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List:       elecraft
Subject:    Re: [Elecraft] P3 Sprogs
From:       George Danner <gdanner12 () gmail ! com>
Date:       2022-01-31 20:44:27
Message-ID: CA+N9gcxoUaEAj3iLg=1w8EJtsVx=GGq90Hhb4o76d2X-ADkBcA () mail ! gmail ! com
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BNC cables do have issues all of their own. First a manual connector seems
difficult for some to terminate properly (especially the shield).
Connectors have 2 sizes of center pins (50 & 75 ohm). Using a large
connector and then a smaller conductor will cause an intermittent at the
female center.

As a broadcaster who converted from video on PL259s to BNCs, we became very
aware of these issues. To the point that 75 ohm BNC jumpers in the shop had
green tape or shrink tubing and 50 ohm had red. More than 99% of our
plant's cables were 75 ohm! We only stocked 75 ohm connectors at the studio
and 50 ohm connectors at the transmitter.
There were several attempts to have a single compatible connector. Not sure
that was actually accomplished!

I had a similar issue shortly after I installed my P3. I just used a solder
pick to tighten the K3 & P3 BNCs female center leaves. Fixed my issue with
a 2010 P3 kit. Not sure which of the 4 connectors was the culprit - the
cable is Elecraft, K3 & P3 are Elecraft.

Memory from long ago seems to remember the 75 ohm pin was the smallest
diameter; so using a 50 ohm connector could expand the female and then
using a 75 ohm connection could become intermittent.

73 George AI4VZ

On Mon, Jan 31, 2022 at 3:00 PM Fred Jensen <k6dgwnv@gmail.com> wrote:

> I had a similar problem when I first got my P3.  The symptom(s) centered
> around the noise drifting upward.  Hand on top would send it back down
> to the baseline.  One of the Elecraft techs [who I know well] sent me a
> new jumper on the condition that I cut the old one into 5 cm pieces so
> it didn't show up at a swap meet.  The new one fixed the issues.
>
> The P3 is really a tuneable receiver that covers most of the HF
> spectrum.  We just leave it tuned to the 8 MHz 1st IF.  If the
> cable/connectors are not really shielded well, it will pick up ambient
> noise.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> Victor Rosenthal 4X6GP wrote on 1/31/2022 1:06 AM:
> > Trevor,
> >
> > Try another coax jumper between the K3 and P3. I have heard of this
> > problem being caused by poor connection of the shield braid (or
> > low-quality braid) in the jumper.
> >
> > 73,
> > Victor, 4X6GP
> > Rehovot, Israel
> > CWops #5
> > Formerly K2VCO
> > https://www.qsl.net/k2vco/
> >
> > On 31/01/2022 10:09, MØTDZ wrote:
> >> I am sure I have seen some threads on this before so please accept
> >> apologies If i am going over something twice.
> >>
> >> Having moved to an area with a  much lower noise level I note loads
> >> of sprogs / spurious signals following me around on the P3
> >> panadapter.  Is there a common cause of these (im presuming they are
> >> generated by the K3S) and anything I should/could be doing to get rid
> >> of them?
> >>
> >> Trevor MW0TDZ / M0DX
>
>
>
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