Relay Unit Type125. - UK Vintage Radio Repair and Restoration Discussion Forum

gm0ekm cecil · 23rd Mar 2023, 6:13 pm

Anyone familiar with this relay type 125. I would be interested to know if it was from WWII or the Cold War era. I presume it was an aircraft installation.

trh01uk · 23rd Mar 2023, 6:34 pm

Cecil,

I've had these relay units in my hands in the past - don't think I have any now.

The clue to its age is in the AP1086 code number. "10F/16827". My understanding is that codes beyond 10,000 are generally post WWII. So I will plump for Cold War era.

I looked up this Relay Type 125 in my copy of AP1086, and its listed in the 1950 edition that I have. Its description is as follows:

"Aerial changeover relay for changing over from Transmitter to Receiver in VHF T.R.s. 24 volt supply."

So the type of equipment I'm thinking it is part of is TR.1934, TR.1935, TR.1936 series. A set of VHF transceivers covering 100 - 156Mc/s. And these are definitely post-war.

Richard

lesmw0sec · 23rd Mar 2023, 6:40 pm

I agree with Richard, purely because the main RF connector in use during WW2 was the Pye plug/socket.

trh01uk · 23rd Mar 2023, 6:43 pm

Cecil,

as far as I recall, there is a fairly nice coaxial relay inside the box. Not sure what impedance the system is - the TR.1935 series list a 45 ohm impedance on the transmit side.....

Richard

gm0ekm cecil · 23rd Mar 2023, 6:46 pm

Thanks Richard, I appreciate your quick reply. This relay which I had no info, was in my former radio communications museum and has been in the junk box for a few years.
Regards Cecil.

M0FYA Andy · 23rd Mar 2023, 6:58 pm

I believe this relay was used in the Canberra, and probably in numerous other aircraft from that era.

Andy

G6Tanuki · 23rd Mar 2023, 7:03 pm

Yes the "SO239" sockets [sometimes called 'UHF'] date it somewhat post-WWII; they were generally considered to be 'around 50 Ohms' but being not much more than a screened banana-plug they really didn't count as UHF-capable though were often used up to a couple of hundred MHz.

Nickthedentist · 23rd Mar 2023, 8:05 pm

Also used in 1980s CBs??

barrymagrec · 23rd Mar 2023, 8:27 pm

Older CCTV kit as well.

gm0ekm cecil · 25th Mar 2023, 12:20 pm

Many thanks for all the replies.
Cecil ~ GM0EKM.

23rd Mar 2023, 6:13 pm	#1
gm0ekm cecil Tetrode Join Date: Jan 2008 Location: Shetland, UK. Posts: 75	Relay Unit Type125. Anyone familiar with this relay type 125. I would be interested to know if it was from WWII or the Cold War era. I presume it was an aircraft installation. Attached Thumbnails

23rd Mar 2023, 6:34 pm	#2
trh01uk Octode Join Date: Nov 2010 Location: Ross-on-Wye, Herefordshire, UK. Posts: 1,530	Re: Relay Unit Type125. Cecil, I've had these relay units in my hands in the past - don't think I have any now. The clue to its age is in the AP1086 code number. "10F/16827". My understanding is that codes beyond 10,000 are generally post WWII. So I will plump for Cold War era. I looked up this Relay Type 125 in my copy of AP1086, and its listed in the 1950 edition that I have. Its description is as follows: "Aerial changeover relay for changing over from Transmitter to Receiver in VHF T.R.s. 24 volt supply." So the type of equipment I'm thinking it is part of is TR.1934, TR.1935, TR.1936 series. A set of VHF transceivers covering 100 - 156Mc/s. And these are definitely post-war. Richard

23rd Mar 2023, 6:40 pm	#3
lesmw0sec Octode Join Date: Jul 2009 Location: Carmel, Llannerchymedd, Anglesey, UK. Posts: 1,378	Re: Relay Unit Type125. I agree with Richard, purely because the main RF connector in use during WW2 was the Pye plug/socket.

23rd Mar 2023, 6:43 pm	#4
trh01uk Octode Join Date: Nov 2010 Location: Ross-on-Wye, Herefordshire, UK. Posts: 1,530	Re: Relay Unit Type125. Cecil, as far as I recall, there is a fairly nice coaxial relay inside the box. Not sure what impedance the system is - the TR.1935 series list a 45 ohm impedance on the transmit side..... Richard

23rd Mar 2023, 6:46 pm	#5
gm0ekm cecil Tetrode Join Date: Jan 2008 Location: Shetland, UK. Posts: 75	Re: Relay Unit Type125. Thanks Richard, I appreciate your quick reply. This relay which I had no info, was in my former radio communications museum and has been in the junk box for a few years. Regards Cecil.

23rd Mar 2023, 6:58 pm	#6
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,398	Re: Relay Unit Type125. I believe this relay was used in the Canberra, and probably in numerous other aircraft from that era. Andy

23rd Mar 2023, 7:03 pm	#7
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 12,561	Re: Relay Unit Type125. Yes the "SO239" sockets [sometimes called 'UHF'] date it somewhat post-WWII; they were generally considered to be 'around 50 Ohms' but being not much more than a screened banana-plug they really didn't count as UHF-capable though were often used up to a couple of hundred MHz. __________________ A Desilu production. Color by DeLuxe.

23rd Mar 2023, 8:05 pm	#8
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,200	Re: Relay Unit Type125. Also used in 1980s CBs??

23rd Mar 2023, 8:27 pm	#9
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,439	Re: Relay Unit Type125. Older CCTV kit as well.

25th Mar 2023, 12:20 pm	#10
gm0ekm cecil Tetrode Join Date: Jan 2008 Location: Shetland, UK. Posts: 75	Re: Relay Unit Type125. Many thanks for all the replies. Cecil ~ GM0EKM.