Unknown CB radio accessory - UK Vintage Radio Repair and Restoration Discussion Forum

newlite4 · 20th Dec 2022, 4:03 pm

I picked up this device amongst a bundle of CB radios on Sunday. I am unsure as to what this is. It looks like a portable dipole antenna or balun assembly. A coax lead enters the tubular section and two single wires exit from each end. Any ideas?
Neil

G6Tanuki · 20th Dec 2022, 4:21 pm

It's a small vertical dipole antenna; try measuring the length of the wires.

Such things were popular as portable antennas not necessarily for CB but for air-band and 2-metere-band use, and for use with scanners.

The wire on the end-with-the-arrow-on-the-centre-piece wiill probably have a loop or something so you can hang it up vertically.

Jon_G4MDC · 20th Dec 2022, 4:36 pm

Looks to me like the two arms are different lengths or...?

newlite4 · 20th Dec 2022, 5:43 pm

Thanks for the information and such a quick response. The short wire with the loop coming from the arrow end is 130cm and the long wire coming from the opposite end is 298cm.
Neil

Jon_G4MDC · 20th Dec 2022, 6:14 pm

~3m is more or less plausible as a 1/4 wave for the 11m band.

1.3m seems too short to be useful unless it has been loaded in some way. Any sign of a coil inside the tube? Then it's looking like a wire version of the wot-pole. It was intended the short element was uppermost (radiator) with the long one below (counterpoise).
This complied with the licence stipulation that max radiator length was 1.5m (probably now gone?)

Many reckoned they worked better upside down and plenty were seen installed like that.

SiriusHardware · 22nd Dec 2022, 12:51 pm

The yellow arrow on one end of the tube would appear to be a 'this way up' indicator, suggesting that the coil of wire to the left in the image is meant to be the active / upright element. If there is indeed a loading coil in the tube then the wire sticking out of that end is likely to be the shorter of the two.

20th Dec 2022, 4:03 pm	#1
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,806	Unknown CB radio accessory I picked up this device amongst a bundle of CB radios on Sunday. I am unsure as to what this is. It looks like a portable dipole antenna or balun assembly. A coax lead enters the tubular section and two single wires exit from each end. Any ideas? Neil Attached Thumbnails __________________ preserving the recent past, for the distant future.

20th Dec 2022, 4:21 pm	#2
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,007	Re: Unknown CB radio accessory It's a small vertical dipole antenna; try measuring the length of the wires. Such things were popular as portable antennas not necessarily for CB but for air-band and 2-metere-band use, and for use with scanners. The wire on the end-with-the-arrow-on-the-centre-piece wiill probably have a loop or something so you can hang it up vertically. __________________ I'm the Operator of my Pocket Calculator. -Kraftwerk.

20th Dec 2022, 4:36 pm	#3
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Unknown CB radio accessory Looks to me like the two arms are different lengths or...?

20th Dec 2022, 5:43 pm	#4
newlite4 Octode Join Date: Nov 2003 Location: Bath, Somerset, UK. Posts: 1,806	Re: Unknown CB radio accessory Thanks for the information and such a quick response. The short wire with the loop coming from the arrow end is 130cm and the long wire coming from the opposite end is 298cm. Neil __________________ preserving the recent past, for the distant future.

20th Dec 2022, 6:14 pm	#5
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Unknown CB radio accessory ~3m is more or less plausible as a 1/4 wave for the 11m band. 1.3m seems too short to be useful unless it has been loaded in some way. Any sign of a coil inside the tube? Then it's looking like a wire version of the wot-pole. It was intended the short element was uppermost (radiator) with the long one below (counterpoise). This complied with the licence stipulation that max radiator length was 1.5m (probably now gone?) Many reckoned they worked better upside down and plenty were seen installed like that. Last edited by Jon_G4MDC; 20th Dec 2022 at 6:22 pm.

22nd Dec 2022, 12:51 pm	#6
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,586	Re: Unknown CB radio accessory The yellow arrow on one end of the tube would appear to be a 'this way up' indicator, suggesting that the coil of wire to the left in the image is meant to be the active / upright element. If there is indeed a loading coil in the tube then the wire sticking out of that end is likely to be the shorter of the two.