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KAT500 usage model?

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Jim AB3CV

KAT500 usage model?

What sort of feedline and antennas are folks expecting to use with the
KAT500?

I assume OPs want this because they are running more than a barefoot K3/100.

Are folks running 500w at elevated SWR on "normal" coax (e.g. davis bury
flex), open wire line or 7/8" hardline into the shack?

I assume that much of the 500w usage is into nominally resonant antennas.
What other types of non-resonant antennas are in use at this wattage level
that would need such a tuner in the shack?

Thanks

Jim ab3cv
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ke9uw

Re: KAT500 usage model?

I use a 1:1 balun into 4 inch open wire line to a 205 ft long dipole.

Sent from my iPad

On Jun 17, 2012, at 6:59 PM, "Jim Miller" <[hidden email]> wrote:

> What sort of feedline and antennas are folks expecting to use with the
> KAT500?
>
> I assume OPs want this because they are running more than a barefoot K3/100.
>
> Are folks running 500w at elevated SWR on "normal" coax (e.g. davis bury
> flex), open wire line or 7/8" hardline into the shack?
>
> I assume that much of the 500w usage is into nominally resonant antennas.
> What other types of non-resonant antennas are in use at this wattage level
> that would need such a tuner in the shack?
>
> Thanks
>
> Jim ab3cv
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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Chuck, KE9UW

Don Wilhelm-4

Re: KAT500 usage model?

In reply to this post by Jim AB3CV

Jim,

The answer to your question is steeped in the many requests for the
KAT500 - Each station has its own set of antennas. Some do have all
resonant antennas and do not need the tuner, but that does not seem to
be the majority - thus the demand for the KAT500. In the meantime, some
are using manual tuners or are restricting their operation to those
bands where their antennas are resonant.

I would suggest that the answers vary "all over the board". In my
particular case, I run resonant antennas due to an agreement with the
XYL when we married - she said she did not want to see antennas or
feedlines when coming up the driveway. That has been accomplished, but
at the expense of long feedlines (150 feet minimum, 220 feet typical),
so I keep the SWR low at the antenna field end of things and use
resonant antennas.

73,
Don W3FPR

On 6/17/2012 7:59 PM, Jim Miller wrote:

Jim AB3CV

Re: KAT500 usage model?

In reply to this post by Jim AB3CV

I should have added some context to my question. I'm considering adding the
KPA500 at some point. I currently have a hexbeam for 20-6m which has <1.5
SWR so I doubt the KAT500 would be a benefit there.

I currently have a non-resonant dipole for 80-30m which I occasionally use
as a hatted vertical. Both configurations are supported by a 125 remote
tuner under the feedpoint via a 50ft length of window line. The run to the
shack is 100ft of Buryflex.

I can see that the dipole configuration would require a remotable 500w
tuner if it remains. But I'm considering alternatives which won't require
putting the tuner outside. Resonant dipoles for 30m and 40m are a
possibility and perhaps a vertical for 80m. If alll were resonant I
wouldn't need anything other than an antenna switch to move among them.

Jim ab3cv
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k6dgw

Re: KAT500 usage model?

In reply to this post by Don Wilhelm-4

On 6/17/2012 5:17 PM, Don Wilhelm wrote:

> I would suggest that the answers vary "all over the board". In my
> particular case, I run resonant antennas due to an agreement with the
> XYL when we married - she said she did not want to see antennas or
> feedlines when coming up the driveway. That has been accomplished, but
> at the expense of long feedlines (150 feet minimum, 220 feet typical),
> so I keep the SWR low at the antenna field end of things and use
> resonant antennas.

Once I got the tower/tribander by Andrea and she stopped referring to it
as "Mission Control," the rest was easy. We're on 5 acres, it's way out
back, not really visible at all [try and find it on Google Earth]. But,
I like the lower frequency bands. I have lots of Organic Towers, all
poorly placed by the Organic Gardener, so I rely on a couple of
non-resonant wires for 160-40. With the baluns, the coax VSWR runs
around 1:1 to 2.5:1. The latter is too much for the KPA500, I'm really
fatigued cranking the MFJ tuner around and it doesn't work all that
reliably anyway, so the KAT500 is on order.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

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Dick Dievendorff

Re: KAT500 usage model?

