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Philco 38-2 Automatic Tuning - Printable Version

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Philco 38-2 Automatic Tuning - dconant - 11-03-2024

Hello, I am having trouble getting my automatic tuning to stay unmuted. If I play with the tuning handle I can get it to unmute but as soon as I try to tune in a station it mutes again and stays that way until I play with the handle again. I believe the problem is with the movable contact. Ron Ramirez talked about this back in a 2016 post. There was a picture there but it is no longer showing. Bob Andersen also shows some pictures but I don't see a slot. I have mine set exactly like Bob's last picture. Can someone describe exactly where that contact goes and maybe how it works. See https://philcoradio.com/phorum/showthread.php?tid=13848&page=2&highlight=automatic+tuning for Bob's pictures. My Philco schematic says the automatic tuning is the same one as the 37-10.

Thank you,
Dan

RE: Philco 38-2 Automatic Tuning - dconant - 11-03-2024

I figure out the muting from another picture that helped. Now I need to know how the automatic tuning works. When I push the crank on the desired station the radio mutes and then I let go the radio unmutes but it is still on the same station it was prior. I have done this with magnetic tuning in and out.

RE: Philco 38-2 Automatic Tuning - morzh - 11-03-2024

When you push the lever, you are supposed to rotate the disk to the desired station.
Then the magnetic tuning will acquire the station and lock to it.

It is a form of AFC (auto freq. ctl).
I works as PLL (Phase locked loop), where the two wfrequencies are compared, the difference is converted by the discriminator into the positive or negative pulses, which then are smoothed (integrated) by a filter (a capacitor), and the voltage developed on this capacitor controls the frequency of the VCO (a Voltage controlled oscillator), which intern compensates for the station frequency deviation, or, if needed, for the inaccuracy of the positioning of the tuning cap (as this mechanism has an error).

RE: Philco 38-2 Automatic Tuning - dconant - 11-04-2024

I'll have to see how this works out once I get my dial back from Radio Daze. I sent mine in for them to reproduce. I ordered some other dials too so that is slowing the return of my original and new one which is now available on their web site.

So the automatic part of this is you do some manual work to get it close and let go and the station pops in. Do you use the crank to turn the dial or do you hold the crank in with one hand and turn the dial with the other?

RE: Philco 38-2 Automatic Tuning - radiorich - 11-04-2024

Hello Dconant,
In my collection I have a model 38-7T which Philco called their famous "Cone-Centric" dial mechanism.
I really like the look of your console .

Sincerely Richard

RE: Philco 38-2 Automatic Tuning - morzh - 11-04-2024

You press the lever (crank) and you rotate the dial into the desired position.
Also, while pressed, the contact that it presses on will mute the radio.

RE: Philco 38-2 Automatic Tuning - RodB - 11-04-2024

Does it wash your windows? Then it would be useful and worth fixing. Music and window washing.

RE: Philco 38-2 Automatic Tuning - morzh - 11-04-2024

I found out, I never use it in my 37-116 and 38-690. I made sure it works, but this was it: I always hand tune.

RE: Philco 38-2 Automatic Tuning - dconant - 11-04-2024

Seems more like a selling point to me. I too have have a Philco with the Cone-Centric tuning. Hopefully I will get the chassis back in the cabinet soon and then I will post some pictures. Cabinet needed stripping but it is finished now. I didn't use stripper I scrapped the finish off with a small paint scrapper which to me is a lot less messy. Worked very well.

RE: Philco 38-2 Automatic Tuning - morzh - 11-04-2024

Well, you could take a look at most features of those radios, and other than some very few of them, they all are selling points.
From the inclined front panel to the tuning indicator.

RE: Philco 38-2 Automatic Tuning - radiorich - 11-04-2024

hello dconant ,
my set is the tabletop one and it also needs refinished someone put plant or something on top and the finish is coming off .
I hate cabinet refinishing my thing is chassis restorations !

Sincerely Richard

RE: Philco 38-2 Automatic Tuning - dconant - 11-04-2024

Hi Richard, I enjoy it to some extent. I do that type of work out in barn (modern) during the summer on nice days when I like. This way it keeps the mess out of the house. I also do the chassis cleanup in the summer which can get quite dusty. I pretty much remove everything I can so I can get in all the nooks and crannies and then do a clear coat. I save the electronics for the winter months. It all keeps me busy now that I am retired.

Dan

RE: Philco 38-2 Automatic Tuning - rfeenstra - 11-05-2024

I have 2 36-116's with magnetic tuning and it works well. Once tuned, it does not drift. Never have to retune when I turn the radio on. , even after a month of not being used.

RE: Philco 38-2 Automatic Tuning - poulsbobill - 11-05-2024

Same with my 37-116. I love it

Bill

RE: Philco 38-2 Automatic Tuning - dconant - 11-05-2024

Looks like my 38-2 is in trouble. The set started to turn itself off. I thought maybe the switch needed cleaning so I did that and it played for quite a while then I turned it off and let it set for a bit. Did not turn back on. I noticed the rectifier tube was glowing so not a switch problem. I did some checking and found I have 5 volts and 700 volts ac but no 6 volts. I have about 5 ohms on pins 2 and 7 of the other tubes with tubes in. Probably when it draws current the connection opens up. Guess I need to open up the transformer and do a little poking around. Transformer does not get hot. Bummer.