[Icom] A couple of PRO 2 questions

Mon, 17 Feb 2003 22:23:22 -0500

My Pro is in the basement as well. All day long the temp is below 60.
I don't have the display problem, so perhaps it relates to the Pro2 display
being
different???
...Dave
----- Original Message -----
From: "Steve" <[email protected]>
To: <[email protected]>
Sent: Monday, February 17, 2003 10:17 PM
Subject: RE: [Icom] A couple of PRO 2 questions


> Adam,
>
> Thanks for the info.
>
> My shack is in my finished basement where the wintertime morning
> temperature is usually about 59 F.  I warm the area up thru the day but
> usually turn the rig on first thing in the morning.  The screen worked
> ok during the summer when the basement was typically warmer, and the
> problem only arose with the advent of cooler weather, which lends some
> credence to your idea.  Perhaps I'll try heating the shack area and then
> turning on the rig to see what the screen does.
>
> The AGC is set to fast, but I haven't done anything with the decay time
> so it's still set to factory default.  As a matter of fact I didn't even
> know it could be adjusted.  Obviously I have a lot to learn about this
> rig.
>
> Thanks for your advice, it is much appreciated!
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Adam Farson
> Sent: Monday, February 17, 2003 7:54 PM
> To: [email protected]
> Subject: RE: [Icom] A couple of PRO 2 questions
>
> Hi Steve,
>
> Regarding your first question: If the rig is stored at an ambient below
> 15 C
> (59 F) for a few days, the TFT display backlight may be sluggish in
> starting
> up. This may be due to condensation of the mercury vapour in the CCFL
> (cold-cathode fluorescent) backlight lamp. I assume that when you go
> away
> for a few days, you turn down the central heating; that would account
> for
> the sluggishness. I have observed this phenomenon on my 756Pro, which is
> in
> my lab/shop at 13 C - but not on my Pro II, which is in my shack at 18 ~
> 20
> C.
>
> On your second question: I have also observed this my station. I suspect
> that the apparent loss of sensitivity occurs when a very strong signal
> (or a
> noise spike) at the instant of switching from transmit to receive
> develops a
> large AGC voltage.  If this is the case, the duration of the apparent
> desense is a function of the AGC setting. If you select Fast AGC for QSK
> CW,
> and decrease the decay time via the menu, the symptoms may disappear.
>
> I went to the length of connecting to the Pro antenna socket a test
> fixture
> consisting of a directional coupler terminated in a dummy load. The
> reverse
> coupling port was connected to a signal generator. I adjusted the
> generator
> for an S1 reading at 14100 kHz, and then keyed the transmitter in the
> QSK CW
> mode. Using this test setup, I was unable to reproduce the desense -
> this
> led me to suspect that the cause was a strong signal or noise burst at
> the
> instant of the TX-to-RX transition. I do not think you have any reason
> for
> concern, unless the desense occurs on a regular basis.
>
> Hope this was helpful.
>
> Best 73,
> Adam, VA7OJ/AB4OJ
> North Vancouver, BC, Canada
> http://www.qsl.net/ab4oj/
> Icom FAQ site:
> http://www.qsl.net/icom/
>
>
>
>
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of Steve
> Sent: Monday, February 17, 2003 16:20
> To: [email protected]
> Subject: [Icom] A couple of PRO 2 questions
>
>
> I bought a new 756PROII about 6 months ago.  I notice two things about
> it that I'd appreciate some help with.
>
> First, it seems that if the unit has been off for a day or two (or
> longer) the screen doesn't light up immediately.  Last week, for
> instance, I was away for a few days.  When I returned and powered up the
> rig, the screen did not light up although the receiver began making
> audio in the typical ten seconds or so.  The screen came to life about a
> minute and a half after I hit the power switch.  After it's been on, if
> I turn the rig off and immediately turn it back on, the screen
> immediately lights up.  Anyone else seen behavior like this?
>
> Second question:  During the recent contest I noticed a few occasions
> when the 756PROII receiver seemed to desensitize for a few seconds after
> a transmission (CW, full break-in).  The audio output seemed to drop
> and/or the receiver sensitivity decreased.  It recovered on its own from
> this behavior within a few seconds.  This "desense" occurred perhaps a
> dozen times during the course of the weekend contest on 80 through 10
> meters.  Am I misadjusting something to cause this?  Or is something
> failing in the rig?  I use the 756PROII with a PW1 amplifier, Johnson KW
> Matchbox, open wire transmission line feeding a pair of dipoles.
>
> Thanks!
>
> Steve
> [email protected]
>
>
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