[Elecraft] How sensitive is sensitive?

Mon Dec 30 14:07:03 2002

Barry I was at the stage you are now at a week ago (3075 is now complete)
and I have an IFR1200S, I needed to add external attenuator pads to get the
actual sensitivity reading on my K2.  When the calculations were done it
came out to less than .02uV sensitivity.  This measurement was made after
the entire radio, all bands including 160 and transmitter was up and running
and completely tuned.....I've never had such a hot receiver.  I'm in the
process of doing selectivity tests and IM tests on both Tx and Rx and should
have some results in a day or so.  By the Way when I looked at the specrtrum
analyzer for the transmitted signal all harmonics were greater than 80dB on
my completed radio. This exceeds any commercial HF rig I've ever owned in
the past 39 years of Amateur Radio.

Gregg R. Lengling, W9DHI
PSYCHOLOGY:  The science of inventing words for things that do not exist.

----- Original Message -----
From: "Barry Cooper" <[email protected]>
To: <[email protected]>
Sent: Monday, December 30, 2002 12:54 PM
Subject: [Elecraft] How sensitive is sensitive?

Hi Everybody,

I have just completed the Part II alignment and was able to listen on 40m to
my K2 for the first time! It works - great!. I was able to hear both CW and
SSB signals clearly but not particularly loudly through a set of 8 ohm
Sennheisser audio headphones. So far so good, and the K2 met all the Part II
alignment criteria within spec. to the extent that I could measure. Not
having a calibrated signal generator to inject a -100dBm signal at 7+ MHz
etc. I used a 12 inch test lead clipped to the aerial socket and peaked L1
and L4 off air (on air?). I found a birdie at 7001.50 which I used to tweak
L34 for peak signal, minimum noise as suggested in the instructions. My
questions are these: a) can I retune something (what?) to shift the 7001.50
birdie down outside the band?  (I don't need to do this now but would like
to do so before finalising the tuning) and b) How do I know whether I am
within spec for receive sensitivity? A side by side aural comparison with my
Kenwood TS870S using the same antenna seemed to show the K2 down in
perceived sensitivity but I didn't build the TS870S and the K2 isn't
finished yet! Any of you experts out there give me a steer on this??

Happy New Year to all - especially Lisa for getting my missing parts to me
in time for the Christmas holiday.

73,
Barry Cooper
G4RKO

K2 # 2906

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