At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me wondering what the tube designers were thinking....

This is the first RF amplifier screen grid tetrode issued by RCA in 1927. It had a 3.3V filament and was made it to go with the UX199 triode tube with the same filament voltage. Unfortunately few other makers used the 199 and this tube did not find wide use. It was used by Scott and a few other makers along with 201As. They used a resistor to drop the voltage from 5V for the 201A to 3.3 for the UX222. Had RCA been smart, they would have made the UX222 with a 5V filament and everyone would have snapped it up.
These tubes are fairly scarce and worth keeping.

:At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me wondering what the tube designers were thinking....

::At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me
wondering what the tube designers were thinking....

Hi, This info may help---

22
Sharp-Cutoff Tetrode

Glass type used as rf amplifier in dry-battery-operated receivers. Requires four-contact socket.

Ralph

I have a Crosley TRF model 26 that uses type 22s.

:::At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me
:wondering what the tube designers were thinking....
:
:Hi, This info may help---
:
:22
:Sharp-Cutoff Tetrode
:
:Glass type used as rf amplifier in dry-battery-operated receivers. Requires four-contact socket.
:
:Ralph
:
:
:
:
:

In addition to the other sets listed here, Atwater Kent made several sets with the 22 (UX222). They offered the Model 67 which came in a metal table model or a console, the Model 61 which had a similar tube line up as the 67 but was designed for New York City 110 volt DC mains and the following year offered the model 70 with the Q chassis all using three type 22's. I have the 67 and it is a good performer.
RCA used them in Radiolas 21 and 22 but these had pot metal chassis and are difficult to restore. The battery version of the Pilot Super Wasp also used a single 22 with three 01A or 112A types. The 2 volt Type 32 introduced sometime around 1930 killed the 22.

Fred R

:I have a Crosley TRF model 26 that uses type 22s.
:
::::At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me
::wondering what the tube designers were thinking....
::
::Hi, This info may help---
::
::22
::Sharp-Cutoff Tetrode
::
::Glass type used as rf amplifier in dry-battery-operated receivers. Requires four-contact socket.
::
::Ralph
::
::
::
::
::

I have a Holmes Jordan battery TRF that uses those tubes. I have had the radio for many years but have not powered it up yet. Electronic design as it advances has many branches that dead end. Some of these branches are the ideas of various engineers. It may not make much sense in retrospect but it made sense at the time. For example: Why vary volume by changing the filament voltage, or why place the volume control in the antenna circuit? This was the best they could do at the time.

Not sure why anyone would vary filament voltage in order to change volume. It is easy, I guess. It introduces distortion at low volumes. It is an easy method of altering volume without altering sound characteristics, though.

The neat thing about the audio taper potentiometer is that if properly built, it doesn't alter audio characteristics much. The trick is building one properly. If you put a resistor in series with an alternating current, the resistor will tend to progressively mute the high frequencies much like a choke, but not as severe. If put in parallel, it will tend to mute the lower frequencies progressively. When put in series, the higher frequencies, which move back and forth quickly, cannot react on the circuit as effectively due to the resistance. This is kind of like vibrating water rapidly and then putting a very thin pipe between it and something you want it to react upon. The higher the resistance, the greater the supression of high frequencies.

Placing a resistor in parallel tightens up a circuit. If a peak of a wave charges up a condenser to a certain amount from where the condenser rests at normally, a lower value resistor is going to discharge the condenser faster than a higher value resistor. This is why you decrease bass when putting a resistor in parallel with an audio circuit. You tighten up the circuit and make it less favorable to bass notes. Decreasing the resistance tightens up the circuit more and more, decreasing bass more and more.

Now taking this all into consideration, if you simply put increasing resistance in series with the audio, you'll reduce the volume, but you will also reduce treble response. If you simply put decreasing resistance in parallel with the circuit, you'll decrease volume, but the bass will be lacking as you get lower in volume. By using a potentiometer, you effectively put more resistance in series with the audio as you put less resistance in parallel with it. As you decrease bass you also decrease treble, and so the two equalize eachother to some degree.....more-so with better controls. Now you can see why this might have been difficult for people to think of at first. Some radios you will find have kind of flat tone in the middle of the control, but treble comes out bright at the top of the control (provided you have some means of reducing the volume of the music so that the amplifier is not overdriven by turning the control all the way up). With other radios you may notice that bass is lacking at the bottom of the control. This is also due to improper design. Some radios have a bass compensator. Some use a tap somewhere mid-way on the control which injects treble muted audio (a tone condenser and resistor combination inject "mellow" bass rich audio here). Others simply place a high value resistor (several million ohms) between the high and the middle terminals of the control. This effectively ensures that bass notes will make it to the center terminal even as the slider approaches the low end of the control.

Regarding putting a volume control at the beginning of the radio, this is logical when you haven't thought of an AVC circuit yet. Otherwise strong stations will distort the RF circuits much like strong audio will distort an audio circuit. Instead of having two volume controls--one for the RF and one for the AF, they simply put one at the beginning. Adequate shielding must be provided, or else radio stations will be picked up by successive stages regardless of where the volume control in the primary stage is set.

AVC offers the advantage of some static supression, and also reduces the fading effect of distant stations. Unfortunately it takes some of the dynamics out of music. Some radio manufacturers came up with circuits which would put the dynamics back into the audio. Crosley used an "Expressionator Tube." It was a resistor in parallel with the speaker output. It would heat up and increase in resistance for a loud passage. When it increased in resistance, it decreased the load on the speaker output, further increasing volume. Strange, but I suppose it was effective. You could also do this with a 2.5 volt .7 or there-abouts ampere lightbulb. I also devised a circuit of my own which I have yet to try which takes the AVC voltage and impresses it on a tube which controls the plate voltage of the 1st AF tube. Not sure if this would work or if it'd introduce distortion. It'd be better to use a pentode for the 1st audio tube than a triode. Then you could simply control screen grid voltage. As the AVC voltage increased (which it does slightly for loud passages), the control tube would increase either the plate or screen grid voltage of the AF tube, depending upon design. You'd want to be able to turn this off if you wanted to supress fading and fluttering of distant stations. For local stations, though, it would bright dynamics back to music. Since AM lacks music these days, though, this is not worth the effort. FM seems to have the same trouble, though. Maybe you could apply it to FM. It annoys me to no end when loud passages of classical music are supressed by the circuitry in my FM radio, especially when I own record copies of the music, and know how it should sound.

Thomas

Another thing is that prior to the advent of indirectly heated cathodes, varying the filament current to change volume would only seem fairly logical and straight forward. After indirectly heated cathodes were invented, designers (whether amateur or professional) were forced to look for other ways of controling volume.

Thomas

:At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me wondering what the tube designers were thinking....

:At a local flea market recently, I found a yellowed box full of NOS type 22 tubes. They're the globe 4-pin type with a grid cap. Can someone tell me what their commercial application was? Specifically, what receivers were they used in? These seem to be late '20s/ early 30s tubes and for the life of me, I can't imagine what sort of sets they were used in and I've been prowling the old radio swaps off and on for 15 years now. I know this is a pretty trivial thing, but it keeps sticking in my head and leaves me wondering what the tube designers were thinking....