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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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26th Feb 2021, 5:57 pm | #1 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
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RADAR IF Strip?
Hi folks.
A little project to keep me busy. This looks like an if strip from an aircraft radar receiver set. R.U. Type 196. Ser. no. 0198. ref. no. 10DB/6862 It has ten valves:- 1 X CV147 - EC90 i/p cathode follower. 7 X CV 138 - EF91 if amps. 1 X CV140 - EB91 Det. 1 X CV138 - EF91 o/p amp. All the decoupling caps were leaky, some almost short cct. All res. were out of tol. most of the rf chokes were o/c. It seems to require 160v at 160 ma for ht, 6.3 heaters, approx 3 to 4v neg for agc. ( I built a high voltage power supply to work this thing) The if transformers seem to tune at about 44mHz 50dB above 1 uv cw This gives an o/p of about 2v neg pulse every 10 m/s I have'nt drawn out the cct yet. Could give me more clues when I have done this. The power i/p connector is an 8 pin in line jones plug. The signal plugs are some kind of co-ax connectors. Back in the 60's I worked on testing naval radar receivers and displays which gave me a clue as to what this is Is there anyone out there that can remember testing this type of kit from the 50's (estimated). And can throw some more light on this? John. |
26th Feb 2021, 6:18 pm | #2 |
Heptode
Join Date: Sep 2009
Location: Tonbridge, Kent, UK.
Posts: 687
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Re: RADAR IF Strip?
Picture? Part number?
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26th Feb 2021, 8:13 pm | #3 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: RADAR IF Strip?
This would appear to be part of ASV Mk15 radar, covered by A.P.2544H, but I don't have any further detail.
Some pictures would be very interesting. Andy |
27th Feb 2021, 4:35 pm | #4 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
|
Re: RADAR IF Strip?
Pics as requested
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27th Feb 2021, 4:42 pm | #5 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
|
Re: RADAR IF Strip?
further pics of if strip.
If anyone has a 6 way in line jones socket or coax sockets to fit this strip I would like to purchase them. I will now spend several days drawing out the circuit, I will post it when finished. John. |
12th Mar 2021, 4:55 pm | #6 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
|
Re: RADAR IF Strip?
Here it is.
The cct of the if strip. It seems that the if freqquency of the wartime if's is 45Mcs, so I will now go back on the bench and do more detailed testing. Don't know what I am going to do with it once that I have proved that it is working condition. It has been a good project, ok if you have got a lot of time to spare. If anyone has any comments or test idea's please feel free. john. |
12th Mar 2021, 6:21 pm | #7 |
Nonode
Join Date: Jun 2009
Location: Herefordshire, UK.
Posts: 2,495
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Re: RADAR IF Strip?
A couple of suggestions:
1) Can you measure the IF strip's bandwidth? 2) Try a 45 Mc/s dipole aerial as input and connect higher impedance headphones via a capacitor (for DC isolation) to the output and listen... |
12th Mar 2021, 6:49 pm | #8 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
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Re: RADAR IF Strip?
Thanks Steve.
When I can get the workshop warm enough to work in I will post the results. John. |
18th Mar 2021, 5:32 pm | #9 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
|
Re: RADAR IF Strip?
Hi.
A bit more detail. The 10ms pulse was caused by me connecting part of the agc line to the 6.3 heater line, now corrected. The center frequency that the if's tune to is 44mHz, the -3dB points are 43.7mHz and 44.7mHz giving a 1mHz bandwidth. The modulation bandwidth is 5Hz to 25kHz at -3dB ( good hi fi eh wat) I get the best results with the agc set to -3v. The first 4 valve grid 3 connections to the socket marked Y with the 470k to chassis does nothing if I earth it. Any suggestions? I suppose I could build a front end and listen to some moonbounce experiments. John. |
18th Mar 2021, 6:15 pm | #10 |
Nonode
Join Date: Jun 2009
Location: Herefordshire, UK.
Posts: 2,495
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Re: RADAR IF Strip?
theredhouseinn,
I had been wondering whether you might pick up the Amplitude Modulated pulses of this radar: http://mst.nerc.ac.uk/nerc_mst_radar.html It is possible the signal (ie the back-scattered, not the direct path) would be strong enough to make it through your IF passband. I like the Moonbounce suggestion! |
30th Mar 2021, 11:56 am | #11 |
Hexode
Join Date: Jul 2006
Location: Sheffield, South Yorkshire, UK.
Posts: 312
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Re: RADAR IF Strip?
I didn't know about the NERC radar, very interesting. Should be able to hear that via ionospheric scattering, meteor trails, etc. I'll have a listen for it if I can find a suitable antenna.
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