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
----- Original Message -----
From: "Geoffrey Mackenzie-Kennedy" <[email protected]>
To: "Igor Sokolov" <[email protected]>
Cc: "Elecraft Discussion List" <[email protected]>
Sent: Tuesday, March 26, 2013 8:59 PM
Subject: Re: [Elecraft] KX3 Amp
Hello Igor,
If you want to measure (with useful accuracy) the level of the IMD
products generated by your KX3 and HLA 300 Plus, all that you would need
in addition to your TS590 is a Two Tone (AF) Generator, an AF Spectrum
Analyser and your computer. If you Google Tcube you will find a program
called Tcube, which can be downloaded at no cost. This program will
provide you with a Two Tone Generator and an AF Spectrum Analyzer. The
frequency range covered by the generators and the Spectrum Analyser is 0
to 10 kHz. I have found this program to be useful when running 3 or 4
tone tests, two of the tones from a "hardware" generator.
73,
Geoff
LX2AO
On March 25, 2013 at 7:14 PM, Igor Sokolov wrote:
I do not have equipment to accurately measure IMD of my combo of KX3 and
HLA 300 Plus. Having said that I drive HLA 300 with 5 w from KX3. It gives
me 200 + watt on all the bands. Listening to the radiated signal using
TS590 and different antenna reveals that the occupied bandwidth is within
the same boundaries which I have determined by transmitting 100 W from my
K3. Therefore I assumed that IMD of the above mentioned combo is no worth
then 30db.
73, Igor UA9CDC
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