In reply to this post by Jim AB3CV

In my last home I had a short (15' or so) coax from the ATU to a balun
outside, and ladder line from the balun to the center of an all-band dipole.
I found it much more convenient to run coax through the wall than ladder
line. I plan to duplicate this in my new home (under construction). I have
found an all-band dipole a great thing to have handy.

I'll be feeding a multiband vertical antenna (a HyTower) several hundred
feet my shack. I'm not yet sure if I'll use surplus CATV hardline or a
good-quality coax. The HyTower is resonant on some parts of the bands I want
to use, but it needs a little ATU help in some places. It's hard work to
cover all of 3.5 to 4 MHz (although broadband antennas exist).

Some commercial tuners with provision for a balanced line (like my
Nye-Viking MB-V-A) use an internal balun. I found it easier to put a balun
on the outside of the shack wall.

My older 40 meter antenna was cut for the CW end of the band, and when I
wanted to use it on phone I had to use the Nye-Viking for help. I was busy
in phone contests, working people split frequency. I've solved that in two
ways, I'm going to use a KAT500, and my new 40 meter antenna (a W6NL design
Moxon) is broad banded.

There are a good range of SWRs (e.g. 2:1) that don't introduce all that much
loss if the coax is good, the run isn't all that long, and the frequency
isn't that high. You lose a lot more power at high SWR on 2 meters than 80
meters.

I use N6BV's "Transmission Line for Windows" (TLW) software, which came with
my Antenna Book, to understand how much loss I'm going to suffer with
various transmission lines at various SWR values.

I am also inspired by Walt Maxwell's assertion in "Unimportance of Low SWR
Values" in his Reflections III, where he states, "From the viewpoint of
amateur communications, it can be shown mathematically, and easily verified
in practice, that the difference in power transferred through any coaxial
line with an SWR of 2:1 is imperceptible compared to having a perfectly
matched 1:1 termination".

I believe him, but my solid-state amplifier is happier at 1.5:1 than 2:1, so
I need to provide some impedance transformation help. In the shack, where
it's easy to change.

I'm not planning high SWR runs at a long distance unless I have better than
average coax transmission line. I've found some surplus 75-ohm CATV
hardline to feed that HyTower out in the woods. It'll present an impedance
mismatch right at the start. I don't care; the ATU will provide the
necessary transformation. And I also don't care what the ladder line SWR
is. I do worry about how the balun performs at high SWR.

I may also run 12V DC on the coax to the HyTower and switch in some lumped
reactance to help with the 80 meter phone/CW transition and perhaps some
similar help on 160. Haven't figured that out yet.

73 de Dick, K6KR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jim Miller
Sent: Sunday, June 17, 2012 5:00 PM
To: Elecraft Reflector
Subject: [Elecraft] KAT500 usage model?

> What sort of feedline and antennas are folks expecting to use with the
KAT500?

Jim ab3cv

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Jim Brown-10

Re: KAT500 usage model?

In reply to this post by Jim AB3CV

On 6/17/2012 4:59 PM, Jim Miller wrote:
> What sort of feedline and antennas are folks expecting to use with the KAT500?

I'm very much a fan of resonant antennas, and feed them with both 50 ohm
and 75 ohm coax, whichever is the best match to each antenna. I have
two fan dipoles for 80M and 40M that happen to have reasonably
acceptable SWR on 30M, 17M, 12M, and 6M. Both are fed with Belden
8213. Depending on what you're able to do at your QTH, that's an
antenna worth considering.

At my current QTH I have lots of space, but I didn't on my city lot in
Chicago. Even there I used resonant antennas on all bands but 160M,
where I did what you're doing -- feeding an 80/40 loaded dipole as a top
loaded vertical. I did the switching in the shack -- the feedline was
75 ohm twinlead (some VERY old Belden stuff called Kilowatt twinlead)
that I terminated on a Pomona (dual banana). One antenna tuner input had
a Pomona wired normally, the other had a Pomona that shorted both sides
of the feedline to the hot conductor.

Like Don says, each of us will do what works for our own antenna farm.

73, Jim K9YC
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Don Wilhelm-4

Re: KAT500 usage model?

