I'm in the really OLD radio and SET clubs now.

radio, tape, stands and accessories
Big B5515
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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 24 Apr 2017 11:01

Another addition to my collection that fits this thread topic from ~1924 using 5- 01A triodes, a Freed Eisemann NR6, already nicely restored. As nice as it looked, I just couldn't pass it up for $50
380493805038051
Coupling transformers, 2 capacitors, and grid leak resistor were replaced, but original parts and documentation were in a box found with it. I will have to do some research on an appropriate speaker, and improvise a power supply to test it, records from previous late owner show settings for 3 stations, just over 1200khz being highest possible frequency.

Coffee Phil
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Re: I'm in the really OLD radio and SET clubs now.

Post by Coffee Phil » 24 Apr 2017 20:36

Hi Big B,

Congratulations! I think you did pretty well there.

I'm thinking a horn driven by a a diaphragm type driver or a balanced armature cone speaker like I bought for my Radiola will be the most correct and will be the loudest. A permanent magnet moving coil speaker and transformer matched to about 5 K-Ohm will work but it won't make your ears bleed.

Sadly I haven't done anything with my Radiola TRF radio yet. The 1940 Wards is ahead in the Q and I even violated my rule of "no more shiney objects" before finishing the ones I have.

I'm in the midst of the old Admiral 78 changer, which at your suggestion may go on top of the Wards Airline.

Buy the way, where did you get the power transformer for you phono oscillator? I'm thinking of building a triode stage to EQ and buffer the still working 72 year old Shure crystal cartridge in the changer and I'll need a power supply. The EQ is based on a circuit in the 1947 Shure catalog.

Phil

Big B5515 wrote:Another addition to my collection that fits this thread topic from ~1924 using 5- 01A triodes, a Freed Eisemann NR6, already nicely restored. As nice as it looked, I just couldn't pass it up for $50
380493805038051
Coupling transformers, 2 capacitors, and grid leak resistor were replaced, but original parts and documentation were in a box found with it. I will have to do some research on an appropriate speaker, and improvise a power supply to test it, records from previous late owner show settings for 3 stations, just over 1200khz being highest possible frequency.

vinyl master
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Re: I'm in the really OLD radio and SET clubs now.

Post by vinyl master » 24 Apr 2017 21:41

That Freed Eisemann is sure a classy looking piece of equipment there, Big B! 8) Love how you always come away with something new and different each time! Your Grundig should be fun, too! :D

Big B5515
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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 26 Apr 2017 10:11

Phil, On that transformer, I bought it from Angela's instruments http://www.angela.com/hammondlowpowerbi ... 62e12.aspx Although you might check these guys in AZ as well & compare shipping if you need a 6V heater version as the're closer to you than NY or MD. https://www.tubesandmore.com/products/t ... s-120v87ma. On finding a speaker, I'm wondering if the radio would have originally been sold with a speaker made by same company, or if they were often sold with some other brand.

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Re: I'm in the really OLD radio and SET clubs now.

Post by Coffee Phil » 26 Apr 2017 19:56

Hi Big B,

I'm thinking your radio is from the period when radios were largely owned by hobbyists who assembled their setup much like computer hobbyists of the '80s. RCA did make speakers such as the Radiola 100 which I bought for my Radiola 17/18 ? radio. I think you were expected to purchase them separately. I would guess that when your radio was new there would have been some mixing of brands. Since your radio is battery powered I'm guessing it may have less output power than my Radiola so you might seek a horn speaker. I think they would be more efficient than my balanced armature Radiola 100.

Thanks for the link. The transformer which you used is larger than the one which I used in 1960 for my phono oscillator. That may be as small a combined plate and filament transformer as there is now. I still have not decided how I'm going on the power supply. The plan was to use Shures' 1947 catalog input network followed by a cathode follower. Most likely I'll use a 12Au7 and parallel the sections for the signal, but I'll bias the cathodes separately at ~5 ma each. I will need about = +100 Volts @ 10 ma for the plate and ~ -12 volts to make the quasi current sources for the cathodes. I plan to use 12 Volts DC to light the tube and use that for the cathode current source as well. I have some tiny 1:1 transformers which with a bridge and filter can do the plate supply. I'm playing with a 12 V, 0.5 A switcher like I'm using to power my B&O turntable motor. I'd like to use it, but there is an issue with switchers and tube heater loads. Even the 150 ma heater pulls more than 0.5 A when cold. The little switcher shuts down and retries several time until the heater warms and starts to draw less current. It gets there in several tens of seconds but seems flakey to me. I'll try a soft start circuit with a MOSFET and if it doesn't seem too much bother I'll go that way. Otherwise I'll have to get the plate and filament transformer and use a bridge for my -12 Volts as well as the plate supply. The thing which is complicating the 6V / 12V decision is that I just just found a 6111 tube in an box of junk. It is a dual triode fairly similar to the 12AU7 but is about the diameter of a TO-5 transistor and is as cute as can be. It is 6.3 volt heater only. Call me silly, but I'm thinking of having the tube poke out of the top of the plinth on which I mount the changer.

