UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Amateur and Military Radio

Notices

Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

Closed Thread
 
Thread Tools
Old 5th Feb 2016, 6:18 pm   #1
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Mk. 123 spy set

Firstly, a very Happy New Year 2016 from Bonnie Scotland to all members, and apologies for my long absence from the site...The soldering iron is still hot, however!
I have a MK.123 'spy set', including the manual. I also have a somewhat illegible schematic for the Mk. 123 12V inverter (which I don't have). I have been unable to find any posts relating to this set, on this site. I would be most grateful if any member could let me know where I can download a better copy of the inverter schematic, and ideally a brief explanation as to how the relay(s) therein, functions. Thanks. André (GM3VLB/ex-5Z4KL)
3delta2lb is offline  
Old 5th Feb 2016, 6:26 pm   #2
Ian - G4JQT
Octode
 
Ian - G4JQT's Avatar
 
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,320
Default Re: Mk. 123 spy set

Have a look at the manuals section in The Vintage & Military Amateur Radio Society website, VMARS.org.uk if you haven't already.

The guys there will almost certainly be able to help you with a good cct diagram, even if it's not actually in the manuals section.

Ian
Ian - G4JQT is offline  
Old 5th Feb 2016, 7:16 pm   #3
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Mk. 123 spy set

Ian.

I can't remember whether we've discussed this set together in the past.

I have a reprint of the manual "TECHNICAL PUBLICATION No. 82" which does show the 12V invertor. Whether it's any better than your version I don't know.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 5th Feb 2016, 10:21 pm   #4
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Mk. 123 spy set

The invertor circuit is also shown in Wireless For The Warrior Volume 4 and it looks very clear to me.

I don't have a flat bed scanner so I'll photograph it tomorrow when there's a bit of natural light.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 5th Feb 2016, 11:09 pm   #5
JulietMike
Tetrode
 
JulietMike's Avatar
 
Join Date: Dec 2012
Location: Andover, Hampshire, UK.
Posts: 85
Default Re: Mk. 123 spy set

Does this help ?

John

Sorry, just noticed that is the mains power pack.
Attached Thumbnails
Click image for larger version

Name:	MK 123 Power Pack.jpg
Views:	481
Size:	80.7 KB
ID:	119597  

Last edited by JulietMike; 5th Feb 2016 at 11:14 pm. Reason: Error
JulietMike is offline  
Old 6th Feb 2016, 11:30 am   #6
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Mk. 123 spy set

Here you go.
Attached Thumbnails
Click image for larger version

Name:	IMG_6840.jpg
Views:	402
Size:	60.1 KB
ID:	119613  
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 18th Feb 2016, 10:50 pm   #7
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

Hello again Graham, long time no speak (I believe last time was re' a certain 'gentleman's criminal activity. The Welsh courts were somewhat lenient!!... it all dragged on and on).
My apologies for the delay in getting back to you re' the Mk 123. I do believe we did discuss it briefly at some point, though can't remember context, memory lets me down, advancing senility... A further example of that is I saw your name in relation to another set a few days ago but again can't recollect re' which set. I'm currently working on a 123, a couple of "Paraset" replicas and a "Sweetheart" Rx replica. I did photo-copy the sheet so it's in one of these files!
Right now, I'm trying to figure out the Tx/Rx switching in that inverter and I'm going crazy. I wonder if you know if the relay is one relay with TWO energising coils and two sets of changeover contacts, or two SEPARATE relays each with one pair of switch over contacts? I presume it is shown non-energised and in the TX position, prior to the battery being connected? Thanks Graham.
Thanks also to John and Ian G4JQT for their inputs.
Kind regards to everyone... André GM3VLB
3delta2lb is offline  
Old 19th Feb 2016, 12:16 am   #8
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,799
Default Re: Mk. 123 spy set

Hi Andre,

They did do things in strange ways...

By the usual nomenclature there is one relay, RL1, operating two change-over contact sets, -1 and -2.

The relay has two coils, which it needs in order to do anything useful. Contacts -2 changes the transformer tap (by rather a large ratio the drawing implies) which feeds the voltage doubler rectifier. Contact et -1 directs the rectified outcome to either B2 or C2 on the output socket.

If the relay is not energised, only the left coil could be used to pull it in, because C2 has no power on it. THere's no point in the relay if it can never be turned on.

Once the relay pulls in, the right coil has to be used to hold it in because the left coil has no power. I suspect contact set -1 ought to be make-before-break or else there is a nasty moment in transit as there is no power to either coil and the thing risks turning into a buzzer. Contact set -2, however, had better not be make-before-break or it will play hob with the inverter.

I think the HT on B2 is a lot bigger than that on C2. I wondered if the relay coils are different because of this, but no, R4 looks to be there to accommodate the voltage difference.


David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Old 19th Feb 2016, 9:55 am   #9
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Mk. 123 spy set

I've found another hand drawn circuit diagram "Rearranged for clarity" for the same PSU. It may be a week before I can copy it and post it here.

The relay is of the latching type ie it can be toggled to either position depending on which coil is activated.

