Aerial problem...

[Jake the arsonist]

Hello Forum.
As said in my intro post, have got my old CB out of storage. Radio and home base aerial all checked and functional. For mobile use I have ( or had ) an Oscar One 11se aerial - a base loaded whip, upon checking the Oscar with a multimeter, I found that there is zero resistance between the two parts of the connector. Rather than just chucking it, anyone know if I can repair it........just asking.
I hadn't intended to use it whilst driving, but it was easier to set up than dragging the home base aerial up into the hills.
I presume the base contains a coil that has probably corroded after so long.
I would welcome your comments.
Thanks, Dave.

[Jake the arsonist]

Cont'd.....
I opened it up, and took a couple of pic's but I'm damned if I can work out how to get them on here. ( I'm about as good as a potato when it comes to i.t. )

There's a thick, lacquered copper wire coil, starting at the base ( screen side ) 2.5 turns up to a tap point that goes into the ceramic former, there are a further 7.25 turns to the top screw onto which the steel whip is screwed. There's no sign of corrosion.

On the face of it, I can't see how it would have worked, as the coil links directly between signal and earth, as it were.

Would someone be able to educate me a little on this....

Thanks, regards, Dave.

[The Collector]

I'm not up on the techy-side of mobile aerials. All I know is usually the inner and outer of the SO-type connector are separate and don't show a "short" as a rule.
Some homebase aerials nowadays are different, so it could be something similar with the Oscar (I've never owned one).

Providing you've got 2 radios that is, all I can suggest is you set up the homebase side of things and then try the Oscar from say half a mile away in the car to see if it receives the homebase signal nice and strong (end of the scale) if it's much less than say s9, then something's wrong somewhere so don't try and TX on it.

[Jake the arsonist]

Thanks for the reply...

If the aerial is a dead short, will it damage the RF side of the radio at all?

Otherwise I will try your suggestion.

Again, many thanks, regards Dave.

[The Collector]

So long as you don't transmit, it shouldn't do any damage at all. If you can hear stuff on your homebase nearby but then can't hear it in your car outside (albeit maybe a slightly lower signal if your homebase aerial is up high), then something's wrong.

I'm not sure if there's anything to be found on the net about the Oscar by using Google etc. or by using this site's own search feature, but it might be worth a mooch?

[Jake the arsonist]

Thanks Collector,
I will have a pole about and see what goes....

Cheers, Dave

[Jake the arsonist]

#poke......!

[cubwolf]

It will show a short its just the way its designed.
I think the sirios might be the same.

[Tigersaw]

Some antenna are designed as shunt loaded. They will look a short to a DC meter but not to RF.
As above, if it receives as well as expected or compared, then try it on TX, low power first.

https://electronics.stackexchange.com/q ... match-work

[DX-Digger]

The tap or feed point on the coil is the 50 Ohm feed point. yes it will measure short circuit however the radio see's a 50 Ohm impedence When resonant on 27MHz etc .
Some silver rods are the same.

[Jake the arsonist]

Thanks for the replies....
Dx-digger the diagram looks exactly like the guts of the Oscar.....it makes sense.
I will get my arse in gear and try it. Only have one radio, so a mate is coming over tomorrow, so will fire it up.
Thanks again, regards, Dave

[Jake the arsonist]

Thanks to the guy's above, I think it's alive!

Switched on this afternoon to see what's going on.... noise floor was S2 - S3, that's about normal....at about 3.30 p.m. it shot up to S7, constant roar.
After a quick panic, change of p.s.u., coax and underwear, I flicked across the full range ( of my radio ) from 26.965 to 27.99125.
It covered the whole lot. Lasted about half an hour, then dropped back to S2-3.
Half hour or so later it happened again.
I live not far from Tolworth roundabout on A3....has anyone else heard this?

[The Collector]

I used to get blasts of "static" rising from nothing to 30+ about every 15 minutes or so back in the early 80's. Years later, we discoved it was the heating thermostat after it went faulty, got changed and years of interference disappeared. It could be something similar. You could try running your radio off a car battery to rule out direct mains interference, then if it starts, turn off power at the fuseboard and it'll rule out anything else electrical in your house. If it's still there, then you've got a battle on your hands.