WE 306 ringer volume

[TelePlay]

Does the 333 vacuum tube in a WE 306 have an effect on the B3A ringer? The ringer works but at low volume (low amperage it seems). Bench testing the isolated ringer had it ringing much louder.

And if so, I'd there a way to get a stronger ring (and yes, I set the bias spring to its lowest setting and adjusted the gongs).

The phone in question arrived set up for grounded ringing and was rewired to bridged ringing.

[poplar1]

When a telco-owned 306 was converted to a quasi-302 at the WE Repair Shops, the tube was removed and a 1.0 uF capacitor was installed in series with the B3A ringer. The B3A is a low impedance ringer.

The tube is similar to a diode, in the sense that it allows only current of the correct polarity to pass through to the ringer. So, this allows 4-party fully selective ringing, by using grounded ringers and either + on tip side, - on tip, + on ring, or - on ring.

[TelePlay]

The tube is similar to a diode, in the sense that it allows only current of the correct polarity to pass through to the ringer.

So, does that mean when the phone is wired for bridged ringing, the diode, the tube allows only half of the ring cycle to get thru to the ringer? The tube is acting like a wave rectifier?

[poplar1]

I don't believe they were ever used for bridged ringers*. I also don't recall what kind of line you have. It does seem like you would get only the positive half or the negative half of a sine wave. The old WE catalogs reference "pulsating DC" or P.C. current.

I would suggest using a 1.0 uF capacitor in series with the ringer.

(*I vaguely recall extending my party line to a neighbor's house, with one-pair drop wire (no ground), and using a tube so that my line would ring at his house only if ringing current from the Step-by-Step C.O. was sent over the Tip side -- since I was the Tip Party.)

[TelePlay]

I use a Panasonic 616 for phones. When I used a ring generator on the isolated ringer, it rang with the usual volume. So only getting half the ring cycle makes sense.

The tube does flash when a call comes in.

I want to sell the phone so the question is to leave it as is now with bridged ringing (soft ringer), remove the bridge as it was so a ground wire would be needed and the ringer would not work at all without the 3rd line cord wire or replace the tube with a capacitor (no longer a 306).

So the question becomes, keep it as built as a 306, or sell it modified to a 302.

Is a 306 more valuable to a collector (very few coming up on eBay) than a modified 302 (which eBay is full of these days)?

[TelePlay]

There is a lot of information about the 333A and the two other similar vacuum tubes used by WE in party line phones on the forum.

Seems the ring voltage has to be at least 48 volts for the tube to fire. That means that many VOIP and ATAs (providing 24 VAC) not provide a high enough voltage to fire the tube and thus operate the ringer. POTS lines and PBX units have the voltage to ring the phone.

So the question still is to leave it as is, a "working" 306 which are rare on eBay or convert it to a 302 of which there is no shortage on eBay. I'll probably try to sell it as a 306 and if I still have in in 6 months, convert it to a 302.

Here are a couple of links should anyone want to read more about vacuum tubes in telephones:

https://www.classicrotaryphones.com/forum/index.php?topic=99.0
https://www.classicrotaryphones.com/forum/index.php?topic=9471.0
https://www.classicrotaryphones.com/forum/index.php?topic=408.0

More topics exist, search for "333a tube" or some other combination or words relate to tubes.

[TelePlay]

Just a test.

I hooked up my stand alone Dsine ring generator to the phone's line cord. The DSine generates a 70 VAC 20 Hz ring voltage.

When using the Dsine to ring the isolated ringer, the ringer worked at full volume.

When running the Dsine ring voltage through the line cord with the phone on hook, the ringer just barely worked. It rang but just barely.

Switching to the Panasonic 616, the ringer was twice as loud, about as loud as a 500 on its quietest volume setting.

So, it's a voltage/tube issue. The higher the ring voltage to the tube, the better the ring volume. And the half wave rectification is there.