Phil
Big B5515 wrote:Phil, On that transformer, I bought it from Angela's instruments http://www.angela.com/hammondlowpowerbi ... 62e12.aspx Although you might check these guys in AZ as well & compare shipping if you need a 6V heater version as the're closer to you than NY or MD. https://www.tubesandmore.com/products/t ... s-120v87ma. On finding a speaker, I'm wondering if the radio would have originally been sold with a speaker made by same company, or if they were often sold with some other brand.

Big B5515
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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 30 Apr 2017 06:25

I did come across an old picture of the Freed Eisemann with a horn speaker resembling maybe a Radiola, Magnavox, or similar, I'll keep my eyes open for one. It only has the power output available from the plate of a single 01A with 90V to work with, and an extra AF stage if needed. I'm debating the best solution to power it, I assume it needs 6V (actually 5V after rheostat) for heaters at 1A(med)- 1.25A(loud), and unknown current at 90V, tapped at 45V. I considered trying 9V batteries for B battery, but doubt I'd get much usable life from a 6V dry battery at 1.25A. I've considered building a power supply, but doubt this radio will get much actual use. Many of it's capacitors were tested and not changed, only 2 were replaced, and marked bad or off spec. on schematic. One old coupling transformer had open 1kohm primary, other had open 10kohm secondary.

Hammond does have some smaller transformers (see Angela's selection of low power\ bias transformers), and tubesandmore.com had a smaller one in 6.3V somewhere in their listings (under AES, APEX, or one of their names) at one time for their transmitter kit. I chose the 87ma as it was the cheapest from Hammond, and the other was too undersized for using 2 tubes I thought. On the 6111, are you talking about one of those little metal tubes like a 6DS4 (I came across 3 from old TV tuners while looking in my old transistor & IC drawer)?

Coffee Phil
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Re: I'm in the really OLD radio and SET clubs now.

Post by Coffee Phil » 30 Apr 2017 08:28

Hi Big B,

The 6111 is not a Nuvistor. It is a glass double triode much like a 12AU7 but much smaller in diameter. It is an 8 pin or more precisely leads. It is supplied with 1.5" leads. Mine has the leads cut short and is in a socket very much like a transistor in the '60s.

According to the data sheet these tube are very robust and they even spec the microphonics at 15G.

I've had this in my junk stash for more than forty years and didn't even know such a tube existed until a few days ago. Before considering using it I checked and found that I don't own the only surviving example. If I end up using it I'll get some spares on eBay.

here is link to the data sheet:

http://www.mif.pg.gda.pl/homepages/fran ... 6/6111.pdf

I'll try to photograph it next to a 12AU7 for comparison.

Phil

Big B5515 wrote:I did come across an old picture of the Freed Eisemann with a horn speaker resembling maybe a Radiola, Magnavox, or similar, I'll keep my eyes open for one. It only has the power output available from the plate of a single 01A with 90V to work with, and an extra AF stage if needed. I'm debating the best solution to power it, I assume it needs 6V (actually 5V after rheostat) for heaters at 1A(med)- 1.25A(loud), and unknown current at 90V, tapped at 45V. I considered trying 9V batteries for B battery, but doubt I'd get much usable life from a 6V dry battery at 1.25A. I've considered building a power supply, but doubt this radio will get much actual use. Many of it's capacitors were tested and not changed, only 2 were replaced, and marked bad or off spec. on schematic. One old coupling transformer had open 1kohm primary, other had open 10kohm secondary.

Hammond does have some smaller transformers (see Angela's selection of low power\ bias transformers), and tubesandmore.com had a smaller one in 6.3V somewhere in their listings (under AES, APEX, or one of their names) at one time for their transmitter kit. I chose the 87ma as it was the cheapest from Hammond, and the other was too undersized for using 2 tubes I thought. On the 6111, are you talking about one of those little metal tubes like a 6DS4 (I came across 3 from old TV tuners while looking in my old transistor & IC drawer)?

Big B5515
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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 30 Apr 2017 12:41

I've heard of subminature tubes, but never ran into any except for the Nuvistors. I for a while did not realize these were actually tubes, so they ended up in the sand drawer. I do recall one other compact unusual tube in the VFO section of a old higher powered army surplus signal generator. It had a flat top (I think), unusual connections and didn't look to fit in with the other octal base tubes in unit. This forgotten brand signal generator could transmit a good sounding modulated signal at least a mile or so with a decent antenna.

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Re: I'm in the really OLD radio and SET clubs now.

