Author Topic: GPO 722 (aka the TRIMPHONE!)  (Read 16292 times)

Offline gpo706

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #45 on: November 02, 2011, 08:53:30 PM »
"now this should take five minutes, where's me screwdriver went now..?"

Offline GG

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #46 on: November 03, 2011, 03:53:23 AM »


Cool, thanks for posting that.  I have an old two-tone green one with a USA modular cord on it, that could be converted back.  Yes you're right, they chose odd colors of green for those, compared to 706 greens.  Mine's gone just a little yellow-ish, could probably use the Retrobright treatment.  (Also recently picked up a Snowdon version, green/white, perfect condition except the dial needs a little work, which I can do because I've got plenty of GPO parts.)

The way I deal with slidey phones is by parking them on furry mousepads.  The cloth-like top surface keeps the phone feet in one place, and the non-skid bottom surface prevents the whole thing sliding around.  Use plain gray mousepads with no distracting graphics or annoying adverts on them; these are easy to find in most computer places. 

Offline gpo706

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #47 on: November 03, 2011, 07:29:13 PM »
Or blutac as related above, if you don't mind the feet coming off!

This is the only supplier I have found re-makes the right cordage, he must do it in small batches, sells, then his leads vanish till he gets some more done, worth adding to your ebay sellers lists and looking in.
"now this should take five minutes, where's me screwdriver went now..?"

Offline GG

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #48 on: November 04, 2011, 12:58:06 PM »


I should probably order 2 or 3 of these right now, one for my 2-tone green 722, and the other to hold as a spare for when I score a DTMF version just in case.  Yes the decadic pulse version is kinda' cute too, with ten buttons.... hmm...

Offline Stephen Furley

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #49 on: November 07, 2011, 08:33:49 PM »
Has anybody noticed anything strange about the No. 30 dial used in the Trimphone?  There were many different dials used by the GPO, but almost all of them have the 0 at the bottom, and the fingerstop close to it.  The No. 30 dial has the 9 at the bottom.  I only noticed this last week.  If we ignore the very early dials, the special ones for payphones, emergency only service, test equipment, and a few little-used dials, such as the GEC No. 51, the small-size No. 17 for the engineer's telephone 280 etc. then there were only four main dial types from the 150 candlestick to the end of the dial era.  These were Nos. 10, 12, 21 and 54a.  These are all quite similar, the No. 10 used a different means to stop the dial from pulsing when being pulled round (the 'Slipping cam' mechanism),while the others used the 'trigger' mechanism, but otherwise the main difference from 12 to 21 to 54a was increased use of plastic, reduced cost and reduced weight.  When I removed the fingerwheel from my Trimphone recently to clean underneath it I noticed that while it's generally similar to the 54a, with a similar plastic central hub on which the fingerwheel mounts, on the 'normal' dials the pin which engages with the fingerwheel is directly below the central screw hole (or both above and below in the case of the 54a) on the No. 30 it's at about the 5 o'clock position.  Only then did I realise that the whole dial is rotated by one hole position, and obviously, the numbers have to be printed differently on the dial plate to keep them upright when the dial is mounted in this slightly rotated position.  This means that a standard 21 of 54a dial cannot be used in a Trimphone.

The No. 30 dial is clearly shown here:

http://www.britishtelephones.com/dial1.htm#d30

Note that while the left picture shows the dial in its correct position, the centre one, which shows the radioactive gas tube, is incorrect, and shows it in the same position as a normal dial.  Odd that I've never noticed this before.  I don't know the reason.

Offline GG

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #50 on: November 08, 2011, 05:49:54 AM »


I noticed it first time I saw a Trimphone, which was ITT's "Deltaphone" that was briefly sold at Radio Snack in the late 70s. 

The way I think of those dial positions is: zero at the 4:00 position is "Western Electric," and zero at the 6:00 position is "Automatic Electric."  GPO telephones always had zero at 6:00, but the Deltaphone / Trimphone had zero at 5:00 which was closer to "Western Electric."  Aside from that, all the mechanical bits are the same between a Trimphone dial and any other GPO trigger dial. 

I figured the reason GPO rotated the dial slightly, was to avoid the situation where the fingerstop would be too close to the rest position of the handset.  This, to allow more room to get one's fingers under the handset to pick it up, without getting a fingernail caught under the fingerstop and thereby either bouncing the phone on the table or breaking a long fingernail (primarily women; they wouldn't have wanted to anger half their clientele). 

Very clever adaptation, and nice of them to have done it despite the added cost for the different style number plates for those dials. 

Some other European telephones (Germany, Poland, Dutch Heemaf, Czech, some USSR), use the same dial position as the Trimphone, on their conventional desk sets.   Others (Ericsson, France PTT, Austria, Yugoslavia, some USSR) use the dial position with 0 at 6:00. 

Someone here recently explained the somewhat counterintuitive (to us USA-ers) GPO practice of having the housing screws in the cradle on the 706 and at the rear on the 746: so that the telephone wouldn't have to be turned upside-down on the table, where it might scratch a polished tabletop.  Seen in that light, it's also a very clever adaptation and makes plenty of sense.  (Presumably the USA practice of holding an upside-down phone between one's knees whilst unscrewing the base, would have been seen as vaguely rude or vulgar in the UK, therefore not done that way.)

Offline Owain

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #51 on: November 08, 2011, 06:12:28 AM »
I figured the reason GPO rotated the dial slightly, was to avoid the situation where the fingerstop would be too close to the rest position of the handset.  This, to allow more room to get one's fingers under the handset to pick it up, without getting a fingernail caught under the fingerstop and thereby either bouncing the phone on the table or breaking a long fingernail (primarily women; they wouldn't have wanted to anger half their clientele).  ...

