THE KH SERIES W/T CONTROL UNITS

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THE KH W/T CONTROL UNITS

Written by Godfrey Dykes

© RN Communications Branch Museum/Library

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To incorporate many of the lessons learnt during WW2 and to accommodate new equipment which had been designed from 1943 onwards, the Type 601 Series of transmitters for example, the Admiralty introduced a new and comprehensive modern system of control which allowed any transmitter and/or receiver to be used at their local positions or at any remote position.

There were many varieties to cater for all needs in every class of ship or operating condition, and these were the main fits:

	FIT	WHERE FITTED

	KHA	Battleships and Cruisers, which included KFF the control system for fighter aircraft (see KC/KF Series)
	KHB	Aircraft Carriers which included KFG the control system for fighter aircraft.
	KHD	Destroyers.
	KHE	Light craft other than Destroyers.
	KHF	Light craft with separate transmitter and receiver offices, e.g. fast A/S Frigates.
	KHG	Air Direction Frigates.
	KHH	Submarines, coastal and inshore minesweepers, and other small craft with three or four transmitters.
	KHJ	Seaward defence boats and other small craft with only two transmitters.
	KHK	Submarines SSA1 and 2 outfit.
	KH(Y)	Fitted with type 691 equipment in ships with no KHA to KHF.

All these systems functioned by using the CCX (Control Circuit Exchange) which routed voltages, control lines, Morse Key/Microphone PTT (press to talk) button, ready, busy, unavailable signals from remote users to and from equipment wired to the CCX's all married temporarily together by plug and socket actions. Multi-users, individual user, listening only, transmitting only, were the normal combinations. Here then are a few pictures of the terminal control outfits which were fitted at the remote user positions starting with the CCX. The majority come from the Destroyer KH Fit, namely the KHC TO KHD, but there are a couple of KHA-KHB outfits shown.

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The biggest fit ever achieved then, and almost certainly carried over to today's fits (simply basing a modern warship of today with one immediately post WW2) was the fit KHB with an associated FAA fit of KFG. It is fitting therefore that we post a file of that fit.

and then have a look at this file HMS EAGLE KHB WITH KFG and just to prove how efficient and well liked the F.A.A., KFG system was, long after the death of the KH system, supplanted by the KMM/KMP systems (full ICS and ICS Mixed fit), the KFG system, now improved to KFJ but nonetheless very much KH style, remained at sea in a modern environment. Look at this picture which was a part of the full ICS fit in the carrier Hermes.

> The KH Series served the Fleet well until the arrival of the FULL Ratt/SSB equipments (we were using RATT through the KH long before this event took place with the 601 Series and the famous 89Q). COMIST (Communications in the Short Term) brought new equipment into the Fleet although not necessarily a new Control System. With the introduction of ICS in the 1960's (Integrated Communication Systems) (the first being ICS1) came the KM Series, and KMM was assigned to ICS1. The Marconi NT204 Transmitter, the Type 640, was widely fitted in COMIST ships, and it stayed on as the main transmitter for a fit known as ICS Mixed, where the reception side equalled the reception side of ICS1 proper. The Mixed Fit was assigned KMP. The major difference between KMM and KMP was that the former had a central Control and Monitor Desk (CMD) from where all HF/MF tuning took place, whereas in KMP ships, HF/MF transmitters were tuned in-situ. In the ICS scuttle on the Transmitter Matrix, we cover KMM (for ICS1 and ICS2) and KMP (for ICS1 and 2 Mixed Fits).

Before we move off and away from Control Outfits, there were a few other system which began with the letter 'K'. Shore stations had control outfits, one of them being KSK. In the 1960's/70's, we used on-line voice on HF, VHF and UHF. The main crypto equipments involved were called the BID150 with a second equipment known as the KY8; also, the Speech Privacy for HF (a system known as LINCOMPEX) was either simple SPEECH INVERSION or a system of MULTIPLE SPEECH INVERSION from level 1 to level 5 (5 times inverted or scrambled!). The radio equipment deployed was the 692 transmitter and the CUJ receiver for UHF, and Army transceiver equipment (hard wired or jury rigged) known in the Navy as the Types 631 and Type 636, both VHF, but on slightly different frequencies. Whilst the on-line operation could have been conducted through a KM Series CCX, it was necessary to route all off-line AF through a special Control System so that eavesdropping was not possible. To do this, the KKA and the KKB ('A' for UHF and 'B' for VHF) were introduced, which like the KMM/KMP, was a simple plug and socket system to marry the remote user to the equipment (crypto and radio). For HF however, the LINCOMPLEX equipment was offered to any suitable HF transmitter/receiver circuit via the normal KMM where one of the plugs on the CCX Lower was marked "LINCOMPEX" although the letter KKC were coined for this system. This first thumbnail shows the system as a block diagram and the second thumbnail briefly describes how LINCOMPLEX worked.

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