Einar Persson wrote:
>
>No I have not measured it. Someone on this list said that the TS2000 has
>a lousy TX with IMD just a few figures better than 20db below pep.
>I think the figures came from a British test of the radio.
>
>Maybe Peter or Ian can help with the correct figures?
>
Peter's away from his e-mail for the weekend, so I guess it falls to me.
At 100W PEP output, 3rd orders at HF were -26 to -31dB below PEP, ie -20
to -25dB below either tone. At 50MHz -21/-15dB, at 144Mhz -24(-18)dB
and at 432 (51W PEP) -22/-16dB. 5th orders were 10-16dB lower; no higher
orders were measured, so we have no idea how far across the bands this
thing spreads.
As quoted earlier, the reviewer said "SSB two-tone distortion levels
were rather high but improved significantly at lower powers" but data
were not quoted. He has always been known for choosing rather mild words
for his criticisms, so you do have to learn to read his code for "bloody
appalling".
I did some measurements on my IC-746 a few months ago, and sure enough
that was "rather high" as well - just as reported by the same reviewer.
What really surprised me was that the IMD at the *input* to the PA was
just as bad... it creeps in somewhere in the TX chain at very low
levels, possibly due to some kind of design fault in the diode
switching. Haven't got to the bottom of that yet, but I will, some day.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|