In reply to this post by Jim AB3CV

Jim,

It sounds like you have a bit of space to work with, so let me suggest
my wire antennas that come into the shack on 3 feedlines (could be
reduced to 2 with remote feedline switching). One antenna is a
broadband 80 meter dipole (actually an inverted Vee) with its center at
48 feet. That antenna is featured in the ARRL Antenna Book 19th Edition
page 19-16. At right angles to the 80 meter elements are the 40 meter
elements giving me an 80 and 40 meter antenna that has less than a 2:1
SWR over the bands (OK. I lied a little, SWR goes to 2.3 above 2.9 kHz).
The second dipole is a set of parallel dipoles for 20, 15 and 10
meters. The 3 wires are separated by one foot using PVC supports for
the separators. The 3rd antenna is similar, but is a parallel dipole
for 30, 17 and 12 meters.

The net result is that antennas for all bands are 80 through 10 are
resonant, and a 3 way antenna switch is sufficient to access all of them.

If you want to expand to 160 meters and 6 meters, 2 more antennas and
feedlines are required - I would suggest an inverted "L" for 160 and
either a dipole or a beam for 6 meters, but that means 2 more feedlines.

Figuring out your antenna switching system when the number of feedlines
exceeds 3 is a challenge, and there is no one answer - it all depends on
your desires and your aspirations.

I have not addressed beams, but they can be injected into the
feedline/remote antenna relay/ in-shack feedline selection equation.

Personally, I have 3 HF feedlines running into the shack, and 3 VHF/UHF
feedlines. I have the 160/80/40 BC trapper and a GAP Titan vertical as
well. While the VHF/UHF system is currently incomplete, I should be
able to do both satellite and terrestrial VHF/UHF as well as HF antenna
selection from the shack when it is done. I have made several attempts
at automating that selection with the Elecraft KRC2 as well as
extensions and devices of my creation, but have fallen back to manual
selection of the antenna. In contest stations, quick and easy and
non-ambiguous antenna selection is important, but not so for my station
- I have installed enough indicators to tell me what relay should have
been activated, and if the SWR indicates something other than what is
expected, I know that something along the way has failed - give up that
band for today and troubleshoot tomorrow.

If anyone is interested in my in-shack switching system that allows
the priority one transceiver to taqke one feedline, and a 2nd
transceiver to take a 2nd feedline, leaving the 3rd feedline for a 3rd
transceiver, I will send the rough sketch schematics to you - just
ask. The switches have many poles that make that selection possible and
were salvaged from RS-232 or DB-25 switch boxes.

73,
Don W3FPR

On 6/17/2012 8:33 PM, Jim Miller wrote:

> I should have added some context to my question. I'm considering adding the
> KPA500 at some point. I currently have a hexbeam for 20-6m which has <1.5
> SWR so I doubt the KAT500 would be a benefit there.
>
> I currently have a non-resonant dipole for 80-30m which I occasionally use
> as a hatted vertical. Both configurations are supported by a 125 remote
> tuner under the feedpoint via a 50ft length of window line. The run to the
> shack is 100ft of Buryflex.
>
> I can see that the dipole configuration would require a remotable 500w
> tuner if it remains. But I'm considering alternatives which won't require
> putting the tuner outside. Resonant dipoles for 30m and 40m are a
> possibility and perhaps a vertical for 80m. If alll were resonant I
> wouldn't need anything other than an antenna switch to move among them.
>
> Jim ab3cv
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Jim AB3CV

Re: KAT500 usage model?

In reply to this post by Jim AB3CV

Thanks for all the good ideas and food for thought. I'm currently in a HOA
situation on a 1 acre lot the back 1/4 of which is wooded. I got my license
a couple of years after I bought the house. Those woods provide the stealth
for my dipole and hexbeam. Not a lot of room for exotic setups but I'll
work something out.

Thanks again!

jim ab3cv
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Jim Brown-10

Re: KAT500 usage model?

On 6/18/2012 8:47 AM, Jim Miller wrote:
> Those woods provide the stealth
> for my dipole and hexbeam.

Great. Some of my antennas are in the woods. Dark colored wire and
relatively small wire can be pretty stealthy. The black rope sold by Ham
Radio Outlet is pretty strong and also quite stealthy. Be careful with
this rope strung over tree limbs though -- it can fray as the trees move
in the wind, and will eventually break.

My towers in the woods are painted a dull brown color, and I've wound
black tape around the boom of my SteppIR. If you want to bury coax, go
to Davis Buryflex. It's also OK to drape coax over to a tree and bring
it down next to the trunk, or to use a short length of smaller coax to
get down to the ground and then transition to larger coax for the rest
of the run to minimize loss.

73, Jim K9YC
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