A2 is LT to the TX and RX.
B2 is HT to the TX.
B4 is power to the relay during Receive. From Switch S1C
C1 is Ground.
C2 is HT to the RX.
C3 provides a bias voltage.
D2 is common.
D3 is power to the relay during Transmit. From switch S1C
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 19th Feb 2016, 10:10 am   #10
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,799
Default Re: Mk. 123 spy set

Latching... that explains a lot. The two coils are of opposite polarity, and when the relay goes across killing HT to TX or to RX, it also kills the coil current which moved it, saving power. The relay stays there until the T/R switch is thrown back, when the other coil is powered from the HT feed which is still on to move the relay back.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Old 19th Feb 2016, 9:52 pm   #11
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

4th attempt!!! I replied to Graham TWICE in detail and both times lost the lot. The second time as I was trying to "copy" just in case. I then typed a short explanation, but clicked on "Advanced" then decided didn't need that, went back to the "Quick Reply" and it was again lost!!. I must be doing something wrong. Will try again tomorrow when I've calmed down!... Kind regards André
(next time, I'll type in 'MSWord' first!)
3delta2lb is offline  
Old 19th Feb 2016, 9:54 pm   #12
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Mk. 123 spy set

When you log in tick the remember me box, then you won't be automatically logged out.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 19th Feb 2016, 9:58 pm   #13
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

p.s. I found that 'other' article Graham. It was your schematic for a solid state vibrator, dated 11/07/2009. I had put it in my "Paraset" file for future use. Could you confirm that this works without a centre-tapped transformer? I've tried all sorts of inverter circuits, with varying degrees of success/efficiency... am happy to try another! André GM3VLB
3delta2lb is offline  
Old 19th Feb 2016, 10:08 pm   #14
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

OK. I've just logged out and logged back in again and ticked... BHTW, my 'original' cct is that from "Wireless for the Warrior, Vol.4". I can't recall if I downloaded it from there or if someone sent me a copy, but when I've tried just recently, Vol.4 doesn't seem to be available/accessible. I only see the one link to the Mk123 manual. Page 17 says there is a Technical Publication No.95 for the inverter, but I can't see where that is. Any info much appreciated. André
3delta2lb is offline  
Old 19th Feb 2016, 11:16 pm   #15
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,192
Default Re: Mk. 123 spy set

I don't know whether you have the full MK123 Manual (Technical Publication No. 82), but in my edition the last two pages are devoted to a hand drawn circuit diagram of the invertor unit and a hand written description of its operation.

Unfortunately I won't be in a position to copy these for about a week.

Not sure whether my set has an invertor, but I'll check.

The content of WFTH Vol 4 has never been available online as far as I know.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now  
Old 21st Feb 2016, 11:20 am   #16
M0SOE_Bruce
Pentode
 
Join Date: May 2013
Location: Deal, Kent, UK.
Posts: 139
Default Re: Mk. 123 spy set

For reference here are photos of the inside of the inverter supply. The unit came with my MK123.
Attached Thumbnails
Click image for larger version

Name:	psu1.jpg
Views:	312
Size:	71.3 KB
ID:	120386   Click image for larger version

Name:	psu2.jpg
Views:	265
Size:	88.1 KB
ID:	120387   Click image for larger version

Name:	psu3.jpg
Views:	264
Size:	71.5 KB
ID:	120388   Click image for larger version

Name:	psu4.jpg
Views:	250
Size:	66.0 KB
ID:	120389   Click image for larger version

Name:	psu5.jpg
Views:	254
Size:	67.7 KB
ID:	120392  


Last edited by M0SOE_Bruce; 21st Feb 2016 at 11:27 am.
M0SOE_Bruce is offline  
Old 21st Feb 2016, 9:13 pm   #17
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

Hello and thanks to all those posting on this topic. Graham, you proved I had never read the manual as far as the back page!! I indeed have these last (three) pages. I overlapped two of them as suggested (and scanned and reduced and will try to attach). I think I may now be able to understand, maybe!
The next problem (if I was to try and replicate the inverter, would be to find a suitable relay, or preferably find someone who can suggest a less 'convoluted' method, whilst still retaining the ability to simply "plug in and go".
Let me try submitting these 3 pages for the benefit of others also. Kind regards. André (GM3VLB).
Attached Thumbnails
Click image for larger version

Name:	123V - Notes on Inverter003.jpg
Views:	230
Size:	63.7 KB
ID:	120431   Click image for larger version

Name:	PSU in Rx mode 001.jpg
Views:	309
Size:	54.2 KB
ID:	120432   Click image for larger version

Name:	INV & PSU schematics superimposed.jpg
Views:	295
Size:	87.3 KB
ID:	120433  
3delta2lb is offline  
Old 21st Feb 2016, 11:23 pm   #18
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,799
Default Re: Mk. 123 spy set

The last latching relays I used were made by SDS-Relais. You'll need a rather high voltage coil.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Old 24th Feb 2016, 11:59 pm   #19
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

Sorry for further delay in commenting... seem to have too many other things on the go at the moment! Thanks Bruce for the pics of the inverter, amazing what they were able to cram in back then.
Thanks info' re' relay David. I don't think I'll search for one. Would be interested to know of another method of connecting a 'near'-replica inverter, if I ever got round to knocking one up. I haven't given it any thought, though I feel better brains than mine must have deemed the solution used at the time to be the 'simplest', or at least one with no further switching other than the main RX/TX switch on the set itself.
3delta2lb is offline  
Old 2nd Mar 2016, 12:31 pm   #20
3delta2lb
Retired Dormant Member
 
Join Date: Jul 2008
Location: Kelso, Scottish Borders
Posts: 63
Default Re: Mk. 123 spy set

During a bout of insomnia, I suddenly began to wonder why it didn't occur to the boffins who designed that somewhat complex Mk 123V inverter PSU, that there already was an efficient supply IN the set, and all that was needed was a simple 12V to AC mains (110, 220, 240V or whatever), as was common with many amateur radio transceivers in the 60s/70s.
I see, for example, 12V/24V to 220V/50Hz at up to 150W inverters available at under a tenner (inc. P&P) advertised on a well-known internet site. Comments?
André, GM3VLB
3delta2lb is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 11:55 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.