[Elecraft] TxMon and K3 (tuner bypassed) SWR missmatch

[Fred Jensen]

On 11/6/2016 11:06 AM, Ron D'Eau Claire wrote:
> Sri Jim: You must have misunderstood. You defined the rig as the 'load' so I
> used your definition. Perhaps that's the problem.

I thought that too.  Jim was here for dinner last night but I forgot to 
ask him.

> You are right; the antenna is usually up in the air, and some hams climb
> towers to make the adjustments at the antenna in order to ensure a good
> impedance match with the transmission line to minimize transmission line
> losses.

Well, except mine at home.  It's an EF 80-10 wire strung along the top 
of the 6' fence.  I can "measure" the SWR anywhere on it I want to since 
I'm 6'2" tall. :-)  While its claim to fame is being HOA-proof, its 
doing a surprisingly good job on 20 and 15 this AM in SS.  Just S&P as 
fresh meat on Sun AM, but almost no IMI's.

If you're willing to cut a 180 deg length of low-loss transmission line 
for the band(s) in question, you can measure the characteristics at the 
elevated antenna.
>
> But most of us with dipoles, etc., make do with an approximate match based
> on physical measurements. We measure the SWR at the rig to reassure
> ourselves that the SWR at the antenna is reasonable.

It it's at the minimum at the rig, it's at the minimum at the antenna 
too, even if the actual value may be different because of transmission 
line loss.
>
> And, of course, if the rig is not equipped with an ATU, we are concerned
> that the SWR at the rig is not high enough to be reduce final amplifier
> efficiency and increase heat dissipation. That was the original concern that
> started this thread.

Indeed

73,

Fred K6DGW
- Sparks NV DM09dn

- Northern California Contest Club
- CU in the Cal QSO Party 7-8 Oct 2017
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