KX1 RX Sensitivity on 20M vs 30M, 40M

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KX1 RX Sensitivity on 20M vs 30M, 40M

Reed-11
Michael wrote:
Have others noticed less RX sensitivity on the KX1 on
20M as compared to 40M and 30M?Yes, I have noticed that too.  Went back & did the whole aliment thing, but no change.  Receives good, just have to crank up the volume more.Reed  W4JZ
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RE: KX1 RX Sensitivity on 20M vs 30M, 40M

Howard W. Ashcraft
Yes.  I also get less change (as compared to 30m and 40m) when changing RF gain.  I have also noticed (as predicted by Elecraft) that the KX1 is sensitive to your choice of headphones.

-----Original Message-----
From: Michael Babineau [mailto:[hidden email]]
Sent: Thursday, August 19, 2004 8:51 AM
To: [hidden email]
Subject: [Elecraft] KX1 RX Sensitivity on 20M vs 30M, 40M


Have others noticed less RX sensitivity on the KX1 on
20M as compared to 40M and 30M?

I recall that this was noted in the QRP Quarterly review
of the KX1 a little while back and I have also noticed this
on my own rig, so I am guessing that this is normal.

Sensitivity is still sufficient on 20M but requires
cranking the AF Gain a little higher on 20M
than the other bands to get a similar signal
volume.

Michael VE3WMB

P.S. This came to my attention again last night as I had
to realign the Rig after finally getting around to installing
the 30M module. BTW For such a little board the KXB30
was a real pain in the you-know-where to install!

P.P.S I also put the Elecraft supplied sticker over the opening
on the KXPD1 and it now looks much better !


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RE: KX1 RX Sensitivity on 20M vs 30M, 40M

Eberhart, Russell
In reply to this post by Reed-11
I have also noticed somewhat reduced sensitivity on 20M, but sort of
expected that.  

Into a 50 ohm dummy load, and into 1.0-1.1 SWR antennas, I get about
3.3-3.5 watts out on 40M, 4 watts on 30M, and 3.0 watts on 20M.  Have
re-aligned...get the same.  Is this typical?

I didn't experience any frustration with 30M module.  It all seemed to
go together just fine for me.

I've had dozens of QSOs with my KX1, and only have one unusual behavior
(of the KX1...we won't go into mine) to report.  Sometimes I get noise
that is there when the LEDs are on, and goes away when the LEDs time
out.  Has anyone else experienced that?  It does not happen all the
time.  Furthermore, it seems to be more likely to happen when I've been
operating for a period of time, say at least 30-60 minutes.

Anyway, I'm very pleased with the KX1.  Just put together a little
portable battery pack that uses two 4-AA cell packs and one 2-AA cell
pack that I populate with NiMH batteries.  It gives me about 12 volts
for portable operation.

Russ Eberhart, N9IV
KX1 #742
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Re: RE: KX1 RX Sensitivity on 20M vs 30M, 40M

Leigh L. Klotz Jr WA5ZNU
Administrator
I think the manual says to squeze one of the output toroids until you
get less output on 20m than on 40m, as a sign that the filter is
properly adjusted for harmonic reduction.

When I was building my KX1, I brought it to a PAARA club meeting where
Wayne was speaking, and he looked at my KX1 toroids which were evenly
distributed, and said I needed to follow those instructions in the TX
portion of the manual.

On Sat, 21 Aug 2004 10:11am, Eberhart, Russell wrote:
> Into a 50 ohm dummy load, and into 1.0-1.1 SWR antennas, I get about
> 3.3-3.5 watts out on 40M, 4 watts on 30M, and 3.0 watts on 20M.  Have
> re-aligned...get the same.  Is this typical?

73,
WA5ZNU Leigh
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RE: KX1 RX Sensitivity on 20M vs 30M, 40M

Reed-11
In reply to this post by Reed-11
Eberhart, I get the same output as yours.  I did the transmit toroid
thing several times & got no more than 3 watts out on 20, 3.3 to 3.5 on
40, & 4 watts on 30.  This was done using a 13.6 volt supply.  Using  a
12 volt supply I get 3 watts out on 20 & 40 meters.

I only notice the noise when the S meter is being used.

73s,
Reed  W4JZ

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RE: KX1 RX Sensitivity on 20M vs 30M, 40M

Michael Babineau
In reply to this post by Reed-11
Reed <[hidden email]> wrote :

 >Eberhart, I get the same output as yours.  I did the transmit toroid
 >thing several times & got no more than 3 watts out on 20, 3.3 to 3.5 on
 >40, & 4 watts on 30.  This was done using a 13.6 volt supply.  Using  a
 >12 volt supply I get 3 watts out on 20 & 40 meters.

 >I only notice the noise when the S meter is being used.

Ditto for me. I get about same output as Reed and I have noticed
Buzzing (sounds like uProcessor whine) if I switch the display mode
to S meter .. which I never use fortunately. Other than that the
rig works fine for me.

The reality is that on the receiving end the difference between 3W and
4W
isn't noticeable so I guess we shouldn't be too concerned.

BTW, I worked MM0MWW / P at the Hoxa Head Lighthouse in the Orkneys
with the KX1 yesterday on 20M. I was operating portable using a vertical
24ft wire (suspended from a 24ft fishing pole) and 5 X 16ft radials on
the
ground.

Michael VE3WMB


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KX1 RX Sensitivity on 20M vs 30M, 40M

Klaus Koppendorfer
In reply to this post by Reed-11
i did a lot of measurements due to low sensitivity on 20meter with
trackinggenerator and spectrumanalyser the real max peak of the 20meter
bandpass filter is at lower frequency (abt 13 MHz) if you align the
filter for "max" gain on 14 Mhz the peak ist abt 6db lower as on 13MHz i
did some changes at filter caps.... but there is a strong influence with
the other two filters (40, 30 meter) maybee elecraft has there a new
redesign with new filter values - just see with analyser the filter
curves..

73
OE6KYG
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