[Eric]

I cut the vibrator can and the contacts were not welded but they were corroded I cleaned them up but I still couldn't get any voltage so I played around with the contact arms for the outside contacts and really got this thing vibrating and got it up to 60vdc across the filter cap and around 90v on the plate of the 7A7 about half what I need.  At least I'm seeing some voltage so the transformer should be ok, I've been playing with the gap and that really varies the output. I suspect some of the spring has gone from the contact arms I might replace this with solid state  unit that I mentioned earlier.

[Arran]

I cut the vibrator can and the contacts were not welded but they were corroded I cleaned them up but I still couldn't get any voltage so I played around with the contact arms for the outside contacts and really got this thing vibrating and got it up to 60vdc across the filter cap and around 90v on the plate of the 7A7 about half what I need.  At least I'm seeing some voltage so the transformer should be ok, I've been playing with the gap and that really varies the output. I suspect some of the spring has gone from the contact arms I might replace this with solid state  unit that I mentioned earlier.

Eric;
 WJOE radio sells DIY Solid State vibrator kits for less then half what the ready made ones sell for. I bought one for the 1954 Chrysler car radio I need to restore. In any event, from what I heard, the main issue with the solid state vibrators is that they don't really use large enough heat sinks on the switching transistors, in fact some rely on just a copper pad on the P.C board to take the heat away. It would not take much of a heat sink to do the job, just a "U" shaped one that would fit a TIP 50 style transistor, you could probably make one out of some aluminum or copper sheet if you didn't scrounge one from some piece of scrap electronic gear.
Regards
Arran

[Radioroslyn]

I cut the vibrator can and the contacts were not welded but they were corroded I cleaned them up but I still couldn't get any voltage so I played around with the contact arms for the outside contacts and really got this thing vibrating and got it up to 60vdc across the filter cap and around 90v on the plate of the 7A7 about half what I need.  At least I'm seeing some voltage so the transformer should be ok, I've been playing with the gap and that really varies the output. I suspect some of the spring has gone from the contact arms I might replace this with solid state  unit that I mentioned earlier.

Eric;
 WJOE radio sells DIY Solid State vibrator kits for less then half what the ready made ones sell for. I bought one for the 1954 Chrysler car radio I need to restore. In any event, from what I heard, the main issue with the solid state vibrators is that they don't really use large enough heat sinks on the switching transistors, in fact some rely on just a copper pad on the P.C board to take the heat away. It would not take much of a heat sink to do the job, just a "U" shaped one that would fit a TIP 50 style transistor, you could probably make one out of some aluminum or copper sheet if you didn't scrounge one from some piece of scrap electronic gear.
Regards
Arran

Hi Arran,
How are they rf wise? Do they generate rf noise and or harmonics? Dad use to service 2 way radios back when I was a kid in the 60's so I always had a good supply of mechanical ones. Nowdays I try to stay away from as they are a pitb!

[Eric]

Ok I have something going on with this so here is some more Info which is probably relevant.
I'm using a 6 / 12 volt car charging unit set on 6v hooking it up with the positive going to the frame. I do not have the speaker he is working on getting me a proper speaker so I'm using a 5" speaker with a output transformer mounted on it I can get static pop when I touch the speaker leads from the radio leads. Is this ok?
 I have rechecked all resistors and replaced any that were over 20%. When I power up I get 230v from pin 8 of the OZ4 but it quickly goes down to 60v and I'm getting roughly 50% of what I should get on the 7A7rf tube . I have a solid state replacement that acts the same way do I have a problem with the OZ4?

Eric
Going crazy down in Georgia!

[Kenneth F. Besso Jr.]

Only thing I can thing of ,,,,is the charger can't deliver anough amps to keep up,,,,so it falls off----MAYBE

[Eric]

Only thing I can thing of ,,,,is the charger can't deliver anough amps to keep up,,,,so it falls off----MAYBE

Kenneth
It's a 6 amp charger and the meter goes to 8 amp, when I turn it on it goes to 4-5 amp and goes down to about 2 amps ( as the voltage starts out at about 300v and decays to around 100v need 200v). I got the solid state vibrator and it does the same thing. So the plate voltages are about half of what thay should be.  I'm thinking the transformer is ok or it would draw high current or not work at all.

Eric
"Know wonder I'm bald the way I scratch my head"

[Eric]

Ok I have some more data.
With the SS Vibrator across resistor 34 ( small pins) - 4.5vac ( after peaking at 9.5vac).
Across Cap 19 (.004) the plate pins of the OZ4 250vac
At K pin 8 of the OZ4 135vdc
I'm wondering if the problem is in the Oz4 or do I have my filter caps in backwards? they are connected with the neg side going to Ground. Since the radio is a positive ground?
Eric

[Radioroslyn]

Is your 6v charger putting out 6v under load? Is there a full 6v going into the set? Typically chargers don't have any filtering so the dc output has a lot of ripple. Try adding a 6v car battery or a large cap like 10,000mf @ 20v or so to eliminate the ripple. If you have a full 6v at the set measure the ac voltage from plate to plate of the 0Z4. Should see about 500vac or better. If you do then chuck the 0Z4 and solder in two 1N4007. Tie the banded ends together and solder to the cathode pin of the socket. The unbanded ends go to each of the plate pins. I suspect your 0Z4 is weak.

