Probably produced in late 1933 or very early 1944 this is the predecessor to the PR-10.
It had been sitting on the garage floor through all of my visits to my friend Oakley's house in Dixon CA. I probably would have never picked it up. It is heavy, was very dirty and was missing all of the mounting hardware - you know, everything loose and sliding around.
But this time I had to bend over and carry it out to the truck at arms length. Did I mention that it was dirty? I don't want to be more descriptive, but, it just wasn't something you wanted to touch. OH(!) what we will do for a historic radio. With all of the dials caked with ?? and the meter upside-down, the metal box was just not the kind of radio that I am usually attracted to. But this time it either had to be saved or risk going to the dump. Oakley is well into his 90s and sharp as a pin but housework was getting to be too much for him. So he was moving.
But this time I had to bend over and carry it out to the truck at arms length. Did I mention that it was dirty? I don't want to be more descriptive, but, it just wasn't something you wanted to touch. OH(!) what we will do for a historic radio. With all of the dials caked with ?? and the meter upside-down, the metal box was just not the kind of radio that I am usually attracted to. But this time it either had to be saved or risk going to the dump. Oakley is well into his 90s and sharp as a pin but housework was getting to be too much for him. So he was moving.
This is the first version of what became the PR-10 communications receiver. It has 10 tubes all of which have 2.5 volt filaments except the 5Z3 rectifier. Audio output is a 59 tube. There is no RF amp all of the gain is in the elaborate IF with a mixer oscillator and 3 stages of IF amplification through an assortment of tuned stages.
One of the differences between this radio and the later PR-10 seems to be the IF frequency. The PR-10 has an IF running at 432.5 kHz but this radio seems to want to be tuned around 450 kHz. Though I could find no specific documentation, the IF was running near 450 kHz when I finished the restoration. I tried to push it down to 432.5 and while it would go there it lost a lot of gain and the BFO just would not work. So simple using performance and what I expected from the range in the IF transformer tuning caps, I reset it to about 452 kHz. I had one IF transformer that was intermittently noisy from a bad ground but I found that and fixed it.
One of the differences between this radio and the later PR-10 seems to be the IF frequency. The PR-10 has an IF running at 432.5 kHz but this radio seems to want to be tuned around 450 kHz. Though I could find no specific documentation, the IF was running near 450 kHz when I finished the restoration. I tried to push it down to 432.5 and while it would go there it lost a lot of gain and the BFO just would not work. So simple using performance and what I expected from the range in the IF transformer tuning caps, I reset it to about 452 kHz. I had one IF transformer that was intermittently noisy from a bad ground but I found that and fixed it.
Band selector shown loosened to allow easier replacement of rubber parts, cleaning and component rebuilding/replacement.
The chassis was in good shape.
The chassis was in good shape.
Tuning cap removed to replace isolation/vibration rubber mounts.
The rubber friction drive components for the tuning mechanisms were also replaced at the stage.
The rubber friction drive components for the tuning mechanisms were also replaced at the stage.
There was no field coil speaker. From what I have read, no one has ever seen one. But it has to be there , Besides the obvious need for audio, the field coil in the speaker is part of the power supply filter.
So I had this Philco 20 speaker laying around. I stuck a new cone in it. The specs on the FC and output transformer were close enough. And it works just fine.
So I had this Philco 20 speaker laying around. I stuck a new cone in it. The specs on the FC and output transformer were close enough. And it works just fine.
Underside view following the restoration with restuffed caps and recast resistors. Only 2 of the original resistors were within 20% of the spec value.
Below is a video of the All-Wave in operation.
A few notes:
It is frequently necessary to "0" the S meter (in this case "R" meter)
The BFO needs to be retuned over time and band changes. You can 0-beat it or just adjust the output for the highest gain on the S meter.
The BFO was intended to receive CW transmissions at the time the radio was built. In the video I use it to generate a carrier needed to demodulate single sideband (SSB). It is not ideally suited for this purpose. The demonstration of the CW reception demonstrates its original purpose. In several of these clips I had not yet found the poor ground in an IF can. So later the noise floor was dropped considerably.
Below is a video of the All-Wave in operation.
A few notes:
It is frequently necessary to "0" the S meter (in this case "R" meter)
The BFO needs to be retuned over time and band changes. You can 0-beat it or just adjust the output for the highest gain on the S meter.
The BFO was intended to receive CW transmissions at the time the radio was built. In the video I use it to generate a carrier needed to demodulate single sideband (SSB). It is not ideally suited for this purpose. The demonstration of the CW reception demonstrates its original purpose. In several of these clips I had not yet found the poor ground in an IF can. So later the noise floor was dropped considerably.
There is a site that has a lot of information on the PR-10 including factory modifications and history. Rather than quote from that site, I recommend that you check it out:
http://www.radioblvd.com/Patterson%20PR-10.htm
Most of the "upgrades" mentioned at the site above were incorporated into this radio. There is a significant difference in the construction of the BFO circuit. I hope that you can make out my notes in the Riders Manual below. Yes, the grid (top cap) is grounded.
http://www.radioblvd.com/Patterson%20PR-10.htm
Most of the "upgrades" mentioned at the site above were incorporated into this radio. There is a significant difference in the construction of the BFO circuit. I hope that you can make out my notes in the Riders Manual below. Yes, the grid (top cap) is grounded.
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