Hello:
Restoring a 42-380X and thus far replaced all the capacitors except one in a really difficult place to reach. Radio works ok but reception on the three tunable bands is weak at best. I have a 20' single wire antenna on it while it's on the test bench. The AM band is weak with with few stations coming in, the middle band is the weakest and requires you turn the volume way up to hear anything, and the other SW band receives some stations the stations, although, are garbled when tuned in making it near impossible to understand what is being said on the station. I think it needs to be tuned but I don't know how to tune it Your thoughts on what the problem is?
Second, ther are a series of what appears to be trimmer screws on the side of the top surface of the chassis, which seems to be for tuning purposes. Does anyone know where I can get the operation manual for this, perhaps on line and for free? Thank you for your help
God bless,
Dave B
Thank you, but there are no real operating instructions there Rider gives you the schematic and related but little or no explanation of the controls on the radio. Again, thanks.
Dave B.
Hi
You don't really need an owner's manual. They are very hard to find, and often expensive when available.
The controls are, left to right:
VOLUME BASS TREBLE TUNING
Just above these controls are nine pushbuttons.
Left to right, they are: OFF - (next five buttons are AM presets) - AM - POLICE BAND - SHORT WAVE
For dial tuning, you need to push the AM, POLICE or SW buttons (depending on which band you want to listen to).
Pushing the OFF button turns the set off. To turn the radio back on, push any of the other buttons except the OFF button.
You mentioned you had poor reception with a 20 foot longwire. Do you not have your set's loop antenna connected? The reception will be very poor without it, as it is part of the tuned circuit of the set's front end. With the loop connected, if it is operating properly, reception should be excellent.
David B Wrote:Thank you, but there are no real operating instructions there Rider gives you the schematic and related but little or no explanation of the controls on the radio. Again, thanks.
Dave B.
Radio owners manuals are almost non existent. I would guess most were lost when the sets were near new. The only reasons we have service data today. Repair tech's needed the info to do their jobs so they kept the info. Several companies like riders compiled service info and sold it. Because there was a large info base available and people willing to spend the time and money to make the service info available we have it today. The few Philco owners manuals I have seen are near useless anyway. At best the 42-380X manual may show how to set the preset tuning. I'm sure if you need to know how someone here will surely know. Looks like your radio has 4 knobs, tuning, volume, bass and treble. It has 3 bands. That is about all the useful info the manual will give you plus some safety info.
You say it performs poorly. Do all the tubes check good? Have you aligned the radio? All voltages in spec etc. etc.
Gentlemen:
Please forgive my poor choice of words, "controls" I know how they work and what they do in that I have been restoring this radio for about a month. The components I am referring to are the presets in the back and the trimmers on the top right side of the chassis.
The presets on the back, I have trimmed them and they improved their station response somewhat but not all together. But above the preset screws there are other screws, smaller in size and brass in color, what are they for and how does one reset the presets?
The trimmers on the top right side as you indicated are trimmers or compensator's. I have never tuned a radio before but have a signal generator in good operating condition. I don't know how to use the generator, I've read the manual but still do not understand it's operation and where you attach the leads to interject he signal.
Finally, the tubes generally are good with the exception of the two 41 tubes which tested out as poor or 30% and 40% respectively. Could the issue be these two tubes? Ron I did not realize the importance of it's antenna, which I have, I thought the 20' one wold be superior, I will hook it up and try again.
The one thing I would really like to accomplish is tuning it, if someone is willing to allow me to call them I'll call them and invest the time where perhaps you can talk me through the process, I have a military SG 85C/URM-25D signal generator. Thanks again, I appreciate all your help
If your 41 tubes aren't very good, it would definitely reduce the volume, and it should have the same effect on every station.
If you suspect that weak signals are due to alignment, I'd try to align the IF cans first, before touching the trimmers and/or padders that are grouped on the right side of the chassis. Your IF tuning is probably way off after recapping, especially if you replaced the mica caps inside the cans. Use AM tuning for this, not one of the push button station selectors. Be sure to connect the signal generator through a cap (.1 uf, I think) to keep from putting the generator plate voltage into the antenna. You can do a rough "by ear" adjustment without the signal generator, but be sure to adjust the cans in the order 34, 31, and then 29, and then touch up with the signal generator when you are satisfied that all the tubes, components, and wiring are right. Your "by ear" adjustment can tell you whether alignment might be responsible for low volume, but you'll probably set the IF way off.
The two rows of controls on the back are both to tune the push buttons. The upper row in back are capacitors to tune in the antenna for each push button selection, and the lower row are tunable inductors to tune the oscillator for each station. Select a push button, and use the oscillator control for that button first to bring the station in, then try the antenna capacitor right above it, then go back and forth until it is as good as it gets. It can be touchy. It would be best to adjust push-buttons with the radio in the cabinet using the loop antenna. There might be an easier way, but that is how I do it.
The Riders page on Nostalgia air shows the locations of the IF compensators on top of the IF cans, and the order in which to adjust them. The copies aren't very good, so I'll make a plug for Chuck Schwark's Philco packages, which are excellent and reasonably priced.
http://www.philcorepairbench.com/schematics.htm Chuck's package will probably also have more thorough and specific push button tuning instructions.
