I'm kind of shooting in the dark without a service manual so I appreciate
you taking the time to offer suggestions Ty.
I crossed over at the 3 & 4 MHz points as you suggested and didn't notice
any difference. Maybe I'm still learning the nuances of this radio but it
just sounds dead on 80. I don't recall if it was like this when I first
picked it up. I'm having a real battle with power line noise so I haven't
spent much time on the low bands. Last evening I came across a weak GM3
calling cq. In the flat position he was just strong enough that I could
copy his call but when I switched over to the tuned, there was no way I was
going to hear him.
Your point about too much gain is well taken. I've found especially on
10 meters, that the receiver is hot. That's great for working weak stuff
but I too use the RF Gain or ATT when the band is really crowed with signals
which is usually in the morning to Europe. For those of you who have not
seen it, there is a good article on "How to Get the Most from Attenuators
and Preamps" in the November/December issue of the National Contest Journal.
It was written by Gary K9AY.
73
Ken K4ZW
----- Original Message -----
From: "Tyler Stewart" <k3mm@erols.com>
To: "Ken Claerbout" <K4ZW@Staffnet.com>; <yaesu@contesting.com>
Sent: Monday, January 01, 2001 10:50 PM
Subject: Re: [Yaesu] 1000MP - Decreased Signal Strength on Low Bands
> Well, hang on a minute.
>
> You SHOULD see a decrease in sensitivity on frequencies below 7 mhz in
TUNED
> mode. TUNED mode on the low frequencies kicks in a higher dynamic
> range/lower sensitivity preamp. Usually this is good choice, but not for
> low sensitivity RX antennas such as bevs, EWE's, etc., unless you run a
lot
> of preamplification before it hits the radio RX ANT IN jack.
>
> If you still think there is a problem on 80, try passing through the BPF
> crossover points at 3 and 4 mhz and see if the sensitivity changes as you
> pass through 80. If it drops at all, you've probably got damage in your
RX
> BPF for 3 to 4 mhz (I've had a coil short out there as well).
>
> The key thing to remember on any radio is that you should be hearing
> atmospheric static in the background over the normal hiss of the RX with
no
> antenna. If you dont, you arent going to hear the weakest signals. Do
> whatever you need to do to fix the problem.
>
> The flip side is that you shouldnt run more gain than you need, especially
> on crowded bands as this just invites RX overload. I've found that using
> the RF Gain control on the MP seems to be the best choice over other
options
> such as the attenuator and the IPO button.
>
>
> 73, Ty K3MM
>
> ----- Original Message -----
> From: "Ken Claerbout" <K4ZW@Staffnet.com>
> To: "Tyler Stewart" <k3mm@erols.com>; <yaesu@contesting.com>
> Sent: Monday, January 01, 2001 9:53 PM
> Subject: Re: [Yaesu] 1000MP - Decreased Signal Strength on Low Bands
>
>
> >
> > Thanks for the suggestions Ty. Using my 80 meter 4 square, I have a
> local
> > line noise of S6 when in the tuned position and S9 in the flat setting.
> > Switching the 4 square between the Antenna A jack and RX Ant In, I did
not
> > see any change. The same thing happens on 40 & 160 although it seems to
> be
> > most pronounced on the low end of 80 meters. Any other suggestions?
> >
> > 73
> > Ken K4ZW
> >
> > ----- Original Message -----
> > From: "Tyler Stewart" <k3mm@erols.com>
> > To: "Ken Claerbout" <K4ZW@Staffnet.com>; <yaesu@contesting.com>
> > Sent: Monday, January 01, 2001 6:31 PM
> > Subject: Re: [Yaesu] 1000MP - Decreased Signal Strength on Low Bands
> >
> >
> > > Try using the RX In jack and see if everything sounds normal. If so,
it
> > > sounds like a bad high pass filter section. The RX ANT In jack
bypasses
> > > this board. This is on a separate board before the main RX RF board
and
> I
> > > believe is only IN when in TUNED mode and is not in line when using a
RX
> > > antenna. If it still occurs, I almost guarantee, it's the 80 meter BPF
> > > section in the receiver. Note that the BPF's are always in no matter
> what
> > > preamp you are using.
