[Elecraft] KX3 External Transverter and ATU TUNE disable optionsuggestion

[David Anderson]

Don,

That makes sense too, thanks.

I still would like to have an option of a tap off the low power drive before the PA with the PA disabled when using an external transverter, so that I could have the benefit of controllable low power with low wideband transmitted noise and no heat problems at high duty cycle.

73

David Anderson GM4JJJ




> On 5 Jan 2014, at 20:17, Don Wilhelm <w3fpr at embarqmail.com> wrote:
> 
> David,
> 
> I don't know about the power control characteristics of the KX3 yet, but with the K2 without the K60XV option), more steady power control is achieved in the 2 to 10 watt range as compared to lower power levels.  It all has to do with resolution - the power is set in 0.1 watt increments, and an uncertainty of 1 count can double or halve the power level at very low values, but that same uncertainty is much less at 2 watts and even less at 4 watts.
> 
> For JT65 and other long transmission full duty cycle periods, the heat dissipation must be considered if you want to prolong the life of the finals - so use 2 or 3 watts.
> 
> 73,
> Don W3FPR
> 
>> On 1/5/2014 2:42 PM, David Anderson wrote:
>> David,
>> 
>> I have a further thought about the difficulties of using the KX3 with an external transverter, if we reduce the maximum power output for the XVTR by using the XV PWR H setting to say a very low value (say the lowest which is 0.1 Watt), then is there a danger that the relative transmitted wideband amplifier noise will be higher than if we kept the power at say 4 Watts and then used a big attenuator on the input of the TX port on the transverter?
>> 
>> All my previous experience with transverters have been with radios that had dedicated low power transverter RF out ports. Even then there were problems with thermal power drift, excessive drive levels due to lack of the normal ALC that radio normally depended on when using it on HF etc.
>> 
>> I presume that there is no way to easily bypass the PA and driver stages within the KX3 to get lower drive power without reducing the TX gain. I have been looking at the KX3 schematics trying to work out where the as yet unreleased KX3 internal 2m transverter gets it drive from and at what level that is.
>> 
>> Perhaps Elecraft may give us some clues or guidance.
>> 
>> What would be neat, but it don't suppose we can expect Elecraft to do it, would be a board that would replace the planned internal 2m transverter, and would just act as a lower power transverter output from before the PA stages, on an SMA connector where the 2m antenna socket will be, with the main antenna BNC as a receive only port, (though that could be dangerous), perhaps a  low power TX/RX on the SMA would be best.
>> 
>> 73
>> 
>> David Anderson GM4JJJ
> 
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