WA Radio Scanner Users' Group

Hi everyone.
I was wondering if anyone could help me out with my HF Antenna.
Im using a 1:1 balun for a half wave dipole with RG213.
I have done Continunity checks on the Cable (if thats how you spell it) WHILE the cable is isolated from the radio and antenna and that seems to be ok.
But when ever i connect the cable to the balun, there seems to be a short between the core and the sheilding.
basicly if i connect the cable to the balun and run a the test, it seems that the shilding and the core are connected and conducting, which basicly means the sheilding is radiating which explains why theres been alot of buzzing coming from my speakers in my room. Im not sure if this is how a balun works but it seems a little strange to me, dunno, does this possibly mean the balun is rooted?

slipknot wrote:Hi everyone.
I was wondering if anyone could help me out with my HF Antenna.
Im using a 1:1 balun for a half wave dipole with RG213.
I have done Continunity checks on the Cable (if thats how you spell it) WHILE the cable is isolated from the radio and antenna and that seems to be ok.
But when ever i connect the cable to the balun, there seems to be a short between the core and the sheilding.
basicly if i connect the cable to the balun and run a the test, it seems that the shilding and the core are connected and conducting, which basicly means the sheilding is radiating which explains why theres been alot of buzzing coming from my speakers in my room. Im not sure if this is how a balun works but it seems a little strange to me, dunno, does this possibly mean the balun is rooted?

Depending on the design of the 1:1 balun what you are seeing with your multimeter it is probably correct.

Check by putting a 50ohm load (dummy load or 50 ohm resistor network) across the balanced side of the balun and check it with an antenna analyser or your VSWR meter. If you put a 50 ohm load on the balanced side of your balun (ie the side where your dipole wires connect to) you should get a 1:1 SWR. A 100 ohm load will show a 2:1 SWR.

If using your transceiver & VSWR meter, make sure you don't exceed the power limit of your dummy load or resistor network. (ie: 20 x 1k 1 watt resistors in parallel will make you a 50 ohm, 20 watt dummy load or 44 x 2.2k 1 watts resistors in parallel will make you a 50 ohm, 44 watt dummy load.)

slipknot wrote: does this possibly mean the balun is rooted?

Probably not. Depends on how yours is constructed.

Have a look at the diagram here as one example of a 1:1 balun (http://www.webx.dk/oz2cpu/balun-schematic2.gif) and you will see that this balun would show a DC short but at RF it would perform as expected. Does not mean yours is not damaged but measuring with a simple meter will not prove much.

Buzzing in speakers, presumably amplified speakers, could be just RF overload. Wrapping the speaker leads around a ferrite rod or passing through a toroid ring may help.

well its mainly that im sure that theres RF leaking in my Shack becauce my SWR meter Backlight lights up when ever I transmitt , thats the thing. If i connect the lead to the swr meter for powering the back light without it attached to a power sourse and put the lead near the coax, it lights up, which im presumsing is leaking RF.

slipknot wrote:Hi everyone.

SNIP

, which basicly means the sheilding is radiating which explains why theres been alot of buzzing coming from my speakers in my room. Im not sure if this is how a balun works but it seems a little strange to me, dunno, does this possibly mean the balun is rooted?

Hi mate you need to make installing that RF earth stake a priority !
My shack PC speakers used to suffer from interference until I installed ferrite suppressors on the speaker leads just before they enter the audio amp.
Jaycar sell them http://www.jaycar.com.au/productView.as ... rm=KEYWORD
http://www.jaycar.com.au/productView.as ... rm=KEYWORD

VK6ZMS wrote: Hi mate you need to make installing that RF earth stake a priority !

HAhaha, thats what Neil said when i asked him yesterday, lol.
I think i might have to this time.
Thanks anyway guys.

So its just the casing that needs earthing Martin?