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KAT1 disappointment

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wrmoore

KAT1 disappointment

Just completed my KAT1 for my K1 that I finished last night. All the tests
seem to work properly, and I get a r1.0 (SWR of 1.0) on all 4 bands (7, 10,
14, & 21 MHz) when transmitting into a dummy load. However, when
transmitting into my attic dipole the KAT1 can only achieve a match on 14
and 21 MHz (1.3 and 1.2 respectively). On 7 MHz I get r4.1 as best match,
and on 10 MHz I get r3.2, both after much rattling of relays. My K2 (which
I realize has a greater matching range) has no trouble with the same antenna
setup.

The rigs are connected with about 2 ft. of RG58 to a 4:1 LDG balun, then to
maybe 30-40 ft. of 450 ohm ladder line out into the attic where I have a
40m. 1/4 wave dipole with the center at the peak of the roof and the ends
drooped down in random ways to fit the available space.

When I adjusted C9, by the way, I got a null of about 0.06 mv.

As I said, I've been through all the tests on the KAT1, including trying
each L and C individually to make sure they are all working, and everything
looks good. So I'm guessing I have to do something to the antenna to get
make things work. Perhaps play with the length of ladder line? Any
suggestions would be welcome.

73,
Randy, KS4L

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wrmoore

RE: KAT1 disappointment

One other thing. When, for example, I tune on 14 MHz, then tune on 21 MHz,
then return to the same frequency on 14 MHz, the tuner doesn't seem to
remember the 14 MHz setting. The relays clatter a while as the algorithm
re-finds the best SWR. Is that right???

> Just completed my KAT1 for my K1 that I finished last night.
> All the tests seem to work properly, and I get a r1.0 (SWR
> of 1.0) on all 4 bands (7, 10, 14, & 21 MHz) when
> transmitting into a dummy load. However, when transmitting
> into my attic dipole the KAT1 can only achieve a match on 14
> and 21 MHz (1.3 and 1.2 respectively). On 7 MHz I get r4.1
> as best match, and on 10 MHz I get r3.2, both after much
> rattling of relays. My K2 (which I realize has a greater
> matching range) has no trouble with the same antenna setup.
>
> The rigs are connected with about 2 ft. of RG58 to a 4:1 LDG
> balun, then to maybe 30-40 ft. of 450 ohm ladder line out
> into the attic where I have a 40m. 1/4 wave dipole with the
> center at the peak of the roof and the ends drooped down in
> random ways to fit the available space.
>
> When I adjusted C9, by the way, I got a null of about 0.06 mv.
>
> As I said, I've been through all the tests on the KAT1,
> including trying each L and C individually to make sure they
> are all working, and everything looks good. So I'm guessing
> I have to do something to the antenna to get make things
> work. Perhaps play with the length of ladder line? Any
> suggestions would be welcome.
>
> 73,
> Randy, KS4L

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wayne burdick

Re: KAT1

Administrator

In reply to this post by wrmoore

On Jun 21, 2006, at 7:07 PM, Randy Moore wrote:

> Just completed my KAT1 for my K1 that I finished last night. All the
> tests
> seem to work properly, and I get a r1.0 (SWR of 1.0) on all 4 bands
> (7, 10,
> 14, & 21 MHz) when transmitting into a dummy load. However, when
> transmitting into my attic dipole the KAT1 can only achieve a match on
> 14
> and 21 MHz (1.3 and 1.2 respectively). On 7 MHz I get r4.1 as best
> match,
> and on 10 MHz I get r3.2, both after much rattling of relays. My K2
> (which
> I realize has a greater matching range) has no trouble with the same
> antenna
> setup.

Randy,

It's true that the KAT1 has a smaller reactance range than the K2. This
was unavoidable given the limited PCB real estate.

Assuming all the L and C components are installed correctly, there are
several things you can do to effectively increase the matching range.
Here are the things I'd try.

1. Use a 1:1/4:1 balun with a switch (like the BL2). There are times
when this will transform the impedance to advantage on one or more
bands.

2. Short the twinlead wires together, and connect the two wires
directly to the KAT1's hot lead. Make sure the K1's chassis is grounded
at the antenna jack or elsewhere. This turns the system into a random
wire or sorts, and again this may allow easy matching on some bands.

3. Adjust the length of the twinlead or of the dipole itself by a few
feet at a time. Apparently on 40 and 30 m the reactance is a lot higher
than expected, and by adjusting the length a bit, you can sometimes
move away from very high- or low-impedance points.

Also note that the K1 is reasonably well protected against high SWR.
You can safely use it into high SWR, although you might be down a dB or
two at 4:1 depending on how the transmitter feels about the situation
:)

Let me know if any of these suggestions help.

73,
Wayne
N6KR

---

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Bob Cunnings NW8L

Re: KAT1 disappointment

In reply to this post by wrmoore

Maybe, for your line length, the 4:1 transformation is putting the
feedline input Z out of range of the K1 tuner on 40 and 30. It might
be fun to try switching to a 1:1 balun (or no balun at all) to just to
see what happens... since it's so easy to do. Beyond that,
experimenting with feedline length seems like the next step.

Bob NW8L

On 6/21/06, Randy Moore <[hidden email]> wrote:

> Just completed my KAT1 for my K1 that I finished last night. All the tests
> seem to work properly, and I get a r1.0 (SWR of 1.0) on all 4 bands (7, 10,
> 14, & 21 MHz) when transmitting into a dummy load. However, when
> transmitting into my attic dipole the KAT1 can only achieve a match on 14
> and 21 MHz (1.3 and 1.2 respectively). On 7 MHz I get r4.1 as best match,
> and on 10 MHz I get r3.2, both after much rattling of relays. My K2 (which
> I realize has a greater matching range) has no trouble with the same antenna
> setup.
>
> The rigs are connected with about 2 ft. of RG58 to a 4:1 LDG balun, then to
> maybe 30-40 ft. of 450 ohm ladder line out into the attic where I have a
> 40m. 1/4 wave dipole with the center at the peak of the roof and the ends
> drooped down in random ways to fit the available space.
>
> When I adjusted C9, by the way, I got a null of about 0.06 mv.
>
> As I said, I've been through all the tests on the KAT1, including trying
> each L and C individually to make sure they are all working, and everything
> looks good. So I'm guessing I have to do something to the antenna to get
> make things work. Perhaps play with the length of ladder line? Any
> suggestions would be welcome.
>
> 73,
> Randy, KS4L
>
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>

Bob Baxter-4

Re: KAT1 disappointment

Bob Cunnings wrote:
> Maybe, for your line length, the 4:1 transformation is putting the
> feedline input Z out of range of the K1 tuner on 40 and 30. It might
> be fun to try switching to a 1:1 balun (or no balun at all) to just to
> see what happens... since it's so easy to do. Beyond that,
> experimenting with feedline length seems like the next step.

To see how feed line length effects tuning see
<http://www.qsl.net/w5dxp/notuner.htm> (as mentioned in a previous
post) An antenna analyzer really helps but the 4SQRP club's
"Tenna-dipper" is a cheaper alternative, if its still available.

Bob Baxter aa7eq
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