[TA Forbes]

You might consider the Playthings of the Past web site. Gary may have a good vibrator there, wouldn't be surprised if he has an NOS one.

Also, you might consider one of the solid state vibrators out there. They are quieter and use less power.....

With respect to power sources, there are MANY batteries and chargers out there. Several are for burglar alarms.... they have an adequate amount of power to run your set for two to three hours. There are also small plug in chargers that do a great job recharging your 6V battery.

Of course there are also the small lead/acid 6V batteries used for lawn mowers, etc....

[BrendaAnnD]

Power-Sonic makes some quite large 6V gel cell batteries. I have one here that's 56Ah. I believe they have one that's in the 80's, but it's too heavy to ship here.

[BrendaAnnD]

BTW, he mentioned Gary's site in his original post.

[Arran]

You can also run one of these sets by putting 6.3 volts AC directly into the primary of the vibrator transformer, but you would need to replace the synchronous section of the vibrator with a pair of silicon diodes. However the tube filaments will require clean DC as they are battery tubes, otherwise the set will either not work or hum at least. I don't know if you can do this for the long term or not as the vibrator transformer is designed to operate at around 110 cps not 60 cps, maybe they can take the abuse since vibrators, by the nature of the contacts opening and closing, produce a voltage spike.
Supposedly you can clean a vibrator by connecting a 40 watt light bulb in series with it and running it off the AC mains, I have not tried this however. I would go with a solid state substitute, either bought or home brewed, then as long as the hash capacitor is in good order it should run reliably for years.
Regards
Arran

[TA Forbes]

Brenda: yes, that's what I had in mind. I had a 6V27 that Bob Timms had done a superb job restoring. Among other things it had a solid state vibrator and it lasted several hours on a burglar alarm battery that was, I believe, a 7.5 a/h. It used a small plug-in charger that was similar in appearance to one that you would use for your phone.

ANYWAY, it was a neat set up, and although I traded it for my Sparton 1568, I miss having a set that could be powered by a single 6V battery.

[BrendaAnnD]

I have a really nice GE 6 volt radio. I it's a U-70 http://www.radiomuseum.org/r/general_el_u70.html. Hot little 3 band set with an RF amp and two IF's, push-pull audio (19) and a narrow/wide band switch. http://www.nostalgiaair.org/PagesByModel...008271.pdf

[TA Forbes]

That's a neat set!! RCA always gets a lot out of their sets by design.

The 19 tube is used in a lot of "other-than 120V" powered sets. Its a pretty good output tube and provides a PP output!

While you often see 6V tubes in vibrator sets, it is interesting that RCA went with the 2V filament "battery set" tubes.

[bfrohwein]

Wow.. I wasn't being emailed there were more replies to this post. I must've unchecked something.

I'm back.. this time with another snag.. I got everything up and running but I wasn't getting hardly any sound out of the speaker. started poking around and found no plate voltage on the 30 tube in the driver stage. I thought I'd tested the input Transformer but apparently, I either hadn't or had missed that the primary is open.

it's #69 on the schematic. philco part number 32-7454.

[Image: http://i1303.photobucket.com/albums/ag14...8bd1e2.jpg]


Any ideas on a replacement? it looks like it's a 10,000:10,000 audio transformer

I'd hate for this to be the show stopper.. it may be though. Would be a Shame as this has been a very time consuming restoration.

[BrendaAnnD]

This one should work pretty well for you:

http://www.tubesandmore.com/products/P-T124B

[Mondial]

Brenda, I am not sure how well that transformer would work in his set. The Hammond transformer has a 1 to 3 step up ratio for the usual driver plate to class A push pull grids.

The type 19 tube operates in class B and requires that the tube grids be driven positive. Since the grids draw current when positive they present a fairly low impedance load to the transformer. Usually a Class B driver transformer has a step down ratio of 2 to 1 or even 3 to 1.

Maybe he would be better off if he could find a replacement from another junk radio using a 19 output tube or get one from Playthings of the Past. I don't think small replacement Class B driver transformers are currently being made.

[bfrohwein]

It was late when I posted that, so I didn't look around as much as I should have. what about solution B in this article by Ron?

http://www.philcoradio.com/tech/audio.htm

or

how about the 124D from Hammond.. it's not exact but it's closer than the 124B?

http://www.hammondmfg.com/pdf/124D.pdf

[Mondial]

Yes, that transformer would be much better but you would want to use it reversed so it will have a stepdown ratio.

Connect the full secondary winding to the 30 tube plate circuit and connect the 19 tube grids to the tapped primary and you will be pretty close to the original.

Using the resistor load and coupling cap in place of the open primary will work to some extent but not very well as the driver stage needs to supply significant audio power to the 19 grids. You are much better off with the replacement transformer.

[bfrohwein]

Thanks, Mondial. it's a bit cheaper too. I thought I'd tested that transformer on this before I decided to restore it. I tested all of the coils, chokes and other transformers. the primary was open on the output transformer too. Started to wonder what happened to this poor thing in the past. 12 volt battery connection maybe or just my luck?

perhaps I'll try the coupling cap to see if I uncover anything else before I leap in and spend another chunk of change on another transformer. It's got other issues as well. the hash is terrible, for one thing. The Cabinet is yet another sad tale. :-)

[bfrohwein]

and I'm back...

well modification B certainly woke up this radio. I'm getting sound and tuning in stations. the output quality isn't all that great, and the droning of the vibrator coming through the speaker is rather unpleasant. my plate voltages are a bit low on

Since I've never done a vibrator type set before, I assume you shouldn't really hear this, right?

I also assume the dial light shouldn't be pulsing either?

[BrendaAnnD]

Have you replaced the caps in the vibrator section? Those are VERY critical, and if they are leaky/shorted, they will cause these symptoms.