[Elecraft] NOT the feedline

[Mark Goldberg]

I failed to mention, my antenna system is a 300 ft long horizontal loop fed
by ladder line with a homebrew two core switchable 1:1 or 4:1 Guanella
current mode Balun. The Balun has a measured return loss of about 32 dB at
50 MHz with a 200 ohm resistive load. That was surprisingly good, but
confirmed with a calibrated VNA. Yes, I spent some time with Jerry Sevick's
book.

The antenna is not deluxe for 50 MHz, but it is all I have. It's just so
happens that only small values are required in the tuner to match it, and
the LDG tuner parasitic capacitance it too high even when in bypass mode. I
expect it is difficult to build a physically large high power tuner and
keep the parasitics down, so the Ten Tec may have similar issues. As I
said, I know nothing about it. From Peter's most recent email, this may be
the case.

73,

Mark
W7MLG

On Tue, Jun 2, 2020 at 8:26 AM Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:

> As a rule, if one needs a tuner to get a good match on 6M, I'd say they
> need to look carefully at their antenna system.  My 6M yagi shows less than
> 1.5:1 over the lower 2 MHz of the band, 50.0 - 52.0 MHz.  The lowest SWR
> occurs at 50.2 with a Z value of 42 ohms and an X value of 0.0.  Of course
> higher gain antennas typically have a bit less bandwidth, but still, the
> lower 1 MHz should be totally usable without a tuner.
>
> Besides, tuners only make the transmitter happy and the added feed line
> loss due to SWR still remains.
>
> 73
>
> Bob, K4TAX
>
>
> On 6/2/2020 1:09 AM, Mark Goldberg wrote:
>
> I want to mention that my LDG AT-600Pro has a minimum capacitance that is
> too high for a good match to my antenna on 6 meters. Certainly seems like
> removing the Ten Tec tuner would be a good thing to try. Can you open the
> Ten Tec tuner and use an IR thermometer to monitor the components? I don't
> know anything about it's construction. You could see them heating up.
>
> Just running medium power of maybe 500W would slow things down and let you
> see the SWR increasing before the amp trips. That would confirm that
> something is heating up vs arcing.
>
> 73,
>
> Mark
> W7MLG
>
>