[PCR-1000] PCR1000 s/n 6153

Tue, 09 Apr 2002 17:16:32 -0400

Sensitivity is fine and well, but what are we really looking at here? Signal-to-noise ratio. The radio will receive best with a certain level of signal and the lowest possible noise. If you overload the front end, you're hosed. First, the filtering is a very good idea - for instance, on my 800MHz antenna setup, I use a ~12dB gain fiberglass omni, brought down with Belden 9913 coax, through a Minicircuits bandpass filter to pass roughly 810-890 @ 0db attenuation, then through a low-noise Advanced Receiver Research preamplifier to increase the signal as much as possible, into an eight-way Telewave power divider. Everything uses high-quality coax (9913 for the antenna and short runs of a super-high-quality version of RG-58 (can't remember the number right now, but it's the same thing as 9913 is to RG-8X, this cable is to RG-58) and connectors (Ns and BNCs, always). This drops my noise level as low as possible (filtering), then adds amplification, some of which is lost in the powe!
r division stage.

Another tool which is quite handy is a selectable attenuator. Usually found in 1db increment varities (cheaper versions), or 0.1 or 0.01db possibly digital varieties (lab-grade test equipment), these devices let you quickly find where your receiver reacts best. Then, you can build/buy an attenuator for approximately this value.

Priorities:
Good antenna, GOOD COAX, and good connectors
Grounding
Filtering
Amplification/attenuation

Keep in mind that you are using a broadbanded receiver. It's not going to be as good as an R-7000 (not that expensive), and it's certainly not going to compare to a radio designed for a single band. There are some limitations (physics) that are unavoidable...

Terry

On Tue, 9 Apr 2002 16:25:00 -0400 Matt Loretitsch <[email protected]> wrote:

Just like a radio overloading in an urban area yes....

And yes a sensitive receiver is normally a good thing.  You could try a high
pass, low pass, or band pass filter to help eliminate the intermod.  Is
there a tower somewhere near you?  If you use the G5RV as a low band (sub
30mhz) antenna then add a low pass filter inline and that might really help
out.  Paging towers and such cause trouble as does the national weather
service tower at 162.550 mhz right by my house.... I can hear it everywhere
in a cheaper radio... The PCR-1000 doesn't seem to have that trouble
thankfully.  When I tune to that frequency it pushes the meter to FULL
scale.

http://www.mfjenterprises.com/products.php?prodid=MFJ-704

40 mhz low pass and 1500 watt claimed power handling

http://www.vectronics.com/vectronics/products.php?prodid=LP-30

Same thing practically... Same parent company anyway :)

http://homepage.tinet.ie/~ei9gq/lpf.html

Roll your OWN!  (I might just try this one myself for low band reception)

Maybe someone else has better ideas!  I'd try to identify WHAT frequency(s)
is/are causing so much intermod and then filter it out somehow.

-Matt

-----Original Message-----
From: A10382 [mailto:[email protected]] 
Sent: Tuesday, April 09, 2002 4:20 PM
To: [email protected]
Subject: Re: [PCR-1000] PCR1000 s/n 6153

The PCR-1000 does seem to overload it's front end easily.  I would think
that means that it is a very sensitive receiver (this is supposed to be
good?).  You could try turning on the Attenuator (ATT Button on the
'Mode/Vol' Panel).  I believe this provides about 20db of attenuation.

If you're still receiving a lot of intermod, then a smaller discone antenna
and/or a tuner may help.  However, another antenna may reduce the weaker
signals.....

73s

----- Original Message -----
From: "George Worthington" <[email protected]>
To: <[email protected]>
Sent: Tuesday, April 09, 2002 2:13 PM
Subject: Re: [PCR-1000] PCR1000 s/n 6153

> I have to admit that hooking a large outside antenna (G5RV) to my 
> PCR-1000 results in "intermod" showing on just about all frequencies 
> selected on Talk PCR.  The only way to clear it is to go to a smaller 
> discone or use my antenna tuner.  Is this normal for the radio?
>
> George
> N7BUI
>
>
>
>
>
>
> On Tue, 9 Apr 2002, Paulo wrote:
>
> > Nico,
> > for first,  try to put a good antenna connected to
> > your PCR!
> >
> > I�ll never work my PCR with the whip, only for a
> > brief test when I buy mine !
> >
> > This antenna can be a 1/4 wave ground plane for
> > VHF and a long wire for the HF bands.
> > Or like you are a HAM, use your antenna system
> > as usual.
> >
> > Don�t forget to disconnect all when not in use or
> > when the weather goes bad ! (thunderstorms)
> > The SMD�s inside this little box are very sensitive.
> >
> > I hope your PCR comes to "life" for your pleasure !
> >
> >  See you,
> > Paul (PY2LMS)
> > Sao Paulo, Brazil.
> >
> >
> > ----- Original Message -----
> > From: "Nico de Jong" <[email protected]>
> > To: <[email protected]>
> > Sent: Tuesday, April 09, 2002 4:02 AM
> > Subject: [PCR-1000] PCR1000 s/n 6153
> >
> >
> > Hi again
> >
> > I have now tried everything I could think of, including Steves Eprom 
> > contents (s/n 5216), Marcos realignment program and  statistical 
> > values
from
> > PCRBUR.
> > Some time ago I also tried Pres' values, but all to not much avail. 
> > I can now hear some non-repeater based transmissions on 144 MHz, the 
> > 49m band is superb, the rest of shortware (6-20 MHz) is acceptable 
> > and I can hear carriers on the air band (around 120 MHz). BUT, 
> > nothing above 200 MHz. I'm still using the supplied whip.
> >
> > Would it be appropriate to send it to SouthAfrica ? I dont think I 
> > want
to
> > bother with ICOM.
> >
> > What is your opinion / suggestion ?
> >
> > Nico (OZ1BMC)
> >
> > _______________________________________________
> > PCR-1000 mailing list
> > [email protected] 
> > http://mailman.qth.net/mailman/listinfo/pcr-1000
> >
> > _______________________________________________
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> >
>
> _______________________________________________
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