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 Post subject: Glowing Strelow Solid State Replacement for 01A Tube
PostPosted: Jan Tue 08, 2008 10:57 am 
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I built 5 Strelow style solid state substitutes for 01A tubes and tested them in a Pearson - ERLA PS-5 TRF.
Gary Strelow
in an article in the February 1996 edition of the Antique Radio Classified Magazine describes under "Restoration Topics" "A Tube Substitute that glows". More specifically he proposed and built a replacement of a 01A type triode, which glows like a 01A, has volume control by a rheostat between the filament pins like a 01A - but does not look like a 01A. Thanks to the miniaturization of electronic components it is possible to hide the substitute in the base of a dud 01A, the glass flask of which has been temporarily removed and later glued back. Details and a photo gallery can be found in ref. http://www.greenhillsgf.com/Project_SS-Tubes.htm
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 Post subject:
PostPosted: Jan Tue 08, 2008 11:11 am 
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Without a doubt it looks interesting. Low power consumption and no modification of the radio itself? All for it.

However, it begs one question: After going through so much work to make these replacements look like unmolested 01As, what would happen if one were put in a "normal" radio or tested in a tube tester? For me, if it truly looked like an old tube, it would be easy for me to forget which is which.

Personally, I think I'd rather leave the bulb off or come up with another creative solution.

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 Post subject:
PostPosted: Jan Tue 08, 2008 12:28 pm 
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Why go to all that work?
01A's are still pleniiful and certainly more authentic.


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 Post subject:
PostPosted: Jan Tue 08, 2008 12:28 pm 
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Location: Massachusetts
Other than adding a LED, and photo resistor, it is the same circuit used before when replacing transistors for tubes.

Many years ago I had bud bedker make me some of these tubes, and we both found out that in a radio of over 2 tubes each stage had to be customized to be a good performer. Today there are many other tube options, so why go transistor other than to run it on low power?


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 Post subject:
PostPosted: Jan Tue 08, 2008 12:45 pm 
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Location: British Columbia
I think that I would be more inclined to try using a set of type 30s if I couldn't round up a set of 01As. With most of these substitute plans you have to alter the radio in some way to get it to work, even with the type 30s you would have to do something about the rheostat since 30s draw less current then 01As, but at least you wouldn't have to change anything about the wiring. I have heard of people using IGFET transistors in recreating old tube circuits but these were in scratch built projects, not old radios.
Best Regards
Arran


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 Post subject:
PostPosted: Jan Tue 08, 2008 1:42 pm 
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Location: Marshall Mn
I used solid state on radios I like to listen to just to save my o1As
I can always put them back in


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 Post subject:
PostPosted: Jan Tue 08, 2008 2:58 pm 
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Merrill Bancroft wrote:
Why go to all that work?
01A's are still pleniiful and certainly more authentic.


I can think of several good reasons -

1. - to save your good O1A's
2. - to easily operate your set anywhere (as a portable)
3. - to optimize the life of the interstage transformers and horns / headphones/ etc.
4. - to 'recycle' dud O1A's

I've not done any of this version, but a few years ago I did do several O1A's and 99's from an earlier article in ARC. These don't light up unless the filament is intact - but they work sufficiently. I mark the tube to remind me that it is transistorized. And I agree - don't let the vacuum out - it spoils the look of the tube.

Check this thread for other ideas....

http://antiqueradios.com/forums/viewtopic.php?t=78681&highlight=
Quote:
The article referred to in the initial post was by Dwane Stevens from Antique Radio Classified, Vol. 12 No. 6 June 1995, pgs. 24-26. The circuit can be installed into the base of any dead 4-pin tube. I have used it as both O1-A and UX-199 - it performs fairly well. Here is the diagram:

Image

If you use this concept to replace all the tubes, you can run a simple TRF set and horn with a single 45V power supply (five 9V batteries in series). The tubes won't "glow" but you won't need an "A" supply either. As the article states, for a typical 20's set - "The A-, B-. C- and C+ points are connected together and connected to the negative terminal of battery pack. Likewise, the B+ Power, B+ 67 and B+ 22 1/2 points are connected to the positive terminal of the battery pack. Leave A+ unconnected so that you will be able to turn your radio off and on by using the radio's filament switch."
"If all tubes are replaced with transistor substitutes, the usual way of controlling volume by reducing filament voltage will not work. You must either slightly detune the received station or use a 10K pot connected between the antenna and the antenna-ground input connections of the radio."

You can use the tube in the normal fashion with a standard power supply hookup too. If you use a tube with an intact filament and forego the 20 ohm resistor - the tube will glow. I suggest referring to the original article for other specifics.

