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A Philco 38-690 Restoration - Printable Version

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RE: A Philco 38-690 Restoration - WyTex - 06-02-2018

+1!!

 Thanks for documenting your dedicated effort.

Paul

RE: A Philco 38-690 Restoration - Ed Locker - 06-02-2018

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RE: A Philco 38-690 Restoration - Electrothaumaturgist - 06-02-2018

KUDOS, Ron!!! Beerchug It's always wonderful when they come roaring back to life!  I salute you sir! Salute

RE: A Philco 38-690 Restoration - Kenradio - 06-02-2018

Great job Ron! Icon_thumbup Icon_thumbup Icon_thumbup Icon_thumbup

RE: A Philco 38-690 Restoration - Ron Ramirez - 06-02-2018

Thanks, guys! Icon_biggrin

June 2 (evening).

I had intended to align this set this afternoon or evening, but life got in the way - three trips to the local yard waste dump to haul off tree branches, then mowing the yard. I'm very tired now.

So this evening, I set out to reassemble the tuner's Automatic Tuning unit.

[Image: http://www.philcoradio.com/images/phorum/38-690/38690_092.jpg]

It now has a brand new dial scale from Radio Daze.

Now allow me to point out the pros and cons of the Radio Daze dial scale.

Pros:
Very, very faithful reproduction - looks just like a brand new Philco dial scale. The graphics are perfect. Gone are the days when Radio Daze printed dial scales on paper and then laminated them. This is a genuine silkscreened dial scale.

Cons:
The inner opening isn't quite large enough. I had to sand, then scrape with a knife, then sand some more to make the opening large enough to fit on the "hub" of the tuning mechanism.
There are no slots cut into the opening, either. The original scale had a very small slot to fit onto an index on the "hub". Also, there was another, larger slot which is used to fasten the dial scale to the back of the piece which holds the call letter tabs. A tiny screw is used to fasten the scale to this piece.
I carefully cut both slots with my handy-dandy Ryobi "Dremel" tool. It worked out quite well. Believe me, I was extremely careful both in enlarging the inner opening of the dial scale and in cutting the needed slots!

Not sure if this is a pro or a con:
The new scale is twice as thick as the original. It does result in a stiffer, less flexible dial scale, which may (or may not) be a good thing depending upon your point of view.

In spite of all that, I am still happy with the new scale and I would buy another. It's still better than having no scale at all, or a broken or badly discolored one.

[Image: http://www.philcoradio.com/images/phorum/38-690/38690_093.jpg]

Oh, and I could not find the tuning knobs, or the band switch knob. Icon_eek I'm blaming our cat, Виктор, for taking them. I did catch him today with a couple knobs he had knocked off the bench and was using as toys. Fortunately...Sam had answered my request for tube shields by giving a box of misc. parts to me at Kutztown, which not only included tube shields but also...the very knobs I needed to replace the missing knobs! Bless you, Sam! Icon_angel

Tomorrow: A thorough alignment, and then this gets moved off the bench to make way for the next project - my RCA T7-5.

RE: A Philco 38-690 Restoration - EdHolland - 06-03-2018

Great work Ron!

It is very interesting to see what is needed to do a proper job on some of the most challenging designs.

RE: A Philco 38-690 Restoration - morzh - 06-03-2018

Them Russian cats. One needs to keep a close eye on them. Even their "Meow" sounds like "мяу".

As for the Daze, I used their dial for 37-116. Same exact thing, no notch and the diameter of the hub about 1mm too small. Had to grind it off. Though the quality was not as good - there were discrepancies in the silkscreen with the original.

RE: A Philco 38-690 Restoration - Ron Ramirez - 06-03-2018

June 3.

Alignment time! All five bands, as well as the Magnetic Tuning, are now aligned.

It's been several years since I worked on one of these 1938 Code 125 RF units, and I had forgotten the fact that while the adjustments are relatively few compared to the 1937 RF units (and the 1938 Code 121 models), this also means that it is usually not possible to achieve perfect tracking on all bands.

This is indeed the case with this 38-690. 580 kc is coming in just above 590; 1550, at 1530; 990, at 1005; and 660, at 675. It's the best I can do given the limitations of the adjustments and age of components - remember, this radio is 80 years old and I did not replace any mica capacitors in this RF unit (not that that would have made much of a difference).

Here's a demo showing that the radio is working on all five bands. I basically skipped over bands 3 and 4 but you can hear the typical noise on these, proving that these bands are not "dead".

[Video: https://youtu.be/2Uo65-rhGuU]

It still produces a slight static or "sizzle" noise at first power on which sounds like it is coming from the RF unit, but it now stops almost immediately. I'll probably clean the band switch one more time - I did hit it with an evaporating contact cleaner yesteday, followed by compressed air in a can last night. Nevertheless, I consider this project finished. After 3+ months, I am not inclined to go any further with this one.

So that is it for this thread. Many thanks to Sam and Mike Schwartzman for the assists (tube shields, knobs, and the third and final RF unit, respectively), to those who posted words of encouragement along the way, and to all of you for reading along. Icon_smile

RE: A Philco 38-690 Restoration - sam - 06-03-2018

sound and looks great ron   Icon_clap Icon_clap Icon_clap Icon_thumbup

RE: A Philco 38-690 Restoration - Ron Ramirez - 06-03-2018

Thanks Sam Icon_biggrin

One more video and I'm finished with this subject...

In this video I power up the set, let it warm up, tune in my home transmitter, then use the Automatic Tuning feature to automatically tune to a few preset stations. There is nothing on those frequencies here, but this video will demonstrate the following:

1. There is no longer any static/sizzle on initial power-up, so the band switch is now as clean as it will get; and
2. The muting feature of Automatic Tuning is working properly.

I shot this video a few minutes ago, so the set had plenty of time to cool off between this morning's alignment and a little while ago.

[Video: https://youtu.be/0UG6p_4e8wY]

That's it - on to my RCA T7-5!

RE: A Philco 38-690 Restoration - NostalgiaRadioTime - 06-03-2018

Outstanding work, Ron. Really enjoyed this thread. This set will certainly be the centerpiece in your home. Congratulations! Icon_clap

RE: A Philco 38-690 Restoration - tbone - 06-03-2018

Great job on this project Ron. Icon_thumbup It was great following along as you went.

RE: A Philco 38-690 Restoration - Kenneth F. Besso Jr. - 06-04-2018

WOW,,,,Another fantastic job, ( workmanship ),,,with a tuff little unit,,,,,,,NICE,,,Mr. RON,,,,