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City: Sneedville, TN
Actually, the coil form I used was a plain old toilet paper tube, not PVC, although I figure PVC would work if the inside diameter were enough. Also, when doing the alignment, don't worry about the tone at which the RF is modulated, as long as it is easy to hear. My sig gen modulates at about 1000 CPS. The important frequency is the RF one, that needs to be as exact as possible. I double check mine with a small digital readout shortwave radio I have. For IF, I set the radio at double the IF frequency, for 455 KC, I set the radio to 910 KC, for 460 KC it would be 920 KC. I then tune my sig gen until I hear the max signal on the radio, then I know I am as close as I needs to be. For the AM band, I just use the exact frequency to double check my sig gen, the same with short wave bands. Have you tested the mixer oscillator tube in your set yet? That might be the problem. One piece of equipment you really need to invest in is a tube tester. They are more expensive than they were a few years ago, but you can still find one which works for less than $200. I advise replacing any electrolytic or paper condensers you find in it, but that should be about all it will need. Some will have a tube of their own inside and it may need to be replaced. They are usually not too difficult to work on, although they can be cramped inside. Be sure to look at it carefully. You will want one which tests the old type 4, 5, 6, and 7 pin tubes, as well as locktal and octal tubes. Many which test all these will also test 7 pin miniature tubes, although their tube charts may not list all the 7 pin tubes since these predate many of them.
(This post was last modified: 02-08-2021, 01:42 PM by mikethedruid.
Edit Reason: add info.
)
Posts: 21
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City: La Baie
State, Province, Country: Québec
I stand corrected - it was PVC insulated wire. I was multitasking when I wrote my response - when am I going to finally learn that I can't multitask?
Posts: 21
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Joined: Feb 2021
City: La Baie
State, Province, Country: Québec
Radioroslyn - I swapped out the 78 tube and there was SOME improvement. I can pass a 460 KC cycle through the set, but it is VERY weak. The tone is not clear, and has much static. I thought that I might have better luck by connecting to the 6A7 cap, as per the Rider instructions. There was NO tone after that and much electronic buzzing, even with the volume reduced. The tube tests okay. Any input would be appreciated.
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City: Roslyn Pa
>I can pass a 460 KC cycle through the set, but it is VERY weak.
So when you adjust the the previous mentioned trimmers can you get to signal up to a reasonable level??
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: 21
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City: La Baie
State, Province, Country: Québec
No - it remains very weak. Yes, the trimmers have a limited effect on it, but it is not what it should be.
Additionally, I tried locating a defective part/stage by using the signal tracing method: Using 460KC and the axial lead of a .01 cap as a probe, I cannot pass a signal from the grid of the 78 tube to the speaker. I can hear the click when the probe touches it, but no tone. When the probe touches the grid of the 75 tube, I get LOUD buzzing.
This set really has me stymied. I can pass various frequencies at the antenna post, rotate the tuning cap, and hear the tones in the speaker - but I cannot pass a decent 460KC.
Posts: 21
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Joined: Feb 2021
City: La Baie
State, Province, Country: Québec
Mikethedruid - many thanks for your advice. Yes, I have a tube tester, and before I do any work on a set, I test the tubes. This 60B really has me stymied. I've been VERY careful with each step i.e. re-stuffing the condenser blocks, replacing out of tolerance resisters, replacing decrepit wiring etc. and something just isn't right. I've tried to locate a defective part/stage with the signal tracing method to no avail. Obviously, I have missed something or done something wrong, but I've never experienced the symptoms that this set is giving. I'm stubborn as a mule, and I'm not going to give up, but I must admit to feeling frustrated.
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City: La Baie
State, Province, Country: Québec
Partial success: I can now pass a 460 KC Cycle. The problem: An intermittent short in one of the signal generator leads!!! Do I feel stupid? Yep! Is my face beet red? Definitely!!! The IF's are now aligned, but still can't receive any stations - One baby step at a time!
Posts: 7,248
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Joined: Dec 2009
City: Roslyn Pa
Next steps are to check the voltage @ the 6A7 tube mostly the plate, screens and cathode. If all seem reasonable check to see if the osc (lo) is operating. This can be done by setting the dial on the Philco @ 100 (1000KC or 1MC) and listen in with another receiver with the ant wire wrapped around the 6A7@ 1460kc or thereabouts. I'd give it about 50kc +/-. If you don't hear a loud hiss good chance the lo isn't working. Time to have a look at the osc coil primary. Look for small green dot(s) resistance above 20 or 30 ohms or no resistance (open). Oh and just for grins connect the ohmmeter across the osc section of the tuning cap with it complete open. Should read and a few ohms turn the dial and till it's closed it should read the same. If it drops you've got a bent plate that's shorting the cap out. GL
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: 21
Threads: 1
Joined: Feb 2021
City: La Baie
State, Province, Country: Québec
...still waiting for a dial, before I can attempt the last suggestion i.e. using a 2nd set to ascertain if the oscillator is working. I did do the other tests: Voltages on the 6A7 are fine. The oscillator primary shows continuity and the resistance for the 18 turns of wire is .3 ohms. I checked the oscillator section of the variable tuning cap: With one clip on the wired output lug, and the other probe on the stator, the resistance read .9 ohms throughout the entire range of motion. I did receive one station, last night. It was VERY faint, but I could make out the words that were spoken. It seemed to be near the high end of the BC range, but without the phenolic dial, I don't know the frequency.