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Last edited by jgj6331 on Jan Tue 08, 2008 3:15 pm, edited 2 times in total.

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 Post subject:
PostPosted: Jan Tue 08, 2008 3:07 pm 
Silent Key

Joined: Jan Thu 01, 1970 1:00 am
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Location: Sandpoint, IDAHO 83864
Well, to each their own, I guess. To me it just does not seem right to use solid state devices in a vintage set such as these. And some of these old battery sets are anything but "portable". I guess you could take some lag bolts and attach a couple of kitchen cabinet door handles to them and call them portable. :lol:

I also question the bit about saving the audio transformers. I have had brand new NOS transformers from around 1926 still in the sealed factory box they came in with both windings open. I don't think current flowing thru them is any sort of an issue as long as it is not more than 10mA or so. And I have found that it is often the secondary winding that is open and no current ever flows thru the secondary winding regardless.
Curt

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 Post subject:
PostPosted: Jan Tue 08, 2008 3:33 pm 
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Curt Reed wrote:
Well, to each their own, I guess. To me it just does not seem right to use solid state devices in a vintage set such as these. And some of these old battery sets are anything but "portable". I guess you could take some lag bolts and attach a couple of kitchen cabinet door handles to them and call them portable. :lol: Curt


Come on Curt, I'm trying to be realistic here :? . Of course I'm not suggesting you carry it around like a boombox (although that might be cool with some of the smaller sets :wink: ) - but you could use where there is no accessable AC for a battery eliminator and where you don't want to lug around a heavy battery supply. - ie., like a school demonstration, museum setup, daily driver situations, etc.

(PS - one note - before you label any old tube as a "dud" - make sure you resolder the pins and retest them. I've revived several pricey tubes this way - and don't forget to try rejuvenation as a last resort for low / no emission.)

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 Post subject:
PostPosted: Jan Tue 08, 2008 3:39 pm 
Silent Key

Joined: Jan Thu 01, 1970 1:00 am
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Location: Sandpoint, IDAHO 83864
No problem. I do have one question however. What sort of gain do they offer as compared to an 01A tube? Some of the earlier TRF sets before the release of the Neutrodyne were not neutralized and relied on stopper resistors in the grid circuits to help hold down any self oscillations. I can see if the gain was a considerable amount more than the tube, maybe the set would be full of self-oscillations? Just curious.
Curt

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 Post subject:
PostPosted: Jan Tue 08, 2008 4:29 pm 
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Curt,

I can't comment on chriswch2003's tubes, but I didn't notice any undue oscillations in the few sets I tried mine in - in fact, it seemed less likely to go into regeneration. As far as output, I did no scientific analysis - have no response curves to show you - but, by ear, there wasn't a noticeable difference in performance when everything was peaked out.

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 Post subject:
PostPosted: Jan Tue 08, 2008 7:35 pm 
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Location: Southern NH, 03076
Some ferrite beads slipped over leads of tubes and transistors do wonders for stopping oscillations.

For a battery TRF with SS use a cascade first stage and single devices for the others. It gives plenty of gain. I get full volume from a homemade breadboard I resurrected from the local dump many years ago before the Internet made all the 01A's come out of hiding.

One guy I know uses 2CW4 nuvistors in place of 30's, etc. in battery sets of that era.

Carl


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 Post subject:
PostPosted: Jan Tue 08, 2008 8:33 pm 
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Thank all of you for the lively discussion. Let me make a few comments to what I read:
1. use 30's. I wanted to keep the radio unchanged. 30's require an additional series resistor for the rheostats. Also they don't have a side bayonet pin for holding them in the sockets. They are only 30% cheaper than 01A's, my "tubes" are 95% cheaper
2. 01A's are still plentiful and certainly more authentic. Yes, but not cheap, especially folding in the dud dead or weak "good" tubes, bought on eBay
3. to 'recycle' dud 01A's. This was my primary intention
4. a glowing substitute made from a dud with intact filaments is fine but lacks the volume control
5. one note - before you label any old tube as a "dud" - make sure you resolder the pins and retest them. This standard procedure gave the life back to many 26's, I recovered from Victor R-32 and RE-45 microsynchs, and they were in fact better than average due the "sleeping beauty" effect
6. noticeable difference in performance? Pict.22 of the gallery suggests a 6-fold gain improvement. The "considerable" volume improvement I observed, however, was not as spectacular as that. I did not find any problems with oscillations
7. I am still hoping for suggestions as how to make cheap single sided PCB's


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 Post subject:
PostPosted: Jan Tue 08, 2008 10:29 pm 
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Location: Pocasset, Cape Cod, MA
>>7. I am still hoping for suggestions as how to make cheap single sided PCB's

If the copper pattern is simple enough, cut it with a single-edge razor blade and peel off a strip.