> > >
> > > I've had problems with this and some of the bandpass filter sections
in
> > the
> > > receiver. What I've found every time is that the little molded coils
> they
> > > are using short out some turns. It's not something you can find
> visually.
> > > You have to start lifting leads and measuring or just shotgun
> > replacement.
> > >
> > > I just dug out my tech manual for the MP and have noted that L3503 on
> the
> > > HPF-UNIT is the first coil to ground in the 80 M HPF and has failed
once
> > on
> > > both of my MPs! It's a 1.8uH rf choke and it's Yaesu part # L1790049.
> > >
> > > Note that this is a very easy board to work on. It's located near the
> > right
> > > rear top of the radio behind the AFC board and just in front of the
A/B
> > > relay board in front of the SO239 jacks. It's mounted on a couple of
> > > plastic, snap-in standoffs and the board should be marked with the
L3503
> > > designator.
> > >
> > > SHould be an easy fix if you can handle basic electronic repair!
> > >
> > > 73, Ty K3MM
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Ken Claerbout" <K4ZW@Staffnet.com>
> > > To: <yaesu@contesting.com>
> > > Sent: Monday, January 01, 2001 2:28 AM
> > > Subject: [Yaesu] 1000MP - Decreased Signal Strength on Low Bands
> > >
> > >
> > > >
> > > > I noticed during the CQWW CW contest this past November, that
signals
> on
> > > 80
> > > > meters seemed unusually weak. With all the solar activity going on
> that
> > > > weekend, I wrote it off to poor conditions. Thinking about this a
bit
> > > > further, I recall that over the past month or two, 80 meters has
> sounded
> > > > unusually quiet. I decided to do a side by side comparison with my
> > > Kenwood
> > > > 940 and promptly noticed that signals on 80, including power line
> noise,
> > > > were 20 dB weaker on my 1000MP. No wonder I was having a hard time
> > > chasing
> > > > the weak DX stations! Taking a closer look, I also see this
happening
> > on
> > > 40
> > > > & 160 although it was not apparent until now.
> > > > I swapped the two rigs just to eliminate any potential problems
> with
> > > > cables, filters, or something specific to that operating position
and
> > the
> > > > problem followed the radio (1000MP).
> > > > The radio is set for a tuned front end and when I switched it to
> > flat,
> > > > using the broad front end amp, signals came back up on all three
> bands.
> > > > This would seem to indicate that there is a problem with the low
band
> > > tuned
> > > > RF amp. However, the diagram in the manual labels the range for
this
> > amp
> > > as
> > > > 1.9 - 7 Mhz. Is this front end section actually in use on 160
meters
> in
> > > the
> > > > 1.8 - 1.9 Mhz range and also on 40 meters between 7 Mhz and 7.3 Mhz
> or
> > is
> > > > the wide band amp used in these frequency ranges? If it's the
latter,
> > > then
> > > > that kind of kills my theory about the low band amp. Is there
> anything
> > > else
> > > > setting wise etc. that I should be checking?
> > > > In the event I have to get this repaired, I'd appreciate
> suggestions
> > > as
> > > > to where I should have this done.
> > > >
> > > > 73
> > > > Ken - K4ZW
> > > >
> > > >
> > > >
> > > >
> > > > --
> > > > FAQ on WWW: http://www.contesting.com/FAQ/yaesu
> > > > Submissions: yaesu@contesting.com
> > > > Administrative requests: yaesu-REQUEST@contesting.com
> > > > Problems: owner-yaesu@contesting.com
> > > >
> > > >
> > >
> > >
> >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/yaesu
> > Submissions: yaesu@contesting.com
> > Administrative requests: yaesu-REQUEST@contesting.com
> > Problems: owner-yaesu@contesting.com
> >
>
>
--
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