Air Ministry IF unit 10U/254 - UK Vintage Radio Repair and Restoration Discussion Forum

SteveCG · 18th Mar 2021, 10:21 am

I've tried searching for information on this IF unit. The best I have been able to do is to work out that 10U/254 is likely to be an Air Ministry Stores Reference number. How to find out the designation of the Receiver that incorporates the IF Unit has eluded me. Does 10U mean a Radio IF unit whereas a 10UB would indicate a radar IF Unit??

Photos attached.

theredhouseinn · 18th Mar 2021, 11:51 am

Hi Steve.
I am having the same trouble finding info on my if unit RU196.
Have a look at my post - "RADAR IF Unit"
John.

M0FYA Andy · 18th Mar 2021, 4:51 pm

John,
I've already told you that your unit is part of ASV Mk15 radar, covered by A.P.2544H.

I'm struggling with 10U/254.

Andy

geeoboeh2s · 19th Mar 2021, 1:24 pm

It is IF amplifier from ther TR19xx range of RAF/commercial transceivers.
STC designation STR.9-x
I think the frequency is 9.72MHz.

Chris

SteveCG · 19th Mar 2021, 6:35 pm

Thank you geeoboeh2s for the info.

A search for TR1985 (mentioned on the vmarsmanuals web-site) produced this link:

http://www.radiomuseum.co.uk/str9x.pdf

So my thanks to radiomuseum as well.

AdrianH · 19th Mar 2021, 7:05 pm

Chris is spot on.

The military version of this unit has a different layout, well mine has anyway with two tuning caps per IF stage at the top of the board and a different valve line up in the latter stages.

So the STC STR9.x manuals which are online will match that particular IF, here is a pic from the pdf.

Click image for larger version

Name: ifamp.png
Views: 78
Size: 159.4 KB
ID: 229592

Adrian

SteveCG · 20th Mar 2021, 11:12 am

AdrianH,

Indeed, the IF unit in the STC manuals .pdf fits the one I have, as per your pic.

One thing of note is that the input socket has 250 Volts HT on it! (providing the Anode load for the front end stage valve notated as 3V4).

SteveCG · 5th Apr 2021, 12:14 pm

Just to wind up this thread. The unit worked without any problem and as advertised!

18th Mar 2021, 10:21 am	#1
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Air Ministry IF unit 10U/254 I've tried searching for information on this IF unit. The best I have been able to do is to work out that 10U/254 is likely to be an Air Ministry Stores Reference number. How to find out the designation of the Receiver that incorporates the IF Unit has eluded me. Does 10U mean a Radio IF unit whereas a 10UB would indicate a radar IF Unit?? Photos attached. Attached Thumbnails

18th Mar 2021, 11:51 am	#2
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: Air Ministry IF unit 10U/254 Hi Steve. I am having the same trouble finding info on my if unit RU196. Have a look at my post - "RADAR IF Unit" John.

18th Mar 2021, 4:51 pm	#3
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: Air Ministry IF unit 10U/254 John, I've already told you that your unit is part of ASV Mk15 radar, covered by A.P.2544H. I'm struggling with 10U/254. Andy

19th Mar 2021, 1:24 pm	#4
geeoboeh2s Rest in Peace Join Date: Mar 2010 Location: Berkshire, UK. Posts: 72	Re: Air Ministry IF unit 10U/254 It is IF amplifier from ther TR19xx range of RAF/commercial transceivers. STC designation STR.9-x I think the frequency is 9.72MHz. Chris

19th Mar 2021, 6:35 pm	#5
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Air Ministry IF unit 10U/254 Thank you geeoboeh2s for the info. A search for TR1985 (mentioned on the vmarsmanuals web-site) produced this link: http://www.radiomuseum.co.uk/str9x.pdf So my thanks to radiomuseum as well.

19th Mar 2021, 7:05 pm	#6
AdrianH Octode Join Date: Mar 2020 Location: Blackburn with Darwen, Lancashire, UK. Posts: 1,572	Re: Air Ministry IF unit 10U/254 Chris is spot on. The military version of this unit has a different layout, well mine has anyway with two tuning caps per IF stage at the top of the board and a different valve line up in the latter stages. So the STC STR9.x manuals which are online will match that particular IF, here is a pic from the pdf. Adrian __________________ Asking questions and learning, or trying to! Youtube EF91Valve

20th Mar 2021, 11:12 am	#7
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Air Ministry IF unit 10U/254 AdrianH, Indeed, the IF unit in the STC manuals .pdf fits the one I have, as per your pic. One thing of note is that the input socket has 250 Volts HT on it! (providing the Anode load for the front end stage valve notated as 3V4).

5th Apr 2021, 12:14 pm	#8
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Air Ministry IF unit 10U/254 Just to wind up this thread. The unit worked without any problem and as advertised!