[Elecraft] [OT] High SWR on 20 and 40

[Don Wilhelm]

Brian,

While all that is true, the operating convenience that is afforded by 
using that method can be more significant than the added loss - it all 
depends...

An L network usually is a low loss tuner.  All the Elecraft tuners are 
of the L network type, as are many other 'auto-tuners'
The old link coupled tuners such as the Johnson Matchbox are also very 
low loss.  The popular "T" networks can be very bad with multiple 
matching points, but they do have a very large range and bandswitch easily.

Using a manual tuner to bring the SWR on a difficult to feed antenna 
down to a reasonable level and then refining the match with an internal 
auto-tuner provides the same convenience as operating with only the 
autotuner - and the manual tuner can be in a remote location.  After 
all, matching networks at an antenna can be thought of as "manual tuner" 
whose tuning is not changed - it brings the impedance down to a level 
where it can be easily fed with coax, and a tuner in the shack provides 
the final match required for large excursions across the band.

Yes, at HF, an SWR of 2:1 or less does not increase the coax loss enough 
to be significant.  At VHF and UHF it does make a difference because the 
additional loss caused by SWR grows as the matched line loss increases, 
and matched line losses increase with increasing frequency.

73,
Don W3FPR

Brian Alsop wrote:
> Of course two tuners doubles the tuner losses.  Tuner losses amount to 
> 10 to 15% per tuner, sometimes higher.  If you're not folding back power 
> after the first tuner does its match and it's under about 1.8, don't 
> bother.  There is nothing real to be gained.
>
> If you need both tuners, the real need is for a better matched antenna 
> or a single tuner with a wider matching range.
>
> 73 de Brian/K3KO
>
>
> Don Wilhelm wrote:
>   
>> Dave and all,
>>
>> Are you aware that you can use both tuners "in tandem"?  You can set the 
>> manual tuner quickly for a close match and then let the internal tuner 
>> refine the match.
>>
>> For instance, you have an antenna that is difficult to match, but you 
>> already have a list of setting for a close match (less than 3:1) on the 
>> manual tuner for that antenna - just turn to those settings and then let 
>> the KX1, K1, K2, K3 tuner clean up for a very ow SWR.
>>
>> 73,
>> Don W3FPR
>>
>>     
>>> The bottom line for me is that the KX1 ATU is useful, but not very wide 
>>> ranging.  It may work better on some other types of antennas.  I'm glad I 
>>> have it, but some situations probably require an outboard unit that is more 
>>> versatile.  Since I use balanced feedline type antennas a lot when I am 
>>> portable, I usually have an outboard tuner for that reason.  I really like 
>>> "Z" match tuners for QRP use.  The NorCal BLT is a good one too.
>>>
>>> Dave W7AQK
>>>   
>>>
>>>       
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>
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