For a decent Spectrum Analyzer, 9kHz to 1.5 GHz with tracking generator,
check out the Rigol DSA 815-TG. It is available for under $1500 and
free shipping for Amazon Prime members. Not only is it an aide to the
station equipment but it is an excellent piece of test equipment. As
one reviewer stated, "it won't do what the Agilent Spectrum Analyzer
costing some 10X as much will do but for the price, it is an excellent
value".
73 Bob, K4TAX
K3S s/n 10,163
On 9/1/2015 10:18 AM, Rick Stealey wrote:
I have been playing with a Flex 6300 here in my shack recently. I consider it
a great piece of test equipment for analyzing signals in the shack as well as
on the air. It does everything and more, as a spectrum analyzer, that my old
HP141 analog setup did, except it doesn't have a tracking generator.
My measurements are not completed and I am still experimenting, but here is
what I've done so far. Phase noise, cw transmitted bandwidth, and 2 tone IMD
tests. My two rigs are a K3/100 and an FT100D (how good, and how bad can you
get!)
Using a Flex 6300 as a spectrum analyzer, I fed a greatly attenuated signal
into it, keeping the level just under 0 dbm, and assuming it is not generating
imd of its own, but I haven't quantified that yet.
Phase noise tests - I was interested in seeing if it could display the RELATIVE
benefit of the new synthesizer on my K3, looking at phase noise. Here are
PRELIMINARY RELATIVE results, without numbers, in order of phase noise level at
2 khz separation:An 8640B signal generator (known to have low phase noise)The
K3 with original synthesizerThe FT100 After I install the new synthesizer I
hope to be able to compare it to the original one.
I verified the FFT spectrum analyzer (Flex 6300) can give an instant view of
transmitted bandwith of the cw signal sending fast dots. MUCH easier and better
than the old analog HP spectrum analyzer which had to sweep extremely slowly
across the band with a narrow filter. With this setup you hold the key closed,
and hit the control-print screen buttons on the keyboard and you have a
beautiful picture ! Ain't technology great?
2-tone IMD measurements -The two tone test of the K3 showed something
interesting, since it has both 10 watt and a 100 watt PAs installed. Starting
with low power and cranking up the power control, you notice, of course, that
the ten watt PA has worse IMD just before the big PA kicks in, in the 11-12
watt range. Then it is very clean (approximately -40 db for third order) at
its best, and ok in the 30 watt range (where it would be set to run my 8877
amp) but then gets quite ugly above 65 watts. And I mean in the -20 db range
at 100 watts. IF it was overloading the spectrum analyzer these tests would be
invalid, so I need to verify that. As I said these tests are preliminary. I
need a few more hours.
In my humble opinion, running at full power, 100 watts barefoot, my K3 would be
transmitting an unacceptably sloppy signal. Keeping it in the 65 watt range or
under, or driving an amp would be better, provided your amp is clean. My 8877
amp is VERY clean. I don't know about a solid state amp. Some of the ugliest
signals I have seen on the bands with the Flex panadapter in very limited
observations have come from Expert 1500 watt amps (2 examples). The very best
was an Anan 100 with a Ten Tec 1500 watt tube amp. The waterfall was a brick
wall - NOTHING whatsoever outside the 3 khz bandwidth.
Rick K2XT
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