Author Topic: Help!- Heefmaf PPT Dialing Pops and Ringing Problems  (Read 3791 times)

Offline countryman

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Re: Help!- Heemaf PTT 1955 Dialing Pops and Ringing Problems
« Reply #30 on: July 13, 2019, 04:06:33 PM »
My Heemaf from this thread arrived.
It also pops POPS! like described in the original post. It has no diode limiter. For a test I connected a limiter from a german phone of the same age, with almost the same wiring setup. Pop is gone.
I measured a limiting voltage of 0.4 V with my multimeter, so it would be more like 2 germanium or schottky diodes than like usual silicon diodes (0.7 V).  *)
The phone has an efficient receiver element with a loud and clear sound. My guess is the problem with popping noise from switches became urgent with this generation of receiver elements.
The phone has Philips logos on the plungers and no PTT marks. It should be an export version. I'm not going to venture about it's provenience any more, considering the reverse dial. According to the seller the previous owner was a (german) employee of the U.S. army signal corps at the Heidelberg base.

The phone cleaned up nicely, no damages, everything seemed untouched and original. Once again my well tried plastics cleaner had to cut through a daunting layer of cigarette tar.  The moldy look of the auction picture is gone now and the phone has a matt finish. It almost looks like it was made this way, but under the handset and on the inside it is shiny. I think it would polish up nicely, but I'll preserve the look for now.
I also guess I could replace the number ring with a normal 1...0 Siemens&Halske part (the dial is a clone of the german S&H N38), but it's not too bad to use like it is as the 0 and the 5 are in the right place. Swedish 012..9 dials are worse.

My phone rings nicely on my VOIP router. Not overly loud, but nice. The router does not offer too much ringing power, some other phones won't ring reliably with it.

*) Edit: According to Wikipedia the gernman noise limiters were made of selenium diodes.
« Last Edit: July 14, 2019, 05:09:30 AM by countryman »

Offline twocvbloke

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Re: Help!- Heefmaf PPT Dialing Pops and Ringing Problems
« Reply #31 on: July 14, 2019, 11:29:07 AM »
With that matte finish, it could be considered as a stealth communications telephone... ;D

Offline rdelius

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Re: Help!- Heefmaf PPT Dialing Pops and Ringing Problems
« Reply #32 on: July 14, 2019, 11:42:33 AM »
It appears that the dial has the Heemaf logo.It is possible that just the number plate was switched.

Offline countryman

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Re: Help!- Heefmaf PPT Dialing Pops and Ringing Problems
« Reply #33 on: July 14, 2019, 12:52:22 PM »
In fact the dial is a Heemaf. That all looked very much original.

It had a sticker "No classified matter will be discussed over this phone" on it. It was easily removable for cleaning. I preserved the sticker and could reattach it.

Offline RB

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Re: Help!- Heefmaf PPT Dialing Pops and Ringing Problems
« Reply #34 on: August 07, 2019, 05:21:04 PM »
Don't know if this has been solved yet, but as a side note, the hook switches look much like the switch blades used in EM pinball machines, something I am very familier with.
the blades can get bent, and if this is the case here, it would change the open/close order.
I have hurd on here if the order is reversed, you get pops.
just a thot.  ;)

Offline dsk

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Re: Help!- Heefmaf PPT Dialing Pops and Ringing Problems
« Reply #35 on: August 08, 2019, 04:31:19 AM »
dsk, would you please give your opinion of why receiver clicks (when hanging up and when dialing) and ring tap were not considered a problem.

Also, why low impedance ringers continued to be used in Europe long after they were discontinued here. In your country, did they wire extension ringers in series with the main station? Were even modern ringers low impedance? What about currently produced phones with electronic ringers---how does the REN compare with the REN of North American electronic ringers?

A little more about this, of course it was a way of using less money, you did often just dial without hving the receiver close to your ears, and it would usually take time to get the dial tone, it took time to get the ringing etc.  Moat phones here had a circuit pretty close to WE 306 when I grew up. 

In 1967 a new generation phones came, still rotary, but electronic ringer, and transistorazed with dynamic transmitter element:  [size=78%]

This was also the first where we could adjust the ringer volume.  (The ringer has a terrible sound)

More here:
This was the first with diades across the receiver, and I have measured the REN load The impedance was depending on the volume and went from approx 6300 to 41000 ohms or 1.1 REN to 0.17 REN

The later touch tone phones (1982....) have I never tried to measure the REN load on.   ;)

« Last Edit: August 08, 2019, 04:53:11 AM by dsk »