> Looking at the J-Pole, I have to admit that I don't
> understand how it can work. It seems that the coax
> center and coax shield are shorted with a U shaped
> current path ...

RF behaves quite differently than DC.
If you put DC across the center & shield, indeed, you'd have a short and you'd 'shortly' begin to have smoke coming from either the antenna or the power supply(!).

However, to RF, the short, the 'U'section and the feedpoint are all part of the MATCHING section of the J-Pole antenna.

You want to put the center & shield on the j-pole at a point where the impedance works out to a perfect match with your coax and radio (i.e. 50 ohms) at that frequency.

With a suitably broadband j-pole, your match will deviate a bit from 50 ohms as you tune up and down but will not go far enough to increase the amount of mismatched RF going BACK to your radio (i.e. SWR should stay close to 1.1:1 ).

If you take a look at Cebik - http://www.cebik.com/vhf/jp1.html - you can actually see that the RF Current is at it's highest IN that 'U' point where the ground exists.

I'm sure I've made some mistakes in my explanation. Any errors are my own.

73
Mike Yancey
KM5Z
Dallas, Texas

Also, give Ham Radio Deluxe a try. It's a great,
comprehensive program.

It has a digital program, Digital Master 780
which is very good: PSK31, RTTY, Olivia,
CW (both regular keying and 'modulated SSB')

http://hrd.ham-radio.ch/DM780/DM780.htm

I just built an interface for CAT+DATA for my
FT-897D too. Runs great.

Mike Yancey
KM5Z
Dallas, Texas

LOL - this is sooooo true.

I can't understand why use a 3 syllable word

ki-lo-watt

instead of a 2 syllable word

ki-lo

I always use the standard, even if the other person
persists in using the 'oddball'.

Here's an excellent Wikipedia article about the
NATO Phonetic Alphabet, and includes some info
on 'alternates':

http://en.wikipedia.org/wiki/NATO_phonetic_alphabet

Mike Yancey
Kriegspiel-Marguerita-Five-Zapruder

I've been wondering this myself!

I also have a G5RV-JR (half-size, 52' long) up about
20 feet, over my aluminum roof. It's on the east side
(over the eastern roof slope, running N-S) so I
definitely get better eastern / east-coast results,
but I still get strong signals from CA, AZ, etc. I
also have good reports from Venezuela, Baja, Mexico,
and to the UK.

My furthest DX to date (just a couple of weeks ago) is
northwestern Italy, 20m SSB, 100W, so I'd be very
curious just how my roof is affecting the antenna.

By all rights it should be absorbing. But I'm thinking
this might be true at certain frequencies, and not at
others.

As mentioned in this thread - go with it and see what
happens.

73
Mike Yancey
KM5Z
Dallas, Texas

Universal Radio also shows this model as discontinued.

http://www.universal-radio.com/catalog/hamhf.html

I'd say if they were exiting the business they'd exit
the business. Perhaps they're paring down their
offerings and preparing for the future.

I'd heard that Kenwood was going either make or second
source Icom's D-Star in a transceiver, although that
model is still Japan only. Can't be more 'in the now'
than D-Star.

Mike Yancey
KM5Z
Dallas, Texas

>I have had some self proclaimed experts tell me that
>you do not really need a 4:1 balun when interfacing RG8
>coax to the standard parallel line that is attached to
>the antenna. I use a 4:1 current balun but was just
>curious.

Check out the OM himself in 'The G5RV Multiband Antenna... Up-to-Date' at:

http://www.arrl.org/members-only/tis/info/pdf/acv1086.pdf

Quote: "The main reason for not employing a balun in
the G5RV... the balun cannot compensate for the
reactive load... whereas a suitable type of matching
network can do this most effectively and efficiently'.

The G5RV (and half-sized and double-sized) must be
used with a Tuner (i.e. Antenna Match). You will need
a choke, not a balun, at the COAX-To-Parallel
interface to reduce RF from the outer side of the
coax. This is easy - you can just wind some coax like
you would a coil of rope - about 10 to 12 inches in
diameter.

I recently redid mine to tidy it up a bit - as you can
also wind a few feet on a one foot section of 4 inch
or 8 inch diameter PVC. Works pretty much the same.

I use a half-sized (52') G5RV and I just got my
farthest contact so far in Northwest Italy from
Dallas, Texas with 100 watts.

73
Mike Yancey
KM5Z

> How about a link for this fix?

The repair is in a beta version - which is actually quite stable! - so I'm not sure the 'auto upgrade' feature would notify.

In any case, the link is here:

http://www.ham-radio.ch/kits/beta/3.5/

At this moment, today, the latest is Beta 1584:

http://www.ham-radio.ch/kits/beta/3.5/1584/

But that might change at any time.

No need to uninstall - just install the beta over your current version. There are quite a few new features.

73
Mike Yancey
KM5Z
Dallas, Texas

MFJ seems to have an updated version of the chip and the manual details all the connections to it:

http://www.mfjenterprises.com/products.php?prodid=CK-8045ABM

(or query for 'Curtis').

Mike Yancey
KM5Z
Dallas, Texas

From my experience - and I've only used LinkSys wireless routers - there is a menu item to list all the machines that have an IP 'lease', or rather, have been on in the last 24 hours. You could check that periodically - only your machine names should be listed.

In addition, there is an inbound and outbound log that you can enable (inbound or outbound to the internet connection) and the outbound log also could disclose whether someone has been using your network.

There are other security options you can put into effect (again, only from my experience with LinkSys, but probably other mfrs provide similar options) -

1. limit the number of machines that can login to your network.
2. limit the router to allow ONLY the mac addresses (i.e. the Network Adapter hardware addresses) allowed on your machine. This would discourage all but the most savvy folks (who would clone your hardware addresses).
3. I believe some routers allow you to turn on and off wireless access based on time-frame - i.e. only when you're home (after 5 'til before 1:00 AM, or whatever your surfing habits).

Finally - you can change your WEP password occasionally and change the wireless channel occasionally - this would discourage the casual abuser.

Also, distance would limit access. I sometimes have a hard time accessing my OWN wireless from the front of the house...

73
Mike Yancey
KM5Z
Dallas, Texas