[Elecraft] AX1 works great

[Rick nk7i]

Jim,

I stand by what I said (and we don't disagree, it's semantics). For 
further (group, noob) understanding; an improved definition...

A 'tuner' is a variable impedance matching network; interfacing the 
input impedance to the output impedance to allow the most possible flow 
of energy between them.  (Too many words for a noob.)

It doesn't need to take into consideration of the impedances along the 
feed; it matches what it gets (as best it can).

It does zip for any antenna except (once adjusted correctly) allow the 
most energy between input and output of the tuner to be exchanged.

THAT is the main benefit, more throughput while the secondary benefit is 
less heat and longer life from an 'irritable' RF power source (i.e. 
transistors) from mismatch.  [You cannot expect long life of any final 
of any kind at high power into a gross mismatch of impedance load.  Some 
devices allow you to learn instantly😮, that you've made a mistake; 
others take time to inform you.]

A tuner does NOT make any antenna more efficient; it makes it louder 
because the max energy is exchanged.  Antenna efficiency, involves a few 
more aspects not covered here.

WHAT impedances are  being matched, depends on where the tuner (or even 
fixed tuned circuit) is placed; at the antenna is usually optimal (less 
feed losses); but it can be at any place along the path between rig and 
antenna; making the downstream feed, part of the antenna network (some 
designs require that feed for impedance matching).  (Rig internal 
tuners/matching are still AFTER the final.)

I too recall the tube days where one loaded the rig into a 50 ohm dummy 
load for max output (peak, dip, repeat) then into a tuner (repeat the 
same process on the tuner elements); where it went into the entire 
antenna network (which was almost any impedance in those days).  [I 
still have that rig, but it's been so long without power, it could be 
'exciting' to apply power now.]

And in those days, I also came up with configuration of (unboxed, open 
on a board, DO NOT TOUCH the parts) tuner and antenna that 200 watts 
went in and nothing reached the antenna (connected directly to the 
tuner); but it sure warmed the room nicely (happy tube rig AND tuner 
warmed up).  "Why am I not being heard?"  hi hi...  Yep the tuner 
happily absorbed ALL the output of that rig (a Knight as I recall).

I do not miss those days but they did teach (sometimes painfully).  I'm 
much happier with power on (boot) the (no tube) rig while the antenna 
tunes (in the case of a SteppIR, it actually tunes, is always resonant) 
and turns to the location direction I wish to work.  Simpler, just ROCKS.

By the time the station has done those things (for me); I have the 
refreshment at hand, seat adjusted then... get to work.

73,
Rick nk7i



On 9/30/2024 2:10 PM, Jim Brown wrote:
> On 9/30/2024 1:39 PM, Rick nk7i wrote:
>> In the simplest sense, what a tuner does, is (attempt to) adapt the 
>> impedance of the antenna to that of the source so that the max energy 
>> is exchanged between the two (what works for TX, works for RX).
>
> Hi Rick,
>
> I disagree with this analysis and that proposed by AB7E, primarily 
> because it ignores the match between the antenna feedpoint Z and the 
> transmission line, which is what determines voltage and current 
> distribution along the line, and its loss. The tuner does NOT change 
> that.
>
> What a tuner does is transform the antenna's impedance as seen at the 
> shack end of the line to a value that the transmitter's output stage 
> can supply power and operate optimally. For most modern transmitters 
> and solid state amps, that's 50 ohms resistive.
>
> Those of us long enough in the tooth to remember hollow-state 
> amplifiers and output stages may have learned that they come equipped 
> with variably tuned output networks to do what antenna tuners do, but 
> usually over a much less-wide range.  My Ten Tec Titan 425, 1978 
> vintage, could be happy with mismatches in the range of 3:1. Ten Tec 
> sold one of the best (greater efficiency over a wider range) tuners to 
> cover a much wider range.
>
> BTW -- I know that you know all this stuff -- this post is for those 
> who don't. :)
>
> 73, Jim K9YC
>
>
>
>
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