Dial Speed Tester 43 - UK Vintage Radio Repair and Restoration Discussion Forum

gpogal · 6th Mar 2011, 9:31 pm

Hi, does anyone know how to wire an old 1950's dial speed tester. The markings on the back indicate its a No 43. It only has two connection and I have tried to put it in series with a normal line, with no joy:-( Alternatively does anyone know of a cheap modern pulse dial tester? I want to make sure the phones I restore are as near to 10pps as possible

russell_w_b · 8th Mar 2011, 7:02 pm

The speed-tester 43 is a mechanical device with an electromagnet and a mechanical movement. You'll need to wind the handle in an anti-clockwise direction first of all. The lower pointer is a measurement of impulse frequency against a scale calibrated in impulses-per-second.

The upper pointer (the ring) indicates the number of impulses received.

I have no experience of these things other than reading about them, but I would suggest putting a 50V d.c. supply in series with one of the two terminals, with one leg of your dial pulse contacts going to other terminal. Connect the other leg of your dial pulse terminal to the other side of the 50V supply.

+VE 50V d.c. >> Dial speed tester terminal 1 >> Dial speed tester terminal 2 >> dial pulse contact 1 >> Dial pulse contact 2 >> -VE 50V d.c. supply.

Rotate the lever fully anti-clockwise so the spring is charged in the dial speed tester.

Rotate the dial and let go. See what happens!

gpogal · 13th Mar 2011, 10:00 pm

Russell, many thanks you have confirmed my thoughts. Does anyone know where I can get a cheap 50v DC suppy from?

russell_w_b · 13th Mar 2011, 10:44 pm

Quote:

Originally Posted by gpogal

Does anyone know where I can get a cheap 50v DC suppy from?

Try it on 12V first (wall-wart, car battery) just to see. Is there anything written on the electromagnet within - current, resistance, voltage?

Chipmunk · 23rd Apr 2011, 5:58 am

The 'in series with a 50v supply' sadly won't work with a Number 43 tester. I have one I use all the time. They step when connected, rather than when disconnected, and a dial disconnects. (hope that makes sense). They'd have been used with an impulse accepting relay at the exchange. The coil of the tester I believe is 350 ohm, I use mine on 36v from an HP printer PSU (check car boot sales etc). The psu has a +24v and -12v supply, which seems to operate it fine. The relay is fairly non-critical, as you have no line length to distort the impulses, but 1-200 ohms would provide the limiting needed to run the phone, mine uses a 300 Ohm relay coil.

As a power supply, you could probably use 3 or 4 pp3 batteries in series, as the current consumption is pretty low when not directly pulsing. I've attached a diagram (hopefully) that I knocked up quickly. It's important when running on batteries to include an on/off switch, as with no phone connected, the coil of the tester is energized. (It energizes during breaks in the line current)

Hope all this makes sense!

One final tip, don't try to reset the lever of the 43 tester when it's energized (IE if the phone's off hook or disconnected), it'll fight back! (done that a few times!)

6th Mar 2011, 9:31 pm	#1
gpogal Retired Dormant Member Join Date: Dec 2006 Location: Barnsley, South Yorkshire, UK. Posts: 12	Dial Speed Tester 43 Hi, does anyone know how to wire an old 1950's dial speed tester. The markings on the back indicate its a No 43. It only has two connection and I have tried to put it in series with a normal line, with no joy:-( Alternatively does anyone know of a cheap modern pulse dial tester? I want to make sure the phones I restore are as near to 10pps as possible

8th Mar 2011, 7:02 pm	#2
russell_w_b Dekatron Join Date: Jul 2007 Location: Penrith, Cumbria, UK. Posts: 3,687	Re: Dial Speed Tester 43 The speed-tester 43 is a mechanical device with an electromagnet and a mechanical movement. You'll need to wind the handle in an anti-clockwise direction first of all. The lower pointer is a measurement of impulse frequency against a scale calibrated in impulses-per-second. The upper pointer (the ring) indicates the number of impulses received. I have no experience of these things other than reading about them, but I would suggest putting a 50V d.c. supply in series with one of the two terminals, with one leg of your dial pulse contacts going to other terminal. Connect the other leg of your dial pulse terminal to the other side of the 50V supply. +VE 50V d.c. >> Dial speed tester terminal 1 >> Dial speed tester terminal 2 >> dial pulse contact 1 >> Dial pulse contact 2 >> -VE 50V d.c. supply. Rotate the lever fully anti-clockwise so the spring is charged in the dial speed tester. Rotate the dial and let go. See what happens! __________________ Regds, Russell W. B. G4YLI.

13th Mar 2011, 10:00 pm	#3
gpogal Retired Dormant Member Join Date: Dec 2006 Location: Barnsley, South Yorkshire, UK. Posts: 12	Re: Dial Speed Tester 43 Russell, many thanks you have confirmed my thoughts. Does anyone know where I can get a cheap 50v DC suppy from?

23rd Apr 2011, 5:58 am	#5
Chipmunk Triode Join Date: Mar 2007 Location: Southampton, Hampshire, UK. Posts: 30	Re: Dial Speed Tester 43 The 'in series with a 50v supply' sadly won't work with a Number 43 tester. I have one I use all the time. They step when connected, rather than when disconnected, and a dial disconnects. (hope that makes sense). They'd have been used with an impulse accepting relay at the exchange. The coil of the tester I believe is 350 ohm, I use mine on 36v from an HP printer PSU (check car boot sales etc). The psu has a +24v and -12v supply, which seems to operate it fine. The relay is fairly non-critical, as you have no line length to distort the impulses, but 1-200 ohms would provide the limiting needed to run the phone, mine uses a 300 Ohm relay coil. As a power supply, you could probably use 3 or 4 pp3 batteries in series, as the current consumption is pretty low when not directly pulsing. I've attached a diagram (hopefully) that I knocked up quickly. It's important when running on batteries to include an on/off switch, as with no phone connected, the coil of the tester is energized. (It energizes during breaks in the line current) Hope all this makes sense! One final tip, don't try to reset the lever of the 43 tester when it's energized (IE if the phone's off hook or disconnected), it'll fight back! (done that a few times!) Attached Thumbnails