You should be able to use a pm spkr as the only thing that the fc is doing a providing magnantizum for the spkr, and draining the battery.

[Eric]

Is your 6v charger putting out 6v under load? Is there a full 6v going into the set? Typically chargers don't have any filtering so the dc output has a lot of ripple. Try adding a 6v car battery or a large cap like 10,000mf @ 20v or so to eliminate the ripple. If you have a full 6v at the set measure the ac voltage from plate to plate of the 0Z4. Should see about 500vac or better. If you do then chuck the 0Z4 and solder in two 1N4007. Tie the banded ends together and solder to the cathode pin of the socket. The unbanded ends go to each of the plate pins. I suspect your 0Z4 is weak.

You should be able to use a pm spkr as the only thing that the fc is doing a providing magnantizum for the spkr, and draining the battery.

Terry.
I get 8vdc when I turn it on it drops to 6v, across the plates of the OZ4
I get 250v  Don't have the diodes but I will get them. 

[Radioroslyn]

If you are getting only 250vac from plate to plate (not plate to chassis) that equals about 100vdc at the rectifier cathode (too low). Do you have 6vac at the transformer's primary? If so I'd add a large cap across the 6vdc charger. If not vibrator contacts are bad.

[Eric]

Terry
I think I'm narrowing it down I changed chargers I have a 10amp charger so I'm getting a bit stiffer supply. I found an old package of Archer 1000v 2.5 diodes so I wired them like you said. I get better voltages . Across the plates I get about 310 and at K pin 8 190v which calls for 240v. Now I get a lot of hum through the speaker I can get a station but the hum is overwhelming so I either have to get hold of a 6 volt battery or get the. 10,000mf cap you mention the best I have around here is 1000 mf 16v I may go to Fry's tomorrow and see what they have.

[Radioroslyn]

Great! Sound like your making good progress. You can give the 1000mf cap a try to hear if it lower the hum a little.

I suspect that the dc out of your charger causing your HV to be low. The output of the charger is pulsed dc, in other words every one 60th of a second there is no voltage at the 6v output. The filter cap charges up when there is a 6v pulse then where it drops to zero on the negative cycle the cap will discharges and fills in that (negative) no voltage cycle.

Think of it like this you are walking along using both feet and the walking is nice and smooth. Take one of your legs and tie it so your foot is up in the air. Now you can walk but it's not so smooth rather jerky. This because you aren't able to use both feet only. The filter cap acts like your other foot to smooth out pulses. It holds up the dc voltage when there isn't any.

[Eric]

I got the 6v battery, It powers up and I get a wide variety of stations I still get a little hum from the speaker. I have tried both the SS vibrator and the original ( the original I have to give a helping hand to start vibrating so I'll stay with the SS) the hum is a little different in tone but still there. I'm just using a 4' PM speaker I had laying around. The speaker in the Schematic seems to show an inductor coil I'm I correct? My friend is working on getting a proper speaker for that model car.

[Radioroslyn]

I got the 6v battery, It powers up and I get a wide variety of stations I still get a little hum from the speaker. I have tried both the SS vibrator and the original ( the original I have to give a helping hand to start vibrating so I'll stay with the SS) the hum is a little different in tone but still there. I'm just using a 4' PM speaker I had laying around. The speaker in the Schematic seems to show an inductor coil I'm I correct? My friend is working on getting a proper speaker for that model car.

< I'm just using a 4' PM speaker I had laying around.
Dang that's a biggin!!!!!

< Schematic seems to show an inductor coil I'm I correct?
Yes! But look at how it's wired. It's not wired as part of the HV filter. It's the field coil for the spkr and it provides the magnatizim for the spkr. It's powered by the 6v power from the battery. This won't reduce the hum level. There are two small caps connected to the VC, these are used to block rf generated from the vibrator contacts (arcing).
My take on this is that a regular pm spkr should work fine. I would try adding a bit more capacitance to the filters like 10 or 20mf to hear if that helps reduce the hum level. Also try connecting an earth ground to the cabinet, this may help w/rf pickup from the vibrator.

[Eric]

Ok I was out of town for a few days but I'm on it again right now I'm running it off a 6v battery, I'm not using the 0Z4 but the diodes you suggested, The filter caps are both 22mf @350v. I couldn't sometimes get the vibrator going so I have been using the Solid State Vibrator ( I figure once this is in the dash he won't be able to smack it to get it going). I've noticed it hums regardless which vibrator I use just the pitch is a little different. Grounding doesn't seem to make a difference. Shrunk the 4' speaker down 4 " not easy, tried a variety of PM speakers but all pretty much the same.

Eric