[Elecraft] [K1] Question about antenna tuners that I should not have to ask but do.

[Doug Person]

Sounds like a great use for a remote tuner. (sure wish Elecraft would 
develop one).  I have an LDG Remote Tuner for tuning a 44' doublet in 
the attic of my town home.  Works great. 40 through 10 with acceptable 
SWR.  (unfortunately for me the noise floor isn't a floor - it's a 
skyscraper).

Doug -- K0DXV

On 9/28/2015 6:24 PM, Byron Servies wrote:
> Sorry, I should have said "none" instead of "1:1".  You don't appear to need it.
>
> I also have a very compromised installation, but better now than a
> dipole. And, yes, a tidy installation does us a shocking amount of
> coax!
>
> Good luck,
>
> 73, Byron N6NUL
>
> On Mon, Sep 28, 2015 at 5:02 PM, Byron Servies <byron at n6nul.org> wrote:
>> On Mon, Sep 28, 2015 at 4:37 PM, Douglas Hagerman
>> <douglas.hagerman at me.com> wrote:
>>
>>> I have a space-limited dipole for 20 meters with drooping ends. The KAT-1 tuner
>>> will tune it. What I want to know is whether to use a 4:1 or 1:1 balun, or no balun,
>>> at the antenna.
>>>
>> Are you feeding the antenna with coax or ladder line?
>>
>> Even a low dipole will have a feed point impedance of roughly 75 ohm,
>> so 1:1 would be fine with coax.  You may want to consider a current
>> choke at the feed point, but that's up to you.
>>
>> With 450 or 300 ohm ladder line, a 4:1 would be more appropriate to
>> match the feedline to the expected impedance of the K1 input.
>>
>>> If the tuner reports 24 “x10” pF, is that 240 pF or 2.4 pF? A straight reading
>>> suggests that it’s 2.4 pF, but I don’t see how the tuner circuit can provide so
>>> little capacitance. But C4 (82 pF) plus C5 (150 pF) gives 232 pF which could
>>> 240 pF if you include some parasitic capacitance, maybe?
>> Xc = 1/(2 * pi * 14 x 10^6 * 240 x 10^-12) ~~ 47.
>>
>> So, the tuner thinks it is seeing roughly 50 + j47 and needs -47 of
>> capacitance to balance it out, right?  I'd go with the 1:1.