[Elecraft] Strange behavior when tuning around with SUB receiverLINKED

[James Sarte]

Hi Matt,

The "zipper" or "motorboat noise" occurs when tuning around 4.9-5.5 MHz or
4900-5500 KHz.  It is most noticeable when the sub receiver is turned on,
the sub volume is up, and tuning steps are set to fine.  The noise ONLY
occurs when I turn a VFO knob or filter knob.  If I do not touch any knob,
the noise does not occur.  It does not matter if VFO A or VFO B knob is
used, or whether or not they are linked.

So think of it like this: when I am in that band area, if I continuously
turn a VFO knob, I will hear the motorboat noise until I stop turning the
knob.

If I pass that particular frequency area, the noise disappears completely.  

Also, I am using beta firmware 2.82.  When I am tuning around with the sub
receiver's VFO linked to the main, if I encounter a band edge, I hear a
relay click and then the difference between both frequency counters can be
anywhere from 500-900 KHz apart.  In order to get them to match, I have to
press A/B then A > B to duplicate the frequency.

73,
James KC2UEE



-----Original Message-----
From: Matt Zilmer [mailto:mzilmer at verizon.net] 
Sent: Sunday, February 22, 2009 5:54 PM
To: James Sarte
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Strange behavior when tuning around with SUB
receiverLINKED

James,

What rev of firmware are you using?  I went through test on all of
them I could with the subreceiver, which I didn't install until 2.72
was current.  I can't duplicate your results with 2.82.  It may not be
a firmware-related issue (or issues).

In the first problem statement, it sounds like you have the VFO's
linked.  Are you also in DIVRSTY or not?

As I understand it, the spectrum covered is carved up into band
sections, each allowing the VCO control voltage to traverse a good
part of its control range.  Very few (if any?) of these breaks is
within a ham band.  The behavior you described at 5997 could be tied
to the down-tune break at that freq.  The up-tune break is 5 KHz or so
higher.  You might want to see if you can repeat this tuning up as
well.  I can't duplicate this problem here with 2.82.  If there is a
real bug here in the FW rev you're using, it *ought* to affect tuning
in both directions.

For your second problem statement, the following may apply.  There is
a chirp radar between 5184 and 5212 KHz (approx).  The chirp goes
through the passband pretty quickly, maybe within 150-200 mS and the
rep rate is a little under one second.  It's a wideband signal, and
you may be hearing it as a zipper-like noise.  You didn't say whether
or not you heard it as a repeated or continuous signal, so I can't be
sure this is what you're describing.

73,
matt zilmer, W6NIA