[Elecraft] KX3 Amp

[Geoffrey Mackenzie-Kennedy]

Igor,

Thank you for letting me know that you have managed to make some 3rd Order 
IMD measurements on your HLA 300 Plus amplifier, and for the data.

My apology for not replying sooner, I managed to fracture one of my leg 
bones (femur) on 30th March and have been in hospital recovering from the 
surgery.

Home now :-)

73,

Geoff
LX2AO



----- Original Message ----- 
From: "Igor Sokolov" <ua9cdc at gmail.com>
To: "Geoffrey Mackenzie-Kennedy" <lx2ao at pt.lu>
Cc: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Sent: Saturday, April 06, 2013 9:16 PM
Subject: Re: [Elecraft] KX3 Amp


> Geoff,
>
> Thank you for the idea on how one can measure relative IMD of the 
> amplifier,
> I have finally managed to do that with my HLA 300 Plus that I use with 
> KX3.
> K3 of my friend was used as the source. Measurements were done with QS1R 
> SDR receiver.
> K3 itself, with 2 tone engaged and running 100 W showed  3dr order IMD 
> at - 28db.
> HLA 300 Plus was driven by the same K3 (5W drive) and at the output of 
> around 180 W (20 m band) showed -25db of the 3rd order IMD. Anything above 
> 200 W makes IMD unacceptable (- 10db at 300W). The situation is a bit 
> better on lower bands (160 and 80m ) where one can go up to almost 250 W.
> Anyway it seems that with 5 W drive and output power of below 200W, HLA 
> 300 Plus can be used on all the bands quite successfully.
> I have also modified the amp to work from PTT signal only, and disabled RF 
> VOX in it.
> RF band sensing remained intact.
>
> 73, Igor UA9CDC