[Icom] PRO 2 Display
Roy Sakabu
[email protected]
Tue, 18 Feb 2003 07:51:20 -0800
I have a question to throw out.
Of those who have experienced the display problem, how many turn off the
radio by switching the external power supply off?
I noticed that with my 746 that if I:
a). Turned the backlight to the lowest setting (thinking that I would
extend the life of the display)
and
b). Powered the unit off by turning the external power supply off and not
shutting the rig down first with its own power switch.
had the only experiences with a blank display on power up.
When I readjusted the backlight control, it came back on.
Since then I kept the backlight adjusted to full brightness and always turn
the rig off before shutting down the external power supply.
> -----Original Message-----
> From: Steve [SMTP:[email protected]]
> Sent: Monday, February 17, 2003 7:17 PM
> To: [email protected]
> 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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> Icom Users Net: Sundays, 1700Z, 14.315 MHz
> Icom FAQ: http://www.qsl.net/icom/
>
>
> ----
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> Icom Users Net: Sundays, 1700Z, 14.315 MHz
> Icom FAQ: http://www.qsl.net/icom/
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