Radar Home page
Home page
  Radar Heads Radar Head
  Radar Displays
  Console 61 Console 61
  Console 64 Console 64
  Console 64 Console 64
  Console 64 Radar
  Exhibits Photographs of
Museum Exhibits

Royal Air Force Henlow Signals Museum

Console 64 re-furbishment.
(see above for description of this Console).

If you were trained at Locking on the Fixed Coil system, then the chances are that you worked on this very console!
The photo above was taken at RAF Locking in 1998.

Unlike the Consoles 60 and 61, the Console 64 does not contain any power supplies - they were supplied by power supplies situated in the Radar Office in the BPS (Bulk power supply) and the "Neg. Ref" rack. This meant that I had to build power supplies to give the appropriate DC supplies:

The circuit diagram for this can be see in the pdf file "BPS_NegRef_EmulatorSchematic.pdf". A photo of the prototype power supply can be seen here, this was later put into a (much safer!) cabinet. The original BPS power supplies used 3 phase mercury vapour rectifiers and CV345 valves to output the 250v stabilised supplies for the Deflection Amplifiers. Each BPS could supply up to 6 Console 64's. The new supply uses semiconductors throughout and uses high voltage Zener diodes and high voltage transistors for the stabilised supplies.

While I was building the power supply not only did Alf build the 50volt supply but also an equivalent of the Multimeter Type 100. This is actually better than the original type as it has a far larger meter. This meter is used for checking the various voltages and currents throughout the Console 64 using 24way Plessey sockets on each of the units. It was originally also used for most of the Radar Office equipment.

A pdf version of the AP 2897 Vol 1, book 2 (Consoles - wired frameworks) can be found here and may be useful if read along with the following. (Note, this is best downloaded and then displayed by Adobe Acrobat). A pdf version for the Radar Office Racks for Phase 1 can be found here, again, best viewed by downloading and viewing with Adobe Acrobat.

Throughout the following I was ably assisted by Jim Forrester who knew nothing about radar when we started (but he does now!). We started by checking that there were no electrolytic capacitors that required reforming in the console - there are no electrolytics in it (I never knew that before!). We then needed to connect up the DC power supplies and the mains supplies to the heater transformers on the input panel. To my surprise, I found that all the supplies (including the mains) go into the console on one 18 way Plessey plug (I didn't know that before either!).

I set RV6 on the video amplifier fully anti-clockwise to ensure that the CRT was cut off and then we switched on the power supply and switched on the console LT, set the HT on switch to on and waited for the thermal delay relay to operate. The LT light came on and the heaters on the valves came on too -marvellous! When the delay relay operated, the console immediately tripped because the +250v fuse had blown. After blowing another half a dozen fuses we found that the problem was due to 2 of the the co-ax cables into the blanking unit (they're just visible right at the bottom of the unit in this photo ) having been replaced and one of the braid wires was shorting out to the inner (this photo shows where the 4 cables from the deflection amps come into the unit at the top- the left hand 2 were the problem and are removed in this photo).

Having fixed this, we tried again, but the console tripped again. We set both the Stabiliser 51 and the Waveform Generator 80 to test and the console then stayed on. I set up the voltage regulators on the two units (yes, they both set up quite easily!) using Alf's Multimeter 100, and set the test/normal switches to normal and the console stayed on. I turned up RV6 on the video amp and we had a dot on the CRT ! I set up the EHT power supply (it was 400v low).

We then needed something to drive the display. Paul Edwards set about doing this using an Arduino processor. Paul has written an article about how he went about this. We needed if possible the X and Y scan (sine and cosine sawteeth), radar signals, radar bright-up, range rings, and video map. Paul eventually came up with all of these and they can be seen in this video (you will probably need to download this as it uses a lot of bandwidth). As I write this, Paul is doing his best to deal with the Phase 1A type interface to the height finder display. There is a further video shows 96 Russian Bears coming in from the east and 12 Phantoms on their way to intercept them.

Having obtained a dot on the screen, I tried to set things up, starting with the deflection amplifiers. The right hand Deflection Amp set up fine (130mA through each of the output valves), but the left hand one wouldn't set up on one of the valves (could only get 90mA). I struggled with this for several hours and eventually asked for help from the rest of the staff. The problem was with the output valve in the paraphase amplifier and we checked against the right hand amplifier and everthing looked very similar. Eventually after several hours, the current through the errant valve ceased altogether! Checking the voltage on the anode of the valve (top cap) revealed that there were no volts there (maybe we should have done this before), the cause being an open circuit co-ax between the deflection amp and the deflection coils. Mending this produced volts on the anode of the valve but no current through it! The problem this time turned out to be that the screen grid load resistor (in the Stabiliser 51 - I never knew this!) was open circuit. Replacing this allowed me to set up the output currents to 130mA on both output valves. So, the original problem had been the open circuit anode cable, the screen resistor had gone open circuit due to the large amount of current that had been flowing through it (90mA).

We set the centring controls on the control panel to mid point (5 turns from one end) and the dot on the screen was roughly in the center. Paul then came along with deflection waveforms from his Arduino set up and we applied these to the deflection amplifiers and obtained a rotating display (going wrong way round, but that was easily fixed - X and Y changed over). Due to the input voltage being 12v and the normal required sawtooth input being 50v, we had to have the display on the 80 mile range to get full deflection. This problem was fixed by changing the value of the input resistor to the op-amps in the deflection amps.

When Paul managed to produce range rings for us, we found that the octagonal blanking was apparently offset and we tried adjusting all sorts of things to fix this and eventually found that we could move the problem around the screen by moving the focus coil positionings. So, how to set up the focus coil? The instructions for this are in the above mentioned Console 64 A.P., Part 2, section 1, Chap 1, starting at para 38. I don't ever remember doing this, though I do remember seeing it in the AP. This setting up requires a Test Oscillator 101. We obtained the A.P. for this and were left with the option of either building one or modifiying our spare deflection amplifier slightly. We decided on the latter course and modified the deflection amp and drove it with an external audio sine wave oscillator (5c/s). While this didn't produce the required amplitude of output, it wasn't far off and enabled me to set up the focus coil positioning reasonably well. Going back to normal deflection showed that the setting up had had the desired effect and setting up the octagonal blanking worked! I suspect that the apparent blanking problem was actually caused by the electron beam hitting the side of the neck of the tube. Having got all this set up, we had a really sharp focus.

Not bad for a console that hadn't had power on it for around 40 years!

Other problems:

Next we hope to get a Phase 1A Height Finder system emulation on the PPI display - I have installed a Joystick to do this.

Unless otherwise stated, all photographs © Colin Hinson, all rights reserved.

Page last updated 12th June 2017 by Colin Hinson.