philco: World's Fair; 39-116RX (39-116)
Hello dear Radio Collectors. I am looking for a copy of the Rider's information for this radio. In particular I need the parts list and the chassis parts view. The copy I have is of poor quality and the small numbers blur together. I'd be happy to do the scanning and add it to the model if someone has a hardcopy they could send me. Thanks!
I scanned and uploaded the remaining pages of Philco Service Bulletin #310, which is the original Philco source for the information in Rider. Take a look and see if it has the information you need.
If you still prefer Rider, I also have that in hardcopy and can scan it and upload it.
Good luck with this radio and its Mystery Control. This was a very high end model for Philco in 1939, so it should be a very impressive set!
Bless you, Thomas. My poor tired eyeballs thank you. Now I can finally see those blasted tiny part numbers. The main interest of this radio for me is the fact that it was the very first use of wireless remote control in the world for consumer electronics.
So far, my work is progressing remarkably well on this radio. I have a thread going on it on antiqueradios.com. After replacing just three filter capacitors, the radio receiver works well. I have the Mystery Control transmitter working now too. All I need is one more electrolytic and I think I'll have the remote receiver running too. Just to read it into the record, for the benefit of anyone else with one of these, here is what I discovered about how the Mystery Control automatic station changer works (taken from my ARF thread). As far as I know, there are no other descriptions on the web of how this mechanism operates. It's really quite fascinating:
OK, after playing with it for a while, and cleaning the contacts on the station changing switch, and thanks to the invaluable assistance provided by some kind ARF members, here is my definitive version of how this whole thing works:
1 .The station selecting switch (SSS) is a flat rotary 3P8T switch located under the chassis. It simultaneously sets the coil, capacitor, and station pilot light for one of 8 different stations. In the beginning, the SSS can be in any one of 8 different positions corresponding to the last station tuned - it doesn't matter which one. In the figure below, the switch is set to station 3:
2. Receiving the first pulse from the Mystery Control causes the holding relay to engage (and it must remain engaged during steps 2-5 below). The first pulse also causes the stepping relay to advance its ratchet one position. However at this point it does not yet cause the SSS to move. (You are still tuned to the last station you were listening to).
3. Pulses no. 2 and 3: these are for volume control. They also do not move the SSS.
4. When the fourth pulse (if any) is received, the pawl on the SSS (secondary) ratchet is released, causing the spring on the secondary ratchet to quickly rotate the SSS back to station 1. This happens very fast - it literally snaps back, in less time than the inter-pulse gap. (In my radio, I had to clean and lube the SSS and exercise it a few times before this would happen. The spring is strong enough, but not that strong).
5. If any further pulses are received, each one will cause the SSS to advance one more position. The SSS has already been pulled back to station one in step 4 above. If no further pulses are received, it means you intended to tune station 1 and we go right to step 6. Otherwise, the 5th pulse causes it to advance one position and selects station 2, the 6th pulse selects station 3, etc. up to the 11th pulse which selects station 8.
6. When no more pulses are received, the holding relay drops out and the SSS stays where ever it was when it got the last pulse. The cycle is complete.
7. The next time you twist the dial on the Mystery Control, the entire process starts over again with step 1.
here is just a picture from an old Electronics magazine. It can help to create the proper atmosphere when you operate your radio from the armchair. After all, you know more than Mr. Skinner about the operation of the mistery control.
Hi Emilio - yes, that's a great picture. It also shows that although this radio has a "39-" model designator, it did exist at least as far back as July 1938. Although some radios had wired remote control at this time, this was the very first use of a wireless remote. This was Philco's top of the line radio for 1939 (along with the -PCX which was the same radio but included a phonograph too). It must have been quite the luxury item back then.
Philco was apparently very concerned about interference causing unwanted operation of the radio. All five tubes in the remote receiver are shielded, there is a 0.05 uF capacitor across the AC line molded right into the plug, and four of the paper capacitors in the remote receiver section under the chassis have their own separate metal cover.
This very interesting example shows again how important it is that we use the true market introduction and not the prefix or some other marketing goal. Not all manufacturers followed this way and openly wrote about the 1938 model - in the same case ...
We seem to be an exception with the true naming of the market introduction but I don't mind to be different if it is better or truer. We have to accept and acknowledge that at least after the 20ies model planning (new tubes jsut for testing?), design, provisional construction and testing, crating tools for production, set up production line, production and marketing etc. were seasonal, not bound on the calender year: The introduction of a new model was intended to sell at least before christmas. Often many weeks before - even some already in Summer, very seldom in Spring for special reasons. Therefore we have the two fields for the year: from/to.
When I read your very clear description of the operation of the Mystery control, I sent the link to this thread to a couple of friens who own Philco Mystery remote control radios. Gary Norman emailed back this short note describing his experience operating and repairing the Mystery remote system.
Thanks for the very good post,
Date: Fri, 03 Jul 2009 16:08:05 -0400
To: Joe Sousa, Ron Roscoe
From: Gary E Norman
Subject: Re: philco: World's Fair; 39-116RX (39-116)
Thanks very much for the kind words, Joe. And thank you also for the input from Gary. The SSS spring is indeed critical. One also observes that to prolong the life of this spring, it is best to leave the radio set to Station1 if it's going to be off for any period of time. This leaves the spring in its least extended position.
