[Elecraft] Tuning Random-Length Wire Antenna with K3 Internal Tuner??

[Walter Underwood]

I think you just proved my point. The KAT3A does not have a lower power rating for larger SWRs. That would indicate that it can handle the rated power over the entire rated SWR range. If extreme SWR at full power would exceed the component ratings, the specs would say that.

This is the entire set of specs for the KAT3A:

	• Maximum impedance match:  10:1 SWR
	• Maximum power handling:  110 watts

https://elecraft.com/collections/kat3a_model/products/kat3a-100w-atu

I just curious why people would think that Elecraft publishes specs that their equipment does not meet. That is a pretty strong accusation.

No, I didn’t check out TLW, but I have a solid understanding of transmission lines and conjugate matches, even though I only got a B- in my fields and waves class at Rice.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Dec 12, 2020, at 11:12 PM, David Gilbert <ab7echo at gmail.com> wrote:
> 
> 
> Seriously??  Why do you think that Elecraft's tuners (like just about every other one) have max power ratings that differ depending upon the SWR?  For example, for the KAT500 has a max power rating of 1000 watts into a 3:1 SWR but only a 600 watt rating into a 10:1 SWR???  It can match both SWRs, but not handle the same power at both.
> 
> Did you bother to check out TLW like I suggested?
> 
> Dave   AB7E
> 
> 
> 
> On 12/12/2020 8:59 PM, Walter Underwood wrote:
>> Of course there are high voltages or currents in some tuning solutions. Why do people think the Elecraft ATU would not be designed to handle those?
>> 
>> wunder
>> K6WRU
>> Walter Underwood
>> CM87wj
>> http://observer.wunderwood.org/ (my blog)
>> 
>>> On Dec 12, 2020, at 7:36 PM, David Gilbert <ab7echo at gmail.com> wrote:
>>> 
>>> 
>>> A matched conditon does NOT prevent the components of the tuner from seeing high voltages and/or high currents.  Check out TLW ... the transmission line application that comes free with the ARRL Antenna Book.  Pick a load that gives a high SWR and then click on the "Tuner" button for the application to draw one of four different tuner configurations for you.  The app will tell you what the voltages across each component are, and also the power loss (i.e., heating effects) in each one.
>>> 
>>> 73,
>>> Dave   AB7E
>>> 
>>> 
>>> 
>>> 
>>> On 12/12/2020 8:18 PM, Walter Underwood wrote:
>>>> Tuning happens at low power, so transients are small. After it is matched, why would the K3 ATU not be rated for full power over the full SWR range?
>>>> 
>>>> Other components might fail, of course. Amphenol UHF connectors are only rated for 500 V.
>>>> 
>>>> wunder
>>>> K6WRU
>>>> Walter Underwood
>>>> CM87wj
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