201a's transistor subs

[jelin]

i heard someone makes
'wafers" that are electronic substitutes for 201 99 and similar old tubes. they use a transistor, capacitor. and resistor and are placed on a wafer that the old tube sits on (prongs go through holes in wafer) and is a plug in reblacement for these tubes
anyone know of sources for these? thanks, william jelinek

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[exray]

Something like these perchance?

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The Sparkbench

[trainman]

No, they slipped onto the base prongs. No opening of the tube required. I haven't seen those for a long time. Flip through some old ARC issues from maybe five years ago to find the ads for them.

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Tony

[exray]

I've heard of such things and would really like to see how they do a one-size-fits-all drop-in. It would take a novel little ckt to maintain rheostat operation in most sets.

-Bill

[Wayne Richardson]

Bill,
I rember a circuit that used a lamp and photocell to enable rheostat operation.
Think it was in the OTB.

Wayne

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[Norm Leal]

Hi

I added the article under temp.
http://antiqueradios.com/gallery/view_photo.php?set_albumName=temp&id=Fet_Sub

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Norm

[Denny Graham]

Tony's correct Bill, they were advertised in ARC, I don’t subscribe anymore so I don’t know if they are still around.
Power Technology Inc.,
P.O. Box 191117
Little Rock, AR. 72219-1117

Plant Location:
7925 Mabelvale Cutoff
Mabelvale, AR 72103

They are exactly as you describe them, thin G-10 wafers, four holes with spring contacts, a SM 10K pot, four SM chips that look like Sen-Sen marked FY2, A1, RA4 52, LNE 10 and two what I think are, SM resistors marked 391. I bought a few back in “96” but never tried them, I was mostly interested in making some for my self and wanted them for the pattern. I spent many, many hours trying to figure out what the components were. I even enlisted the help of a couple of engineers and physicists at work but we never did figure out what surface mount components would work to replace the 01A’s. There are a dozen or so different articles out there as you can see by the answers you’ve gotten but none are as clean as these were. If the filament was still intact it even lit and you could not even tell that the wafers were on the tubes, looks very original and puts the old run out globes and duds to good use, in my opinion.
Denny Graham
Sandwich, IL
Let us know what you find out.

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[exray]

Sounds pretty cool, especially made to fit with SMD stuff.
Was there any caveat like that they HAD to be used with tubes that were good and dead but still had a good filament? Or would they work on a tube with an open fil...in spite of the rheostat control?
Denny, do you still have one that you can photograph and post here?

-Bill

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The Sparkbench

[Carl Neidert]

Does anyone have a list of triodes that can be replaced with a FET? 6SN7's maybe?

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[Old Radioz]

[OldWireBender]

I'd be interested, Syl.

John

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Money talks. Mine usually says 'goodbye'.

[Old Radioz]

Here it is, hopefully I won't get in trouble with the author...
http://www.oldradioz.com/articles/01asub_1.gif
http://www.oldradioz.com/articles/01asub_2.gif

About 300K per page.

Syl

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[Dale Davenport]

The "wafer" conversions were produced by Tom Burgess of Mablevale / Little Rock. I don't know if he is still producing them or not.

I used a couple of these in an early Crosley some years ago and they worked quite well.

Tom produced some other bits for old radios as well and the quality was good on the items I've looked at.

Tom can be reached as the ~contact person~ for "Arkansas Antique Radio Club," Re: times and places of club meetings. (501) 455-0773. I'm sure a call to Tom will provide information about the availability of the wafer conversions.

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Dale

I don't suffer from insanity,
I enjoy every minute of it.

[radiorobert2]

Jim Fred of Cutler IN produced, advertised and sold these for MANY years but recent health problems left him unable to continue his work.

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Robert too

[Denny Graham]

Yep Bill, I still have three of them be glad to post a picture if I could. All the talk and instructions that have filled these pages about how to download a photo have only made the process more of a problem for me to understand. I still can't figure out how to get a picture across to this forum. I see a lot of guys post pictures along with their post but don't know how they do it. I don't have a web site of my own, don't want one and I don't want to join any more sites, like picturebucket or what ever they call it.
I belong to about 60 Yahoo Groups and all you have to do is drop the file into a picture album and its done. Have loaded many pictures into these.
I made an active probe for my Hickok Multi Meter on the lathe with a vacuum tube in it just like the originals and I've had pictures of it for almost a year I'd like to share but since the best I can do is email it to someone to post for me and I feel like that would wear out my welcome real quick.
Denny Graham
Sandwich, IL

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[exray]

If you'll email the photo to me I'll be happy to post it here.

Thanks,
Bill

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The Sparkbench

[OZ132HOME]

I built a 1L6 Solid State Sub once. Worked O.K.
Was fooling around with my own creation 1U4 IF amp solid state sub for TransOceanics a couple of years ago. Includes a ceramic filter for improved selectivity. Works O.K., but could use improvement from some of you engineering types. I'm just a Tech. Somebody should build these kind of things. I believe there must be a market...

Helped Bill Turner with design of a 50A1 solid state sub which he now sells a year or so ago...He sells an 01A sub that's made with a newer tube, I believe...
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OZ