skyscraper - 03-10-2014
Bravo Greg! I'm so glad it's finally working!
I can say about that coil, from mine and other pictures I've seen, it's definitely wound clockwise, and the top/bottom arrangement I wrote earlier is the only way mine will respond at all. But I read somewhere else that oscillator coils defy all odds of being wired correctly the first time. I see what they meant.
At any rate, sorry for the confusion with my notes, congrats again on your radio! I hope to be there in a couple days, I've been very slowly learning/working since early December... This is only my second radio, and the first (A Zenith, ironically) couldn't have gone smoother. There has been a lot to learn.
Will
RE: Model 89 Cathedral - NostalgiaRadioTime - 03-10-2014
Thanks, Will. You were a lifesaver. And no your notes weren't confusing at all... what was confusing to me was why it was getting shortwave and not broadcast band! That's why I wanted to make absolutely certain I understood you correct.
I've been collecting and restoring radios for over 30 years now and never had a challenge like this before! But I was bound and determined to win the war and this radio is about ready to wave the white flag in my direction! LOL