[RDPipes]

I have two 306's one with a 466A tube and one with the 372 tube and as far as I know they both
ring perfectly on my Panasonic 616. I would have had this same question if not. Here's a photo of how one is wired.
Both have the tubes wired in, in fact @poplar1 told me how to wire them I believe.

[MMikeJBenN27]

I have an early 500, (425 A network), with a tube.  It works OK, but it is a little louder if I re-wire it like the city phones.  Moving the the gong on the left further away makes it ring louder, moving it closer makes it ring softer, so you should be able to get it to ring loudly enough.

Mike

[TelePlay]

I have two 306's one with a 466A tube and one with the 372 tube and as far as I know they both ring perfectly on my Panasonic 616. I would have had this same question if not.

Here's a photo of how one is wired.

Both have the tubes wired in, in fact @poplar1 told me how to wire them I believe.

Maybe the tube makes a difference.

One of the topic posts on the forum from poplar1 describes the revised writing verbally

https://www.classicrotaryphones.com/forum/index.php?topic=9471.msg101233#msg101233

that matches the wiring diagram posted by Kenny at this link.

https://www.classicrotaryphones.com/forum/index.php?topic=5374.0

That diagram by Kenny looks like the wiring on your phone, uses only K on the phenolic board (does not use Gnd).

I'll have to try that writing configuration next.

This stacked wiring diagram is the wiring that matches my 306, an image of the phone is also attached.

Note: the solid light green wire attaches what was the yellow ground wire in the line cord to L1 on the coil. The original wiring configuration uses both terminals on the phenolic board.

[TelePlay]

I tried the wiring posted by Kenny C (left side of image below) and found the ringer volume increased 10-20% over just running a bridge conductor from Gnd on the phenolic strip to L1 (the 333 tube yellow wire was connected to L2 in this phone).

Then removed the tube wiring and installed a 2.2 uF 250 V ring capacitor (right side of image below) in series with the ringer and the ringer volume doubled, twice as loud as when using the 333 Tube.

Will leave the tube in the phone with the leads taped off (in case the next owner wants to return it to a 306) and install the capacitor.

Was an interesting problem, lot of stuff on the forum from years ago about tubes and 306 phones, and with the added capacitor the phone is now a nicely working 302.

( Edit Note: final installed capacitor as shown in the attached wiring diagram was a 1.0 uF 250 V metal film capacitor which was a better match to the low impedance B3A 2,000 ohm ringer. )

[poplar1]

The uF value isn't marked on the KS- capacitor. Did you try 1.0 uF instead of 2.2?

It seems you are increasing the REN with a low impedance ringer + a large capacitor.

[TelePlay]

Now I did.

Had two 0.47 uF caps which in parallel provides 0.94 uF.

Tried the 2.2 and 0.94 caps with a decibel meter about a foot away from the phone. Got about 95dB with both capacitors, no difference on volume.

Is there another test that can be done?

[TelePlay]

Hooked up a microphone to capture the amplitude of the ringer for 3 capacitor values.

The 0.47 uF cap was low volume. The 0.94 and 2.2 uF caps were about the same.

Seeing the 0.94 and 2.2 uF caps produce the same volume, is it best to use a 0.94 (1.0) uF cap?

[poplar1]

I searched on the forum for REN info for the Panasonic KX-T616 KSU. One guy said 3.0 for a station port. I had written 6.0 for a group of stations ringing together (EXT 11, 15, 19, and 23, for example). A Central Office line is supposed to be 5.0.

I believe that unbeldi said that a low impedance ringer, such as the 8A ringer in a 534A subset, was equivalent to 2+ REN.

I wish I had more info on the difference in a B1A/B1AL ringer, a "red stripe" B1, and the B3A. Or even the rating on the non-WE KS- capacitor used when converting a 306 to a 302 equivalent.

In any case, I would use the two 0.47 uF in parallel, if that seems to work.

When selling 302 parts on Ebay, I leave the biasing spring in the middle slot of a B1A ringer. I haven't listed any B3A or B2A.