I have some questions about the choke and feed line on the Cobwebb.



Does the co-axial choke balun work better if the cable is wound on top of
each other into a tube shape rather than just winding it round and zip tying
it together in a round bundle?



Can I attach a SO239 Chassis socket to the end of the box where the coax
enters and then plug a PL259 into that for the feeder or will the socket
allow current to bypass the choke balun and enter the feed line?



Thanks

The reason for wanting to know the above is, I want to use RG58 inside the
box and then run RG213 up to the box for the feeder from the radio. I don't
want to do this if the S0239 socket is going to allow the feed line to
radiate. Can any one please advise?

Many thanks


"Barrett" wrote in message
k...
I have some questions about the choke and feed line on the Cobwebb.



Does the co-axial choke balun work better if the cable is wound on top of
each other into a tube shape rather than just winding it round and zip
tying it together in a round bundle?



Can I attach a SO239 Chassis socket to the end of the box where the coax
enters and then plug a PL259 into that for the feeder or will the socket
allow current to bypass the choke balun and enter the feed line?



Thanks

Richard Clark wrote:
On Thu, 20 Mar 2008 22:43:25 GMT, "Barrett"
wrote:

I don't
want to do this if the S0239 socket is going to allow the feed line

Feedline radiation is a consequence of common mode currents. Common
mode currents are a consequence of unbalance. Coax systems are
unbalanced. To correct this, you need to choke the coax line at the
feed point, and probably again a quarterwave away from the feedpoint.

Coax feedlines are no more or less balanced than twinlead lines. Common
mode current can occur on either, and for the same reasons, and either
can be balanced by suppressing or avoiding creation of common mode
current. The topic is discussed in more detail at
http://eznec.com/Amateur/Articles/Baluns.pdf.

Roy Lewallen, W7EL

On Thu, 20 Mar 2008 22:43:25 GMT, "Barrett"
wrote:

I don't
want to do this if the S0239 socket is going to allow the feed line

Feedline radiation is a consequence of common mode currents. Common
mode currents are a consequence of unbalance. Coax systems are
unbalanced. To correct this, you need to choke the coax line at the
feed point, and probably again a quarterwave away from the feedpoint.

73's
Richard Clark, KB7QHC

I think I have a problem on the 28MHz band with the homebrew Cobwebb that I
have made.

The SWR is 1.1 and is tuned at 28.500MHz.

If I listen to this band it receives strongest at 28.500 and drops off
sharply after about 300KHz each side along with a rise in SWR It can reduce
a S9 signal down to S1 on both sides.

Is this how the Cobwebb performs or is there some thing wrong with it?



I like to listen to a few people on 27MHz that I know. They are only 5 miles
away. I have no problem hearing them on a G5RV but I can only just here them
on the Cobwebb.



Many thanks



"Barrett" wrote in message
k...

I have some questions about the choke and feed line on the Cobwebb.



Does the co-axial choke balun work better if the cable is wound on top of
each other into a tube shape rather than just winding it round and zip
tying it together in a round bundle?



Can I attach a SO239 Chassis socket to the end of the box where the coax
enters and then plug a PL259 into that for the feeder or will the socket
allow current to bypass the choke balun and enter the feed line?



Thanks