Post by Coffee Phil » 01 May 2017 02:36

Hi Big B,

There is a Nuvistor well suited for this. It is the used in the input stage of my otherwise solid state Fairchild oscilloscope. It works well with a 25 Volt anode supply. It is ceramic and glass so you don't see anything glow. Since I plan to have the tube visible, what fun is some tube which looks a transistor.

Here is the little tube with a 12AX7 for comparison. Also shown is the socket for the little tube.

[img]38078[/img]

Before I found the little tube I was planning a 12AU7. The plan was to use a 12 Volt 0.5 A switcher to light the tube and supply -12 volts for the cathode current source. The switcher had trouble starting with the 12AU7 heater load.

The 6111 is 6.3 volt heater only and I wanted more for my cathode current source. It occurred to me that I could use a dropping resistor for the heater and even though the initial starting current would be nearly 600 ma it may be more gentle for the 500 ma switcher. I just did the experient. The switcher starts without hesitation and within ~600 mS the current is well under 500 ma. In about 15 seconds the little tube has the lovely glow. I think I'm on the way with the little tube.

Phil
Big B5515 wrote:I've heard of subminature tubes, but never ran into any except for the Nuvistors. I for a while did not realize these were actually tubes, so they ended up in the sand drawer. I do recall one other compact unusual tube in the VFO section of a old higher powered army surplus signal generator. It had a flat top (I think), unusual connections and didn't look to fit in with the other octal base tubes in unit. This forgotten brand signal generator could transmit a good sounding modulated signal at least a mile or so with a decent antenna.

Big B5515
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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 18 Feb 2019 19:11

While I did recently see a early Atwater Kent (IIRC) horn type radio speaker that "would" have been suitable for the Freed Eisemann in a local antique and musical instrument shop, It had been all but cosmetically destroyed. To my horror, it had been repainted with a green crackle finish sort of simulating corroded copper, and now had a modern cord to connect to a 1\8" headphone jack. I thought about returning with an ohmmeter to see if it even still had it's original high impedance driver, but decided I did not want to shell out the $165 (firm) I really didn't have to spare for this eyesore I would then have to strip and re-restore :-& #-o . While I had at one time bought 10 cheap 9V and 4 alkaline D batteries for a test run, I too have yet to even find the time to try to power this one up with a pair of old headphones.

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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 21 Mar 2019 04:09

I made it back to where I had seen that old speaker, this time with a multimeter. Unfortunately, not only was it repainted and rewired, it now has an 8 ohm driver.
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:-({|= Or in other words, I'm still hunting for a speaker.

vinyl master
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Re: I'm in the really OLD radio and SET clubs now.

Post by vinyl master » 21 Mar 2019 05:04

Don't worry, B...You could always ask on here or maybe the antique radio forums...Maybe someone might have one...I could also keep a lookout at my antique fair in the summer (May, July, September) or my Vintage Electronics Expo, when it comes around next January...I could've sworn I'd seen some similar items in the past... :-k

Big B5515
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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 29 Apr 2019 01:12

I may have finally found that early radio speaker I was looking for, a RCA UZ 1325 Radiola loudspeaker, or at least hopefully a usable one until a better match comes along. While the driver base could stand to be repainted, this one measures 1.7K ohm and does still produce sound when connected to AF signal generator. While I don't have to "unrestore" it, the price was no lower than the green monstrosity in my last post. With some fresh batteries and a bit of luck, maybe I can now give my earliest radio so far a test run in the near future, last done and documented ~20 years back by it's previous owner.
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vinyl master
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Re: I'm in the really OLD radio and SET clubs now.

Post by vinyl master » 29 Apr 2019 02:39

Ooohhh! That is looking very nice, B...I'd love to see a pic or a video of it with your radio when you get it all set up...By the way, am I seeing some more goodies there, as well??? :-k

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Re: I'm in the really OLD radio and SET clubs now.

Post by Big B5515 » 14 Oct 2019 08:24

I finally got around to trying out the Freed Eisemann tonight, after picking up a 6V, 5AH SLA battery for it's heater power. I had bought the 9V batteries over a year ago, which were a little weak from the start, but after 3 hours, the heater battery was about discharged, and the 10- 9V batteries in series were still at 81V. It was a bit tricky trying to find a station, I finally used the signal generator to figure out dial settings for 650 and 740, both of which I was then able to tune in. Unless listening to a weak signal, the extra gain of the last tube only made sound more distorted, the medium level output usually sounded clearer and reduces current draw, as last tube's filament only has power when speaker is plugged into loud connector. The volume level was not exactly loud either way, and sound quality is nothing to write home about. As the last tube was more sensitive to heater voltage, I suspect it may be weak, however it seems I heard 01As are only good for maybe 100mw, or so as a AF amp. I've yet to check the tubes, or do anything to it yet, but noticed that I do need to try to tighten up the center dial's variable capacitor which now turns a little too easily.
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