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MILITARY RADIO RACAL PORTABLE LOOP ANTENNA MA 4953A


Tracey_Gardner
 

 
I came across this 2.8 - 16MHz Racal loop antenna on eBay.
I've never seen one of these before.

eBay item number:193763750811


Regards

Tracey G5VU


Chris_Suslowicz
 

Tracey (G5VU) wrote:


I came across this 2.8 - 16MHz Racal loop antenna on eBay.
I've never seen one of these before.
I think Mike Buckley (or one of the Vintage Operating Group?) has got one, because I've seen it erected at Beltring on occasion.

Not sure if it's receive only...


eBay item number:193763750811
Searching Google gets me a bunch of deleted Italian spam pages (presumably using the Racal item as bait), and a long expired picclick auction that apparently ended at £90, so no clues as to whether it's receive-only (and it's more recent than 1980, so not in the catalogue we have archived).

Chris. (G8KGS)


Henk_Parasetguy
 

Hi
In the drawing on the last photo it says: (cable) "to transceiver".


Kind regards,
Henk - Parasetguy
http://www.paraset.nl/index.htm
http://www.paraset.nl/hut12_warehouse/index.htm



-----Oorspronkelijk bericht-----
Van: wireless-set-no19@groups.io <wireless-set-no19@groups.io> Namens
Chris_Suslowicz
Verzonden: dinsdag 24 november 2020 14:58
Aan: wireless-set-no19@groups.io
Onderwerp: Re: [wireless-set-no19] MILITARY RADIO RACAL PORTABLE LOOP
ANTENNA MA 4953A

Tracey (G5VU) wrote:


I came across this 2.8 - 16MHz Racal loop antenna on eBay.
I've never seen one of these before.
I think Mike Buckley (or one of the Vintage Operating Group?) has got one,
because I've seen it erected at Beltring on occasion.

Not sure if it's receive only...


eBay item number:193763750811
Searching Google gets me a bunch of deleted Italian spam pages (presumably
using the Racal item as bait), and a long expired picclick auction that
apparently ended at £90, so no clues as to whether it's receive-only (and
it's more recent than 1980, so not in the catalogue we have archived).

Chris. (G8KGS)


Michael O'Beirne
 

Tracey

 

That Racal loop was in the Racal Antennas’ catalogue some years ago.  I think Mike here has one.

 

I have never used one so I can’t comment.  I gather they are easy to set up and tune.  You just turn the control in the green box at the base for max meter reading.  I think it contains a vacuum capacitor tuning the loop.

 

I made a “Chinese” copy of this loop for a military exercise at the old Chelsea Barracks to stations across London using SSB with PRC320s.   I used heavy duty coax spread over a dismountable crucifix frame (connecting only the outer braid) with a similar sized coupling loop at the apex as per the Racal loop, and tuned the loop with a two large transmitting capacitors in series and used the tuning meter on the PRC320 for maximum signal.  It gave a very sharp tuning peak (as you would expect).  It was almost as accurate to tune for maximum signal.

 

The received RF noise level on the roof of the barracks with the issued whip was terrible.  That’s par for a city.

 

The signal level was lower with the loop but the signal to noise ratio was considerably better thanks to the very sharp tuning.  I’m quite a fan of tuned loops.

 

73s

Michael

G8MOB

 

 

 

From: wireless-set-no19@groups.io <wireless-set-no19@groups.io> On Behalf Of Tracey_Gardner via groups.io
Sent: 24 November 2020 13:10
To: Wireless-Set-No19 group <wireless-set-no19@groups.io>
Subject: [wireless-set-no19] MILITARY RADIO RACAL PORTABLE LOOP ANTENNA MA 4953A

 

 

I came across this 2.8 - 16MHz Racal loop antenna on eBay.
I've never seen one of these before.

eBay item number:193763750811


Regards

Tracey G5VU


Michael O'Beirne
 

Chris

Further to my text of a few mins back I have looked in two volumes of Jane
and there is no reference to a MA 4953A but there is tactical loop, the RA
961, which is what I had in mind.

From memory the max power is 100W.

I confirm that I too saw one with Mike B's Land Rover some while back.

73s
Michael
G8MOB

-----Original Message-----
From: wireless-set-no19@groups.io <wireless-set-no19@groups.io> On Behalf Of
Chris_Suslowicz
Sent: 24 November 2020 13:58
To: wireless-set-no19@groups.io
Subject: Re: [wireless-set-no19] MILITARY RADIO RACAL PORTABLE LOOP ANTENNA
MA 4953A

Tracey (G5VU) wrote:


I came across this 2.8 - 16MHz Racal loop antenna on eBay.
I've never seen one of these before.
I think Mike Buckley (or one of the Vintage Operating Group?) has got one,
because I've seen it erected at Beltring on occasion.

Not sure if it's receive only...


eBay item number:193763750811
Searching Google gets me a bunch of deleted Italian spam pages (presumably
using the Racal item as bait), and a long expired picclick auction that
apparently ended at £90, so no clues as to whether it's receive-only (and
it's more recent than 1980, so not in the catalogue we have archived).

Chris. (G8KGS)


AlanM
 

It is very similar to the Racal RA961 Tactical Loop Antenna.

The spec for the 961 quotes a frequency range of 3-15MHz and 100W PEP and claims sky wave comms over path lengths of up to 1500 Km

Alan M

 


Michael O'Beirne
 

Chris

The one design element with that tactical loop that concerns me is the
number of moving joint surfaces at the three corners and the two connections
to the ATU. We all know that any avoidable resistance in a very hi-Q
transmitting loop is big bad news. That is why with my loop the braid of
the coax was soldered direct to the big variable tuning capacitors and why
they were connected in a split-stator arrangement to eliminate any losses in
the wipers. Braid itself is a mass of cross connections and not ideal but
it was the best I could do.

Perhaps Mike B will tell us of his experiences with his loop. At low
frequencies there is a lot of high angle radiation and should be ideal for
NVIS working.

73s
Michael
G8MOB


Pete_G4GJL
 

Chris, the instruction sheet at the end of the photo collection refers to tuning a transceiver, albeit I would assume a relatively low power one!

Pete
G4GJL

On Tue, Nov 24, 2020 at 1:57 PM Chris_Suslowicz <chris@...> wrote:
Tracey (G5VU) wrote:

>
>I came across this 2.8 - 16MHz Racal loop antenna on eBay.
>I've never seen one of these before.

I think Mike Buckley (or one of the Vintage Operating Group?) has got one, because I've seen it erected at Beltring on occasion.

Not sure if it's receive only...

>
>eBay item number:193763750811

Searching Google gets me a bunch of deleted Italian spam pages (presumably using the Racal item as bait), and a long expired picclick auction that apparently ended at £90, so no clues as to whether it's receive-only (and it's more recent than 1980, so not in the catalogue we have archived).

Chris. (G8KGS)






Andy_G8JAC
 

The user handbook is here:

http://pmrconversion.info/ra961USER.htm

 

Andy  G8JAC