I use about a 20 foot wire antenna for my workbench. It works quite well for AM in my area, even though my workbench is in the basement. The loop in the cabinet is better. Short wave with the 20 foot wire is marginal, but good enough to tell me if the band works.
You could also grab the pdf of the book
Elements of Radio Servicing at this site:
http://www.antiqueradios.com/archive.shtml and read the chapter on alignment. It might also help if you read the chapter on oscillators to get familiar with the function of trimmers and padders. I lived with this book for about a month before I ever dug into a radio, but I'm still not very experienced at alignment.
To adjust the IF can compensators you would inject the signal though a cap into terminal 4 of the antenna terminal strip in the back of the radio. Terminal 1 goes to the output xformer, so use that one to connect a high impedance meter (also through a capacitor) to measure signal strength while you move the compensators. (You can also listen to the speaker volume.) Underneath the parts list, the Riders page gives a table and some notes to explain all of this, but I'd still advise reading the chapter on alignment in Elements of Radio Servicing before tackling it.
Edited to add:
I went back and read your original questions about the functions of the compensator adjustments. As near as I can tell, they are as follows:
29A, 29B, 31A, and 34A on the IF cans are to adjust the resonance of the interstage transformers to exactly the intermediate frequency of 455 KHz. If any one of these is off, it will reduce your sensitivity by filtering out the intermediate frequency.
4A, 4B are to tune the antenna for the broadcast band and shortwave band, respectively.
4, 4C, 4D, and 4E are to adjust the tracking of the oscillator for the various bands so that the dial pointer will show the right frequency at every point. If these are out of adjustment, you can adjust the pointer to one station's frequency on the dial, but it will point to the wrong frequencies as you track above and below the one station you set.
Except for the IF cans, these adjustments should be made with the chassis in the cabinet and the loop antenna connected, injecting the signal generator frequency indirectly by making a loop of a few turns of wire and setting it up close to the radio's loop antenna. Then follow the instructions in the Rider's manual in the table and the notes under it. Elements of Radio Servicing Explains this loop antenna connection in Chapter 22, page 415.
Edited to add: Antique Electronic Supply has 41 tubes ST style 50% off until September 30. I'd replace those bad ones you have ASAP.
Gentlemen:
Thank you for your insightful information. Upon completing the sermon this week I will undertake these suggestions. If you know of any one familiar with the SG 85C/URM-25D signal generator and it's use please let me know. I have a working one but do not know how to use it. Again, thanks.
God bless,
Dave B
Thank you again for the information. As to adjusting the cans, 34,31 and 29, do you use a plastic or metal screw driver due to capacitance? On 29 there is both A and B do you adjust both or one and in which order? I have never tuned a radio so in adjust the cans do you turn the screws until the signal sounds the best or do you turn the adjustments in only one direction. I copied Elements "Alignment" chapter and will read same. Thank you in advance for your answers.
Dave
I try to use plastic screwdrivers whenever I can, but I find they are often not strong enough. One of my adjustment tools is a plastic handle with a tiny metal insert to make the screwdriver blade, but it doesn't fit everything. Metal screwdrivers seem to work OK most of the time...at least I don't get a big change in adjustment when I take the screwdriver off the adjusting screw, which is what I would expect. If you can move compensators with plastic, use that.
I turn the compensator screw back and forth until I get the best signal. I use a VTVM through a capacitor to measure the best output. My VTVM isn't working quite right, so if in doubt I listen for the highest output and call that good, even if the VTVM shows off-peak. On some of the tracking adjustments you want to "rock" the adjustment (explained in "Elements" and in the Philco instructions, I think) but you can still use the sound or the meter to judge the peak.
John:
Once again I greatly appreciate your response. As to compensator 29, do I adjust both A and B or one or the other, and does it make any difference as to the order? Thanks.
Dave
Be sure to follow the Philco factory alignment instructions for this set. A "generic" alignment may not produce the results you need for certain models.
Chuck
Dave,
Re: 29A and 29B, I can only refer to the John Rider alignment instructions that are on Nostalgia Air. Those instructions say to adjust 29A and then 29B in that order. I assume you have downloaded these free pages from Nostalgia air:
http://www.nostalgiaair.org/PagesByModel...013533.pdf
It is very hard to read, but it looks like 29A is an adjustable inductor in the transformer # 29, and 29B is an adjustable capacitor on the secondary side. As Chuck mentioned, the Philco factory alignment instructions might differ. I don't have access to those instructions for this radio.
Assuming compensators 34A, 31A, 29A, and 29B are adjusted properly in that order, with a signal generator, then you should get the best sensitivity with any given antenna. If your sensitivity is still not good, try the loop antenna in the cabinet, and then I'd suspect a tube or other component in the chassis.
Did you replace the 41 tubes that you already think are bad? The AES tube sale goes through Sept. 30. I might buy a couple of 41s myself.
John:
Replaced both 41s which I purchased from AES, thank you. They had little or no affect on radios performance. Thank you for new info I figured I would hook up 20' the antenna to the set and trim it by ear as you suggested. should i tune it to a week or good station to try this and should it be one of the tunable stations or preset stations. Again, thanks.