Someone here recently explained the somewhat counterintuitive (to us USA-ers) GPO practice of having the housing screws in the cradle on the 706 and at the rear on the 746: so that the telephone wouldn't have to be turned upside-down on the table, where it might scratch a polished tabletop.  Seen in that light, it's also a very clever adaptation and makes plenty of sense.  (Presumably the USA practice of holding an upside-down phone between one's knees whilst unscrewing the base, would have been seen as vaguely rude or vulgar in the UK, therefore not done that way.)

I thought the Trimphone dial was smaller, but the holes are the same size. Therefore they will take up a greater proprortion of the circumference of the dial. Either the 1 has to be rotated right, or the 0 has to be rotated beyond 6 o'clock. I think rotating the 1 right would have caused more problems.

Turning phones upside down was avoided because it disturbed dust inside the phone. Also British phones of the 706 later had a little tag so that the hookswitch could be latched on-hook without the cover and handset being in place, for testing purposes and to avoid engaging the line. The latch could be disengaged from outside the phone after the cover had been replaced.

They really did put a lot of thought into designing stuff in those days.

Offline Stephen Furley

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #52 on: November 08, 2011, 09:14:36 AM »
Quote
I thought the Trimphone dial was smaller, but the holes are the same size. Therefore they will take up a greater proprortion of the circumference of the dial. Either the 1 has to be rotated right, or the 0 has to be rotated beyond 6 o'clock. I think rotating the 1 right would have caused more problems.

The fingerwheel and dial plate, or fingerplate and dial label to use GPO terminology, of the No. 30 dial are the same diameter as those on the No. 54a; the size and pitch circle diameter of the finger holes is also the same.  It's not like the WE dials, where the holes do occupy a greater angle of a smaller wheel.  I read somewhere that the body diameter of the No. 30 dial is actually slightly greater than that of the standard dials to accomodate the gas tube, but I haven't actually measured it.  For anybody not familiar with them, the body diameter of standard GPO dials is considerably smaller than the fingerwheel diameter.   The only smaller dials which I'm aware of, at least since the introduction of the No. 10 are the No. 17 which fits into the back of the receiver compartment on the 280 telephone, and the moving finger stop type as used on the Contempra.

Offline Stephen Furley

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #53 on: November 08, 2011, 09:22:40 AM »
Quote
Someone here recently explained the somewhat counterintuitive (to us USA-ers) GPO practice of having the housing screws in the cradle on the 706 and at the rear on the 746: so that the telephone wouldn't have to be turned upside-down on the table, where it might scratch a polished tabletop.  Seen in that light, it's also a very clever adaptation and makes plenty of sense.

A clever adaptation possibly, but certainly not a new one; I think the 746 was introduced in 1966, and my recently-acquired Leich 105, from 1955 has the same arrangement, as do my older Leich 615, SC 1543 and I think one or two others.

Offline JubileeCompact

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #54 on: November 17, 2011, 05:53:19 PM »
From GPO 706......

KIT 422A - WALL MOUNTING KIT
This consists of a plastic wedge shaped box (wall bracket), handset clip, cradle bar and a longer case retaining screw. To install, fit the bracket to the wall using the three securing holes.
The following modifications will have to be carried out to the telephone instrument:-

   1. Remove the four rubber feet on the underside of the instrument.
   2. Remove the existing line cord. The exchange line is then connected to the instrument via the hard wiring.
   3. The existing cradle bar may need to be replaced if it differs from the new cradle bar found in the Kit 422A. The exchange line cable should be brought into the wall bracket via the bottom, under the sloped back panel that contains the fitting instructions and behind the cable retainer which is situated as part of the top right-hand telephone support hook.

Once the cable has been routed as described the cable should be cut to length i.e. to the bottom edge of the wall bracket. Then strip the outer sheathing to approximately 50 mm below the support hook. Hang the instrument on the two support hooks of the wall bracket and clip the lower half into place to secure. Terminate the exchange line cable. Replace the telephone cover and place the handset clip in position then secure by using the longer case retaining screw."

On the link above, I have never seen one EVER!

Here ya go...... :)
Seamus

Offline gpo706

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #55 on: November 18, 2011, 07:18:23 PM »
So you got one JC?

Thanks for the picture, at least I can say I've seen one now!

"now this should take five minutes, where's me screwdriver went now..?"

Offline JubileeCompact

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #56 on: November 21, 2011, 01:41:30 AM »
Hey 706...

Yup it came from the Bay about a year ago. As you can see its missing the longer case screw so cant really be used but I will attempt to do a pic of a converted unit at some point :). And its the only one Ive ever seen as well- guessing it wasnt a popular option!!

Seamus
Seamus

Offline Owain

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #57 on: September 28, 2017, 03:32:40 PM »
"KIT 422A - WALL MOUNTING KIT
This consists of a plastic wedge shaped box (wall bracket), handset clip, cradle bar and a longer case retaining screw. ...
On the link above, I have never seen one EVER!

Ladies and gentlemen, I proudly present ...

www.ebay.co.uk/itm/122727555046

849 !

It is a new unissued trimphone from 1978 fitted with a wall mounting kit 422A. This wall mounting kit was made in such small numbers most telephone collectors or dealers have never seen one.

« Last Edit: September 28, 2017, 08:24:30 PM by WEBellSystemChristian »

Offline twocvbloke

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #58 on: September 28, 2017, 05:39:03 PM »
Intriguing looking setup there, it'd be interesting to see how it works with inserting the handset into that cup thing, but at that price, yeah, bit too high for my books... :)

Offline ThePillenwerfer

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Re: GPO 722 (aka the TRIMPHONE!)
« Reply #59 on: September 28, 2017, 06:10:13 PM »
That's something I'd never even heard of, never mind seen.