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 Post subject:
PostPosted: Jan Wed 09, 2008 12:53 am 
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Location: Jonesville, MI
chriswch2003 wrote:
Thank all of you for the lively discussion. Let me make a few comments to what I read:
1. use 30's. I wanted to keep the radio unchanged. 30's require an additional series resistor for the rheostats. Also they don't have a side bayonet pin for holding them in the sockets. They are only 30% cheaper than 01A's, my "tubes" are 95% cheaper
2. 01A's are still plentiful and certainly more authentic. Yes, but not cheap, especially folding in the dud dead or weak "good" tubes, bought on eBay
3. to 'recycle' dud 01A's. This was my primary intention
4. a glowing substitute made from a dud with intact filaments is fine but lacks the volume control
5. one note - before you label any old tube as a "dud" - make sure you resolder the pins and retest them. This standard procedure gave the life back to many 26's, I recovered from Victor R-32 and RE-45 microsynchs, and they were in fact better than average due the "sleeping beauty" effect
6. noticeable difference in performance? Pict.22 of the gallery suggests a 6-fold gain improvement. The "considerable" volume improvement I observed, however, was not as spectacular as that. I did not find any problems with oscillations
7. I am still hoping for suggestions as how to make cheap single sided PCB's


Remember, too, that the "XL" (thoriated Tungsten) filamnets used in the general run of 201A and 199 tubes may often be rejuvenated, with excellent results!


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 Post subject:
PostPosted: Jan Wed 09, 2008 2:55 am 
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Alan Douglas wrote:
>>7. I am still hoping for suggestions as how to make cheap single sided PCB's If the copper pattern is simple enough, cut it with a single-edge razor blade and peel off a strip.


Alan, read his website - I think he's talking about making them in large quantities for production and not just a couple for his own amusement (like I did).

vitanola wrote:
Remember, too, that the "XL" (thoriated Tungsten) filamnets used in the general run of 201A and 199 tubes may often be rejuvenated, with excellent results!


That was mentioned about 7 posts back :wink: ....

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 Post subject:
PostPosted: Jan Wed 09, 2008 3:10 am 
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couldn't you use a small hole saw to cut the circular blank from a copper pcb board? Then again a small piece of perf board was used in the early days.


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 Post subject:
PostPosted: Jan Wed 09, 2008 3:18 am 
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chriswch2003... I give up...maybe if they hear it from the horse's mouth (or, at the least, read your website...) :lol:

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 Post subject:
PostPosted: Jan Wed 09, 2008 4:13 am 
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Location: USA
Merrill Bancroft wrote:
Why go to all that work?
01A's are still pleniiful and certainly more authentic.


Makes perfect sense to me, I have sets I'd love to use as daily listeners but don't because of uncommon or expensive tubes in them. The supply of globe 01A's wont last forever (that doesn't mean I won't be able to find them tomorrow- but I AM under 25 and don't expect the ease in finding them to be consistent through my retirement!).

It costs me about $50 (+/- $10) to buy a set of 5 01A's (used globe types) which is enough for one typical 20s o1a set. Just looking around my room I can count around 10 sets in my collection that use such a configuration of 01As.

$50 x 10 = $500, and thats just to have them all equiped without a spare or contingency for damages (for instance hooking up a powersupply incorrectly, moving damages, dropping a tube for some reason, going on an airplane with one-dunno why but who knows what could happen...).

I expect my pile of 20s sets that take 01A's will only increase with time being that I prefer older sets (but will go as far as the late 30s with a few newer exceptions from when the price was right and/or rescues).

If going by economics I'd be more concerned with 45s, 50s etc. but I don't use nearly as many of those in my collection (how often do sets use more than 2 45s?) and have quite a few 45s laying around unused whereas I am always short or exactly stocked for 01a usage. I'm sure all of us could think of oddball tubes that you just don't see often from t this period but I bet alot of these types also aren't used as much as the do-it-all 01A.


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 Post subject:
PostPosted: Jan Wed 09, 2008 5:45 am 
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you can always just have a good set of 01A's, and fill the other sets with duds for appearance.

$10 is a good price for 01A's, prices for them I guess has not increased that much, when I bought some 8 years ago for $8.00

Used to be you could find lot's of early radios with good BBTT 01A's, in the 80's. 95% of them were good tubes.


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