[Elecraft] [KX3] JT65 and JT9 possible TX issues

[Harry Yingst via Elecraft]

Just curious how is the New and improved Stock Heatsink from Elecraft?

I just got my KX3 and have not had time to try it out in the digital modes



      From: Neil Zampella <neilz at techie.com>
 To: elecraft at mailman.qth.net 
 Sent: Saturday, May 9, 2015 10:48 AM
 Subject: Re: [Elecraft] [KX3] JT65 and JT9 possible TX issues
   
FWIW ... I did the temperature compensation routine and added an 
aftermarket heatsink to my KX3.  I can transmit JT65 at 10 w without 
hitting the HiTemp issue.  I decided to add some additional cooling, so 
I yanked an old 12v CPU cooler out of one of the old desktop computer 
cases I have laying around, soldered on a few powerpole connectors, and 
have that sitting on top of the KX3 to provide extra cooling.  No 
HiTemp problems on JT9 with that running at all.

At 5 to 10 watts, I've hit all continents except for Asia, and that's 
more an issue with my antenna than with the radio, as I can QSO with 
Australia at 5 w on JT65 if I hear them.    This is from Southwest PA 
near Pittsburgh.

Neil
KN3ILZ


On 05/07/15 11:27 pm, Jim Brown wrote:
> On Thu,5/7/2015 7:15 PM, Gary Hawkins wrote:
>> In an ideal world, I'd pair the KX3 with KXPA100 under low drive but 
>> if the KX3 is not the right radio for JT65/JT9 then perhaps it would 
>> be better to buy another JT65/JT9 out-the-box ready rig for the home 
>> shack and keep the KX3 for portable ops (around 80 SOTA activations 
>> so far and counting).
>
> The ONLY shortcoming of the KX3 for JT65/JT9 is heating during the 
> long TX cycle, which in practice limits its output to about 3W, and 
> you want an aftermarket heat sink. Use that 3W to drive a KXPA100 to 
> about 60W, and you've got an excellent radio. You would need to move 
> up to a K3 to get better. and 60W is a LOT on JT65 and JT9. More power 
> than that is used only on 160M, 6M, and weak signal modes like 
> moonbounce. On HF, most JT65/JT9 is in the range of 5-30W.
>
> Temperature stability is only an issue on 6M and above.
>
> 73, Jim K9YC
>
>
>
>
>

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