Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

Philco 42-380X Reception problems
#7

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.

John Honeycutt


Messages In This Thread
Philco 42-380X Reception problems - by David B - 09-14-2008, 09:51 AM
Re: Philco 42-380X Reception problems - by Raleigh - 09-16-2008, 10:57 AM



Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
Try looking at this site the book mark is for a old generator that I was given. David    https://radionerds.com/index.ph...David — 08:36 PM
Plug Voltages Needed For A 1943 CRV-20130 Power Supply
Hello Everyone, I am looking for voltage identification for all the pin positions on the socket of a CRV-20130 power su...Tonym4704 — 08:16 PM
Philco P45-6365 Universal Transformer Instruction Manual
Can anyone guide me to where this may be found?GRG — 03:00 PM
54C Complete Teardown/Rebuild
I don't think that I have encountered a 12Z3 before, curious how it uses one of those but includes a #43, which is a 25 ...Arran — 02:17 PM
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM

[-]
Who's Online
There are currently no members online.

>