Larkspur vs Clansman antennae sections

[robin craig]

I am trying to help a gent who has Clansman and needs some antennae sections for a display.

How do I tell by measurement or connections what I have and will they fit his clamp mounts ?

Any direction gratefully received

 

 

 

[Chris Suslowicz]

Hi Robin,

They're basically the evolving "Aerial Rods 'F'" introduced before/during WW2, and will actually all fit Clansman bases.

The earliest (British) ones are 48" long, slightly tapered and with cylindrical ends:

ZA.0894 Aerial (Antenna) Rod 'F' No.1 - this is the bottom rod, fitting Aerial Base No.8, 10 & 11, etc

ZA0895 is No.2 (the centre rod) the bottom is necked down to enter the top of the No.1 and the No.2, allowing 3 and 4 sections to be used.

ZA0896 is No.3 (the top rod) this tapers to a closed end. (The WS38 "battle aerial" is a variation of this using spring steel rod welded into a plug and sometimes known as No.3B, I think.)

Up to four rods can be joined together, though the 16-foot (1+2+2+3) antenna is only really safe for static use.   

The next version was a Canadian improvement, with a rolled-in thread added to the top of the rods and the base of rods 2 & 3 to prevent them shaking apart and being lost from moving vehicles. These are 1.5" longer (49.5" or 1.2 metres overall).

Post-WW2 saw the tropicalised version:

ZA.44684 No.1 Mk.1/1

ZA.44683 No.2 Mk.1/1

ZA.44682 No.3 Mk.1/1

which were given NATO Stock Numbers (and a Domestic Management Code of Z42):

Z42/5820-99-949-1166 Antenna Rods, F. Mk.2 - Bottom (equal to ZA.44684)

Z42/5820-99-949-0985 Antenna Rods, F. Mk.2 - Middle (equal to ZA.44683)

Z42/5820-99-949-0986 Antenna Rods, F. Mk.2 - Top (equal to ZA.44682)

Enter Clansman, and the rods were shortened to a standard 1 metre length.

The 1986 Racal Antenna Catalogue still lists the earlier version, of course, and they will interchange with the metric ones.

Section.                 Steel                             Racal #.     Fibreglass/GRP.        Racal #

No.1 (Bottom).      5985-99-630-8455    (MA681).    5985-99-649-8138.   (RA746)

No.2 (Middle).      5985-99-630-8456    (MA682).    5985-99-649-8139.   (RA747)

No.3 (Top).            5985-99-630-8457    (MA683).    5985-99-649-8140.   (RA748)

(Hopefully this doesn't get reformatted once I hit "Send"!

Best regards,

Chris.

[robin craig]

Thank you very useful information

[AlienFTM]

As implied in previous answers, Larkspur used 4' sections. As a RAC reconnaissance regiment, we had HF command nets to get distance. The C13 HF radio might get three rods (12') when using a low frequency (frequency is inversely proportional to wavelength). The ATU (Antenna Tuning Unit) for C13 would electronically optimise the antenna to a quarter of the wavelength. At long wavelength (low frequency) 12' of rod tuned better to the transmitted signal than 8'. Mounted on the turret back of a Scorpion, 12' of rod was very high. We had adaptors that allowed us to slope the rods and reduce the overall height. Static, a good RAC Control Signaller could use the slope to increase range. Mobile, the rod would swing back into the wind. More often than not, 12' was too much rod.

If the physical rod was longer than ¼ wavelength, the ATU would try to tune to ½ wavelength and a poor signal would result. C13 could tune between 1.5 and 30MHz. We usually worked in the range about 2½-5MHz

VHF C42 and B47 sets worked in the range 36-60MHz and always used 8' of rod, because that's what their ATU expected.

We (15th/19th The King's Royal Hussars, 3 Armd Div Recce Regt from 1 Jan 78) converted from Larkspur to Clansman in 1979 (I did the last Larkspur Control Signaller course in 1978). HF C13 was replaced by VRC321, and VHF C42 by VRC353, but the Recce HF command nets had moved to VHF about the end of 77, so our Scorpions got two times VRC353 after the Clansman conversion. Sometime after I changed career, they realised that a Recce vehicle didn't need two monster sets, and one 353 was replaced by a manpack PRC351/2, which had the advantage, obviously, of being used dismounted. All the work took place on the Squadron (Combat Team) command net. Troop chatter nets were frowned upon. If a team went out on foot, with Clansman it was easy to rebroadcast the Recce team on 351 onto the Combat Team command net.

Clansman used 1m rods, a 2m length for VHF, 3m for HF

Caveats. The Control Signaller course lasted 6 weeks (basic radio including Voice Procedure lasted 4). I cannot quote it all here. Most isn't relative to your query anyway.

Set designations change. UK/VRC aligned with American designations. After the introduction of Clansman, the old Larkspur designations changed from eg SR (Station Radio) C42 to SRC42, to align with the new Clansman designations.

I've tried to keep it brief, but sorry.

I've described a seven year period between 1975 and 1982. Things outside of this period may vary. But Wave Theory doesn't.

It's nearly 50 years ago and I've been out of running the Battlegroup command net and division command net for over 40.

Hope this helps. If not, I hope it's been interesting.