Re: KAT500 Remote Version

Posted by Don Wilhelm-4 on Sep 20, 2012; 9:03pm
URL: http://elecraft.85.s1.nabble.com/KAT500-Remote-Version-tp7563017p7563033.html

David,

Those who have mentioned "tuner loss" may or may not be correct - it all
depends on the tuner.  If the tuner is of the "T match" variety, it will
have multiple points where it can show a match, but many of those
"matched" points will result in high circulating currents in the tuner
and high losses.

Elecraft tuners are "L-match" tuners, and do not suffer from those false
tuning points - it will either match the load or it will fail.

You LMR600 coax is very low loss and at frequencies below 30 MHz. I
would offer that a 100 foot run could have an SWR as high as 5:1 and the
loss would be acceptable.  If your coax run is longer than that, or your
SWR is higher, then, yes, I would feel more comfortable with a remote
antenna tuner to keep the SWR on the coax down to a reasonable level.

73,
Don W3FPR

On 9/20/2012 3:59 PM, David Bunte wrote:

> I have been trying to decide between the KAT500... and a remote tuner at
> the base of my 30' vertical.  I have measured the SWR on each band, at the
> shack end of my 125' of LMR600.  If I take that length, frequency and SWR
> information and plug it into the chart for SWR loss of LMR600, I can see
> what my loss is on each band... but I am not sure that tells the entire
> story.
>
> Intuitively it seems that I want the ATU as close to the antenna as
> possible.  I could shorten my feedline to about 65'.  I could mount an ATU
> just inside my basement at about 30' from the antenna (and avoid a
> weatherproof box - as long as the ATU does not need to be seen or touched),
> or I could mount it at the base of the antenna, but that would be very much
> more challenging.
>
> Is the SWR loss, based on my cable type, length & frequency all I need
> consider, or am I missing something?
>
> Some people have told me that I need consider nothing else... others have
> said that "tuner loss" is critical, and that will be greater than the line
> loss.  That sounds bogus to me, but I really don't know.
>
> I also know that the ATU in my K3 can make the rig very happy on 80 through
> 6 with this antenna and 125' of cable... but I don't know if matching the
> antenna at the end of 1', 30' or 65' will be harder, or easier.
>
> It was suggested that the TLW program by N6BV, that is packaged with the
> ARRL Antenna Book would help, but I have not been able to figure out how to
> use it, and can find no instructions for that program.
>
> Any and all help will be appreciated.
>
> Dave - K9FN
>
>
>
>
>
> On Thu, Sep 20, 2012 at 2:50 PM, Wayne Burdick <[hidden email]> wrote:
>
>> It may be possible to remote the KAT500 with additional control
>> firmware and an appropriate weather-proof enclosure. We haven't done
>> any testing of this idea yet, but once we start shipping KAT500s,
>> we'll work with a few customers who want to experiment with this to
>> see what we can do to facilitate it.
>>
>> 73,
>> Wayne
>> N6KR
>>
>>
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