A possible PYE 45 Mc/s radar IF strip - UK Vintage Radio Repair and Restoration Discussion Forum

SteveCG · 5th Mar 2021, 11:38 am

I've a possible PYE If strip - somewhat modified by others; home-built TV? I've tried looking for circuit diagram information on what it might have originally been.

It has an identity number painted on it 10DB/84.65, and comprises 5 VR91's and what was, but is no longer present, a small valve diode detector. The best I've achieved so far is a Practical Television article, March 1952, Page 436. However the info there is incomplete. The article talks about an R.A.F. unit no. 153.

Ideally I'd like the original circuit diagram and knowledge on how it was originally controlled in terms of voltages and signals applied to it. Can anybody point me in the right direction?

I know that these valves were extensively used in Second World War Radars and that there were IF strips of differing types that used them.

M0FYA Andy · 5th Mar 2021, 10:50 pm

Receiving Unit Type 153 has Stores Reference Number 10DB/6097, your unit with Ref No 10DB/8465 is a Receiving Unit Type 153A.
I'm trying to ascertain the difference, probably not very much.

Andy

M0FYA Andy · 6th Mar 2021, 12:11 pm

Here is the circuit of the Receiving Unit Type 153, I'm still looking for information on the Type 153A but I'll be surprised if there is much change.

I'd be very interested in some photos of your unit, please, including the Stores Reference Number.

Andy

M0FYA Andy · 6th Mar 2021, 12:47 pm

OK, here is the circuit of the 153A. Used in H2S MkIVA.

andy

geeoboeh2s · 6th Mar 2021, 12:48 pm

Receiving unit type 153 led to a number of very similar units used by all three armed services and with different part numbers and stores numbers. Some had very minor differences but were still allocated a different part number even if only from a different manufacturer.
You say that yours has 5 VR91s and is missing the VR92 diode. The five VR91s are the bandpass ampifier stages. There should also be a sixth VR91 the other side of the VR92 cover. This is a video amplifier. You made no reference to a further mssing valve so has the socket been removed.
Andy has requested a picture that should help with identification.

Chris

HamishBoxer · 6th Mar 2021, 2:33 pm

Yes, the 45mc/s IF strips were used in homemade 50's television. Very often with a green CRT.

SteveCG · 6th Mar 2021, 6:38 pm

Here are some 'photos as requested.

M0FYA Andy · 7th Mar 2021, 11:32 am

Is there evidence that the chassis has been shortened at the right-hand end in your first picture?

Andy

SteveCG · 7th Mar 2021, 11:50 am

I've attached a photo of the end, where on very close examination I reckon the final VR91 stage has been cut off. Who ever did it did quite a good job. The modifications that I've discovered so far are:

1) The two input Pye connectors replaced by a single Belling & Lee Socket;

2) The original 8 pin Jones plug replaced with a 6 pin Jones plug. This only uses 5 out of the six pins;

3) The removal of the original pin 5, 6 circuitry and its replacement with a -5 volt line derived from the heater circuit;

4) The replacement of the VR92 valve diode in the little shielded box with a semiconductor diode. By the way, the modifications list on the box has no entries.

So all in all, a little hacked about...

SteveCG · 8th Mar 2021, 6:30 pm

An update:

The input circuitry has been slightly modified; the 82 and 270 Ohm resistors have been removed.
The output circuit is simply the output end of L16 (see the 153A .pdf above).

A correction to item no.5 of my list above, the voltage should read -1.5 Volts.

Anyway, it works. I can receive the pulses of an Ionospheric Radar system which operates on 46.4 Mc/s. Rather appropriate, a radar IF strip receiving radar signals...

Thank you MOFYA_Andy for your help.

Julesomega · 9th Mar 2021, 12:39 pm

Quote:

Originally Posted by SteveCG

Anyway, it works. I can receive the pulses of an Ionospheric Radar system which operates on 46.4 Mc/s. Rather appropriate, a radar IF strip receiving radar signals....

How very fitting!

My friend in Germany reckons that would be the Belgian BRAMS radar, Yper & Dourbes on 49.97, 150W brams.aeronomy.be

He once heard 46.3MHz, radar PRF=25 Hz, with tone beep, Es dir=East

Julesomega · 9th Mar 2021, 12:55 pm

Sorry, having looked through the BRAMS pages I see that it is a CW system, which leaves an interesting question about the pulsed emissions. He only once heard pulses on 46.3, radar PRF=25 Hz, with tone beep, dir=East during Sporadic E conditions, which certainly have not occurred this week.
My friend has one of the best all-band receiving installations in Europe but says he has never heard anything of the HAARP High-frequency_Active_Auroral_Research_Program from Alaska, which uses 49MHz among others.

dx.3sdesign.de/

I think you must have a local source

SteveCG · 9th Mar 2021, 7:17 pm

Julesomega,

I would not be surprised if it was localish - it is strong. I've received it on Band I DX TV, just below the old channel E2 vision frequency, for a few years now. I re-confirmed the 46.4 Mc/s frequency with a separate radio today. It is not CW, rather a sequence pattern of regular pulses with non regular ones.

