Workday 21st August 2021


Our main focus for the day was the replacement of the three ‘on-launch’ waveguide horns at the corners of the T86 cabin. When our T86 was recovered these were missing, literally snapped off the cabin walls shearing the securing bolts and waveguide sections feeding the horns. This was probably down to the attention of metal thieves many years ago before the radar came into our care. Fortunately we were able to recover three replacement waveguide horns from a derelict T86 on the North Luffenham airfield and these are now being fitted. Dave and Pete’s task was to restore the mounting bolt holes for the horns and deal with the sheared studs and twisted waveguide ends.

Mounting and waveguide connection.
Initial fit of one of the horns

This restoration task is work-in-progress. To enable the restoration of mounting holes a repair kit has been created as shown here.

The T86 aerial assembly was tilted back to enable further access for painting. Note. Several assemblies from the aerial system have been removed and restored ready to be refitted.


It can be confirmed that the display fault is due to a U/S monitor. A spare will be taken to Cosford this coming Saturday and if time allows some fault finding will be carried out.

Pete H

Activity Update to WE 20th August 2021

This is a compendium update of activities up to August 20th


The Tx and Rx reflectors have had a coat of black paint (for now), see accompanying photo.

We are nearing the conclusion of the refurbishing and painting of the aerial assembly and pedestal platform but it does seem like a never-ending task due to all the waveguide runs and inaccessible places. Still to do are reassembly of all the items removed, JA aerial, In-Flight aerial etc. which is a two-man job.

Some parts of the aerial system also require the aerials to be tilted back to finish the painting; this to is a two man job; one on the brake switch and one on the hand crank to wind the aerials in elevation. Moving the aerials in bearing is not a problem, as long as the brake is off!

Aerial positioning and control (bearing) Part 1

In the odd moments I get I’m still trying to unravel the mysteries of the bearing brake system and the associated sector, end stop and limit switch operation. A total of 14 microswitches (I think). I know what switches should operate and when but that’s the start of the problems in that the synchro dials that indicate the mils of the aerial position do not tie up with the physical position. SJ operates at the vehicle centre line (straight out over the rear of the cabin) and the corresponding mils should indicate ‘0’ but they don’t, they indicate 24xx or something around there. Is it a set up problem? Of course when operating the T86 operationally you never actually checked the mils reading for aerial positions, or I can’t remember doing it. This photo shows where the various microswitches are located, they reside on the rotating pedestal shaft, the Bearing Stop Unit and the Switch Unit Bearing (the Geneva Mechanism and it microswitches sit below this unit).

Also see the Pedestal Assemblies drawing here.

Aerial positioning and control (bearing) Part 2

To add to the headache….. With the aerials at ‘0’ and SJ is operated (closed) by a small spigot on the main pedestal shaft the Sector the Limit and Sector lamps are out on the Pedestal End Stop Indicator out, sounds correct. So why is the SA /SB Lamp on, this lamp should only be on in an end stop? Why is the Limit Override lamp always on? Operating the Limit override switch on the console makes no difference but the Limit Override lamp goes out if the Bearing Brake is applied on the Console. I haven’t found a description of when the lamps come on and in which sequence (yet). Only answer is to finish my redrawing of the circuits controlling the lamps on the Pedestal End Stop Indicator.

I read up on a couple of APs; the story you get depends on which AP you read.

AP 1: Move the aerials to the Datum Zero Line on the trailer and if required release the clutch under the coarse mils dial and adjust to zero.

AP 2: Move the aerials to the Centre Line. Check the micro switch(s) operation at the mils they operate at and allow for any difference from the mils reading at the Centre Live from zero (implying the mils are not zero at the centre line).

Here is the engraved notch on the pedestal shaft that indicates the Centre Line.

The first thing I don’t understand is: When moving the aerials to around 200 degrees (CW or CCW) the Limit lamps light and with a bit more movement the Sector lamps light. That doesn’t look right to me hence the checking of the mils dials to see if I was actually at the centre line when starting or if I was 360 degrees out. The mils reading is not desperate if not zeroed but I currently can’t relate it to the mils at which the microswitches operate. The Sector lamps are illuminated by SC/SD in the Switch Unit Bearing while the Limit lamps are illuminated by SM/SN on the pedestal shaft.

All I want to achieve are some straight forward notes for us and anyone in the future who will be moving the aerials and what the indications mean but mainly to prevent someone ripping out the cable winder.

The clockwise and counter clockwise sectors of the aerial movement in bearing checked. Outer sector indicators on the console checked, see below.

A suspected fault with two indicators on the pedestal indicator unit remains to be investigated.

Protective wooden covers were constructed for the pedestal roof as painting of the roof commences. New duck boards have been constructed for the roof but these will only be fitted once restoration is complete, see accompanying photo.


Simulator run up for a check and all booted correctly. The simulator was left to run while other work was carried out.

Returning to check the simulator I found a fault had occurred on one of the display monitors (Technical Supervisor position).

The monitor is not suspect but a CHARGE (video display processor) Pixel Store is the more likely fault and I will swap the CHARGE Pixel Store with a spare, or extend the fault finding, spares are available.

Pete H

Work Day 31st July 2021


Many small tasks progressed with, painting the waveguide desiccator clamps black, sections of not easy to access waveguide, also a start made painting the waveguide supports on the aerials.

Stripping old paint off the stainless steel positioning spigots on the aerial beam was carried out.

A problem with repainting the aerial assembly is that it shows up items we would not have considered for refurbishing. An example; the Perspex covers for the aerial elevation position indicators, see below.

The metal covers and the Perspex viewing windows have been removed for refurbishing away from Cosford and the corrosion shown in the photo will be treated before reassembly. Usual problem with refurbishing such items, dirt and old paint.

No apologies for another photograph of the aerials.


The remaining ‘R’ clips have at long last been fitted to the roof support struts! A spare Harrison X150 amplifier in the LCP has been removed for testing. We have a total of three X150 Boost Blast amplifiers, originally thought to only have two!

The simulator was not run yesterday.

Away from Cosford


A few long outstanding tasks remain to be tackled and a start has been made. The LCP roof join canvas securing clamps are being refurbished and painted. This photo shows three of these clamps, stripped of paint.

They are copper bars with brass on one side and besides old paint they are heavily tarnished. The clamps must have been nice and shiny when new! There are 33 of these clamps (I suspect there are a few spares). Also being refurbished are the alloy plates that secure the leather retaining straps for the canvas roof cover. Needless to say the original overall canvas roof was not with the LCP and the canvas roof join covers have completely rotted.


For the future display and moving of the T86, plus current refurbishing work, it is important to understand aerial movement, braking, aerial removal and pedestal retraction. The aim is to interpret the information contained in T86 APs and create a set of notes on these topics relevant to the operations just described. Currently, -24V supply has been restored (not using the original D Rack and F Rack power supplies) so that indicators, pedestal microswitches and aerial brakes operate. This photo shows the Pedestal Indicator Unit, the lamps indicate aerial positioning and overrides.

A priority task is to document when these lamps come on in relation to the bearing position indicator, dials graduated in mils. One example, the Limit Override lamp stays on irrespective of operating the Limit Override switch on the console (D Rack). Why? The T86 APs have wiring diagrams and testing procedures but we do not have information on the processes and procedures we need – unless we don’t have the right APs!

Pete H

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