Can the 20m, 75ohm matching stub perform double duty as a common mode
choke?

ie: will it hurt if i wind the stub around something like 4" PVC?

--Teh

wrote in news:1178935164.295223.69320
@o5g2000hsb.googlegroups.com:

Can the 20m, 75ohm matching stub perform double duty as a common mode
choke?

ie: will it hurt if i wind the stub around something like 4" PVC?

Best thing to do is try it and let us know your results. I would
guess that it might have some small effect on the match. In my own case,
there really isn't a good place to put the coil near the antenna, so a
choke is better right before entering the house.

- Mike -

In my case I inserted a bead type common mode choke at the end of the
matching stub and at the beginning of the 52 ohm coax run to the house. The
grass soon grew up over the coax and the choke, and never once did my lawn
mower chop into the coax or the choke.

-- John, N9JG

"Mike Coslo" wrote in message
36...
wrote in news:1178935164.295223.69320
@o5g2000hsb.googlegroups.com:

Can the 20m, 75ohm matching stub perform double duty as a common mode
choke?

ie: will it hurt if i wind the stub around something like 4" PVC?

Best thing to do is try it and let us know your results. I would
guess that it might have some small effect on the match. In my own case,
there really isn't a good place to put the coil near the antenna, so a
choke is better right before entering the house.

- Mike -

John, N9JG wrote:
In my case I inserted a bead type common mode choke at the end of the
matching stub and at the beginning of the 52 ohm coax run to the house. The
grass soon grew up over the coax and the choke, and never once did my lawn
mower chop into the coax or the choke.

-- John, N9JG

First time I ever heard of "Murphys' Law" failing! :-)

Regards,
JS

I should mention that my lawnmower is setup for a fairly high cut.
-- John

"John Smith I" wrote in message
...
John, N9JG wrote:
In my case I inserted a bead type common mode choke at the end of the
matching stub and at the beginning of the 52 ohm coax run to the house.
The grass soon grew up over the coax and the choke, and never once did my
lawn mower chop into the coax or the choke.

-- John, N9JG

First time I ever heard of "Murphys' Law" failing! :-)

Regards,
JS

On Sat, 12 May 2007 19:25:22 -0500, Mike Coslo wrote:

wrote in news:1178935164.295223.69320
@o5g2000hsb.googlegroups.com:

Can the 20m, 75ohm matching stub perform double duty as a common mode
choke?

ie: will it hurt if i wind the stub around something like 4" PVC?

Best thing to do is try it and let us know your results. I would
guess that it might have some small effect on the match. In my own case,
there really isn't a good place to put the coil near the antenna, so a
choke is better right before entering the house.

- Mike -

I eneded up making a new 20m stub out of RG-6 and wrapped 11 turns onto
some 4" PVC. I then mounted this to the feed point of the antenna.

http://teh.3leggedcat.com/ham/matching-stub.jpg

I made a similar coil at work, where I have access to better test
equipment, and if I did the measurements correctly, the choke peaks right
at the 20m band.

As for the rest of bands, the measurements appear to be normal for this
antenna. Approx 80kHz of 80m, 250kHz of 40m, and full band on 30/20/15
and 10 with SWR 1.5.

An added bonus might be that the SWR on 12m is 1.3, so it looks like I
have a HF7V now.

--Teh

Tehrasha Darkon wrote in
:

I eneded up making a new 20m stub out of RG-6 and wrapped 11 turns
onto some 4" PVC. I then mounted this to the feed point of the
antenna.

http://teh.3leggedcat.com/ham/matching-stub.jpg

I made a similar coil at work, where I have access to better test
equipment, and if I did the measurements correctly, the choke peaks
right at the 20m band.

As for the rest of bands, the measurements appear to be normal for
this antenna. Approx 80kHz of 80m, 250kHz of 40m, and full band on
30/20/15 and 10 with SWR 1.5.

An added bonus might be that the SWR on 12m is 1.3, so it looks like I
have a HF7V now.

Excellent! I might go try that on mine.

- 73 de Mike KB3EIA -