There are indeed several screw adjustments one can make to the system. They can be found by the drops of red lacquer applied by the factory to hold them in place and to identify any tinkering.
Because this thread has generated a bit of attention, I have decided to expand my description of the operation of the mechanism. It's really fascinating, even if you don't own one of these radios. Today I added a picture of the station selecting switch. I'll be adding more as I have the time and after I actually get the system running and understand it better myself.
Hello Michelle and Philco Radiophiles,
Yesterday, I got to see Ron Roscoe's Philco 39-116 receiver working with the Mystery remote after the 2A4G Thyratron was replaced. The original Thyratron was defective and was constantly on.
I think we also figured out the function of the 6ZY5 rectifier in the AGC circuit.
One significant difference between this 6YZ5 rectifier circuit and the diode connected 6J5 circuit, is the value of the coupling cap, which is 550pF for the 6J5 and 0.02uF driving the plates of the 6ZY5.
When the 6ZY5 is pulled out, the remote pulse counting becomes erratic, and the RF burst driving the grid has an envelope that shows a large overshoot, and rapidly decays to the AGC controlled envelope amplitude. The job of the 6ZY5 is to clip the start of the pulses until AGC action takes over with complementary time constants. This test was done at close range, to get AGC action.
The remote reception seemed unaffected when the 6J5 AGC detector was pulled out. Again, checked at close range.
(By the way, Ron's house was built over a concrete slab with steel reinforcement. He may get more range by lifting the receiver loop off the floor. This may also detune the loop. He demonstrated to me a range of about 5m over the concrete floor. The remote control receiving loop lays horizontal occuppying the entire bottom of the cabinet, and sits no more than 6"=15cm above the floor)
As I look at the time constants for the two AGC circuits, it becomes apparent that a pulse rate bandpass filter action is bounded between the high cut of the 6YZ5 with a 15ms time constant (10Hz) set by 104 and 106, and the low cut of the 6J5 with a 75ms time constant (2Hz) set by 113 114.
Ron's radio is the Philco 39-116, but if you look at the Philco 39-55, there is no 6J5, and the two detector functions of conventional AGC and suppression of AGC action overshoot, are performed by each plate of the 6YZ5.
The 6J5 in the 39-116 represents a clear case of tube count inflation over the equally effective 39-55 design.
The 1Meg resistor 107 in the 39-116, and 86 in the 39-55, going back to the speaker voice coil can also add any negative noise spikes present at the coil to increase AGC action in the Mystery control receiver. The phase of the speaker connection must be correct for the burst envelope to be represented by a negative spike.
The Mystery remote control signal remains as an RF burst right up to the Thyratron grid. This grid is normally kept off with approximately 20V p-p AC that is out of phase with the plate. When the plate is positive, the grid is negative. The RC network at the grid, also forms a grid leak circuit that converts the 20Vp-p AC from the thirt tap at the filament transformer, into a 0 to -20V swing. When the RF burst is applied, it is added in series with this voltage by RF transformer 103 in the 39-116 and 74 in the 39-55, and the positive peaks of the RF burst fire the thyratron grid.
Thanks very much Joe for that excellent and illuminating analysis of the very interesting Mystery Control receiver section of the 39-116. In particular, I am pleased to see the time constants you came up with since they correlate well with the pulse lengths I measured empirically using my microprocessor based Mystery Control pulser emulator (see my article on "Characteriszation of the Mystery Control") at http://www.radiomuseum.org/forum/philco_characterization_of_the_philco_mystery_control.html. And if someone could move that aritcle to the Mystery Control model page, that would be appreciated. I really thought I had posted it from there but I see now that it does not seem to be there anymore.
Anyway, I have now completed my restoration of this radio. Philco specifies a range of 25 feet (7.6 m.) for the remote control. I am easily getting more than that with the sensitivity control turned up about 3/4 of full scale. In fact, I can activate the radio reliably from anywhere in my two-story wood frame house. I altered the factory receiver alignment procedure a little. Philco suggests adjusting the receiver for "peak brillliance" of the flashes of the 2A4G Thyratron. This sounds good but in practice is wholy unsatisfactory. There is not much brightness difference as one adjusts the coils and it is impossible to find reliable peaks this way.
Instead, I connected a scope probe to the C104-C105 junction and peaked the signal found there with the Mystery Control in continuous mode (finger-stop depressed) and placed near the receiver using just a short length of wire as an antenna. There is no need to use the set's built-in "secondary inductor" for this procedure. Peak L103 first, then L115, and lastly L119.
I have made some short movies available that illustrate the mechanical components in action, including the station switch, the relays and the Mystery Control itself. You can find it at http://radiodemo.110mb.com.
There are six short movies there as mpeg files, each under a minute long. Due to complaints about the site not working with Internet Explorer, I have moved it to a new host (the name has been corrected above) and it nows works with IE8 as well as Firefox, though I'm told it still doesn't work with IE7. I don't know why.