5th Mar 2021, 11:38 am	#1
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	A possible PYE 45 Mc/s radar IF strip I've a possible PYE If strip - somewhat modified by others; home-built TV? I've tried looking for circuit diagram information on what it might have originally been. It has an identity number painted on it 10DB/84.65, and comprises 5 VR91's and what was, but is no longer present, a small valve diode detector. The best I've achieved so far is a Practical Television article, March 1952, Page 436. However the info there is incomplete. The article talks about an R.A.F. unit no. 153. Ideally I'd like the original circuit diagram and knowledge on how it was originally controlled in terms of voltages and signals applied to it. Can anybody point me in the right direction? I know that these valves were extensively used in Second World War Radars and that there were IF strips of differing types that used them.

5th Mar 2021, 10:50 pm	#2
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: A possible PYE 45 Mc/s radar IF strip Receiving Unit Type 153 has Stores Reference Number 10DB/6097, your unit with Ref No 10DB/8465 is a Receiving Unit Type 153A. I'm trying to ascertain the difference, probably not very much. Andy

6th Mar 2021, 12:48 pm	#5
geeoboeh2s Rest in Peace Join Date: Mar 2010 Location: Berkshire, UK. Posts: 72	Re: A possible PYE 45 Mc/s radar IF strip Receiving unit type 153 led to a number of very similar units used by all three armed services and with different part numbers and stores numbers. Some had very minor differences but were still allocated a different part number even if only from a different manufacturer. You say that yours has 5 VR91s and is missing the VR92 diode. The five VR91s are the bandpass ampifier stages. There should also be a sixth VR91 the other side of the VR92 cover. This is a video amplifier. You made no reference to a further mssing valve so has the socket been removed. Andy has requested a picture that should help with identification. Chris

6th Mar 2021, 2:33 pm	#6
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: A possible PYE 45 Mc/s radar IF strip Yes, the 45mc/s IF strips were used in homemade 50's television. Very often with a green CRT. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

6th Mar 2021, 6:38 pm	#7
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: A possible PYE 45 Mc/s radar IF strip Here are some 'photos as requested. Attached Thumbnails

7th Mar 2021, 11:32 am	#8
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: A possible PYE 45 Mc/s radar IF strip Is there evidence that the chassis has been shortened at the right-hand end in your first picture? Andy

7th Mar 2021, 11:50 am	#9
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: A possible PYE 45 Mc/s radar IF strip I've attached a photo of the end, where on very close examination I reckon the final VR91 stage has been cut off. Who ever did it did quite a good job. The modifications that I've discovered so far are: 1) The two input Pye connectors replaced by a single Belling & Lee Socket; 2) The original 8 pin Jones plug replaced with a 6 pin Jones plug. This only uses 5 out of the six pins; 3) The removal of the original pin 5, 6 circuitry and its replacement with a -5 volt line derived from the heater circuit; 4) The replacement of the VR92 valve diode in the little shielded box with a semiconductor diode. By the way, the modifications list on the box has no entries. So all in all, a little hacked about... Attached Thumbnails

8th Mar 2021, 6:30 pm	#10
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: A possible PYE 45 Mc/s radar IF strip An update: The input circuitry has been slightly modified; the 82 and 270 Ohm resistors have been removed. The output circuit is simply the output end of L16 (see the 153A .pdf above). A correction to item no.5 of my list above, the voltage should read -1.5 Volts. Anyway, it works. I can receive the pulses of an Ionospheric Radar system which operates on 46.4 Mc/s. Rather appropriate, a radar IF strip receiving radar signals... Thank you MOFYA_Andy for your help.

9th Mar 2021, 12:55 pm	#12
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,103	Re: A possible PYE 45 Mc/s radar IF strip Sorry, having looked through the BRAMS pages I see that it is a CW system, which leaves an interesting question about the pulsed emissions. He only once heard pulses on 46.3, radar PRF=25 Hz, with tone beep, dir=East during Sporadic E conditions, which certainly have not occurred this week. My friend has one of the best all-band receiving installations in Europe but says he has never heard anything of the HAARP High-frequency_Active_Auroral_Research_Program from Alaska, which uses 49MHz among others. dx.3sdesign.de/ I think you must have a local source __________________ - Julian It's good here

9th Mar 2021, 7:17 pm	#13
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: A possible PYE 45 Mc/s radar IF strip Julesomega, I would not be surprised if it was localish - it is strong. I've received it on Band I DX TV, just below the old channel E2 vision frequency, for a few years now. I re-confirmed the 46.4 Mc/s frequency with a separate radio today. It is not CW, rather a sequence pattern of regular pulses with non regular ones.