[Elecraft] K1 and Z match tuner questions

[Don Wilhelm]

Bob,

Your LED swr meter is showing when you have a low SWR on the transceiver to
tuner coax.  The K1 indicator is showing you the RF voltage - the two are
not the same.  Do not attempt to tune the antenna tuner using the indicator
on the K1 - a higher RF Voltage can simply be the result of a greater
mismatch.

Your LED SWR meter is not sensitive a low levels of SWR (below about 1.3)
because of the diode effects, but it will get you into the range where the
K1 can feed the coax properly with little power reduction.

If you want to adjust the tuners for the greatest output, you will have to
put an RF detector at the tuner output - and even if you do that, do not
adjust very far from the point where the tuner LED indicates a low SWR or
things will get 'out of whack' (precise engineering term <G>).

73,
Don W3FPR


> -----Original Message-----
> Hello everyone,
>
> I have a ZM-2 and a BLT tuner which I connect to an end fed wire of 33
> feet length. Most of the antenna is outside, but it is only 10 feet
> above ground. I am using an inside  counterpoise of 23 feet, mainly for
> 30M and works well on 40M too. The K-1 is for 20/15M.
>
> I notice that if I adjust either of the tuners for minimum LED
> brightness on 20M (the light does not go completely out) that the LCD
> on the K-1 shows one hatch mark when the key is closed. If I hold the
> key down and adjust the tuner without regard to the LED I can easily
> get the LCD to show 4 hatch marks.
>
> Could it be that the Z matches are so sensitive that "LED out" means
> 1:1 swr ratio and "on" means perhaps 1:1.3, etc.  and "bright" means
> anything?
>
> Can I safely and to good effect tune the radio by hatch mark and ignore
> the LED?
>
> Why do you suppose the K-1 and Z matches don't agree?
>
> TNX for advice.
>
> Bob
> N5JYW
> Wisconsin
>