(This post was last modified: 02-16-2021, 11:40 AM by LDel.)
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Joined: Dec 2016
City: portland, OR
shouldn't the resistance between the wired output lug and the stator of the oscillator section of the variable tuning cap be 0?
any chance you removed but didn't reconnect the braided ground strap from the tuning cap support to the chassis? i speak from experience.
the station you did receive, was the frequency a multiple of the IF = 460? like 1380KC. that would indicate no signal from the oscillator to the 6A7. i speak from experience.
Posts: 21
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City: La Baie
State, Province, Country: Québec
The braided ground strap is connected - I'm sure of that.
As for the resistance measurement, between the wired output lug and the stator being .9 ohm: I don't know what it should be. Should it be 0 ohms?
As for the faint station I received, I am still working without a dial - but you did address something that is going on in my mind: Was that station simply a multiple of the 460KC? I think it's quite possible. When I get a dial, I'm going to try the experiment, proposed by Radioroslyn.
If this set isn't oscillating, and I don't think it is, I don't know what I'm going to do. The oscillator transformer windings have continuity, and I have been very meticulous in replacing out of tolerance resistors, and re-stuffing the condenser blocks, as well as the condenser bank.
The only wiring change that I have made was with the on/off switch and volume control. The original was a rheostat, and the connected switch was beyond repair. I replaced it with a switch/potentiometer - grounded to condenser block#7. The pot is 1 meg, which is larger than I wanted, but that change should not be creating problems with the oscillator.
I'll entertain any/all suggestions.
Posts: 7,248
Threads: 266
Joined: Dec 2009
City: Roslyn Pa
>shouldn't the resistance between the wired output lug and the stator of the oscillator section of the variable tuning cap be 0?
No. The stator (the stationary part) is connected to the frequency determining section of the osc coil. So what ever it's resistance is it will be also. Generally abt 10-20ohms for the bcb lower for the swbs.
Still haven't proven that the osc is working. With out it your still dead in the water. It this point the resistance measurements don't mean any thing we need to see or hear a signal from the osc the start at the bottom of the dial 1010 (550kc on the dial) and at the top 2260kc (1700kc on the dial).
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: 21
Threads: 1
Joined: Feb 2021
City: La Baie
State, Province, Country: Québec
Okay - even though I don't have a dial, for accuracy, I'll give things a try.
As always - thanks!
Posts: 21
Threads: 1
Joined: Feb 2021
City: La Baie
State, Province, Country: Québec
Radioroslyn: I did the experiment that you suggested - Yes, the Philco is oscillating - and I now have a replacement phenolic dial to complete the alignment.
I think that I have discovered the problem: When I moved from the States to Saguenay Québec in 2013, I unpacked all of my radios and verified that they worked. They were then placed on shelves and only used if a visitor indicated that they would like to hear a particular radio playing. The last time that happened was 5 years ago. During the past 5 years, unbeknownst to me, almost every AM station in the province has converted to FM, or closed up shop. There remain 4-5 very low powered stations, 6-8 hours away, used mostly for religious services, but that's it.
I do not have an exterior antenna - and zoning will not permit one. None of my radios can pull in a station, until the night time hours, and even then, the stations are faint. I am in a virtual AM dead zone. The Philco 60B may very well be working correctly, and I may have been spinning my wheels to no avail. I have purchased an AM transmitter, off Ebay. When it arrives, I'll connect to my stereo, and ascertain if I can receive its signal on the Philco. Other than that, I do not know what else to do. (No, I don't like the idea of adding bluetooth - I like to keep the sets original.). I'll let you know, if the transmitter is successful. If it isn't, I'll be looking to you for more suggestions. Please know that I am VERY appreciative of your responses.
I listen to old 78 rpm records, watch old black and white movies, and tune into online vintage radio programs. The lack of high-fidelity, afforded by AM radio has never been a bother for me. It saddens me to see the AM system vanish into obscurity.
(This post was last modified: 02-24-2021, 03:35 PM by LDel.)
Posts: 897
Threads: 37
Joined: Feb 2015
City: Roseville, MN
You might want to try some of the antenna alternatives discussed here on the Phorum or a "Mini Whip" sold online.
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