[PCR-1000] PCR-1000 Front end overload

Tue Sep 7 07:30:38 EDT 2004

Thanks RJ,

I will investigate further.

73,

Martin

-----Original Message-----
From:	R. J. Grasser [SMTP:rgrasser at frontiernet.net]
Sent:	Monday, September 06, 2004 8:37 PM
To:	martin at classaxe.com; Discussion of PCR-1000 by Icom
Subject:	Re: [PCR-1000] PCR-1000 Front end overload

Hi Martin,

First off.... dont call me "MR" or "SIR"  I havent been a USAF officer since
1964 :-)  RJ is just fine ;-)

I really cannot help you as the overall system is dependent on its
individual components and their interactions.  few people realise this
factor.

I find the MJF-1045C to work just fine with my H-800 active antenna, and
ST-2 broadband dipole array.

While it is not supposed to "function" below 1.8 Khz it does work down to
100 Khz with limited effect.  Anything that works down there is  a + :-)

Regards, RJ
----- Original Message -----
From: "Martin Francis" <martin at classaxe.com>
To: "'Discussion of PCR-1000 by Icom'" <pcr-1000 at mailman.qth.net>
Sent: Monday, September 06, 2004 7:09 PM
Subject: RE: [PCR-1000] PCR-1000 Front end overload

> Hi there Mr Grasser,
>
> I looked up the presector at MFJ's web site.   It seems that it only goes
> down to 1.8MHz - great for Hams, less so for NDB / MF DXers.
>
> I found another product by MFJ that looked interesting:
> http://www.mfjenterprises.com/products.php?prodid=MFJ-956
>
> If you click on the 'Download the MFJ-956 Manual' link you see a very
> simple circuit diagram - switchable inductor in series with 365pF tuning
> capacitor.
>
> 1/(2 * PI * sqrt(L*C))
>
> The inductors for the bottom couple of bands are 2.5mH and 33uH.
Assuming
> a usable tuning range of 40-365pH:
>
> 2.5mH gives 166-503KHz.
> 330uH gives 458-1385KHz
>
> If you wanted to rearrange the formula with a known capacitance of say
1nF,
> for a frequency of 1110KHz... you'd need a bigger brain than I have.   I'm
> hopeless at these things.
>
> Now my question is, if this thing is wired to shunt out the unwanted
signal
> (i.e. the shunt goes between antenna and earth), and you add extra
'stages'
> to remove other frequencies, or does the whole thing just turn into one
> almighty mathematical mess?
>
>
> Any ideas?   Or do I have to build it and try it?
>
> ?
>
> Martin Francis <><
> =============================================================
>  NDBList:   Mapmaster, Country Co-ordinator and NDBRNA Editor
>  Location:  Richmond Hill, ON, CANADA / FN03GV
>  Antenna:   Twin K9AY 140' loops on 300 feet of coax
>  Receiver:  ICOM PCR1000 (2.8KHz filter) + DSP-599ZX
>  Software:  NDBWebLog, WWSU, Argo, Goldwave, SkySweep, NDBRNA
>  Beacons:   581 received since May 7, 2003
>
>  Web Site:  http://www.classaxe.com/dx
>  NDB Log:   http://www.classaxe.com/dx/ndb/log
>  NDB Maps:  http://www.classaxe.com/dx/ndb/maps
>  NDBRNA:    http://www.classaxe.com/dx/ndb/ndbrna
>  NDBRE:     http://www.classaxe.com/dx/ndb/ndbre
> =============================================================
>
>
>
>
> -----Original Message-----
> From: R. J. Grasser [SMTP:rgrasser at frontiernet.net]
> Sent: Monday, September 06, 2004 5:09 PM
> To: DB Nicholson; Discussion of PCR-1000 by Icom
> Subject: Re: [PCR-1000] PCR-1000 Front end overload
>
> First off ground your radio at the "in ground" side of your water pipe.
> Your house wiring, or the power meter may not be anything more than a
> "floating ground".
>
> If you have the money, buy an MFJ-1045C active preselector ($67.00 on the
> web), as it has a very sharp cutoff notch filter.
>
> We also have a 50 KW station about 7 miles from us, but using the 1045C in
> conjunction with my H-800 active antenna (10 Khz to 50 Mhz) from LF
> Engineering, and my ST-2 broadband vertical array (30 Mhz to 1.3 Ghz), I
> can
> totally eliminate the offending AM station, and its images/harmonics.
>
> RJ (rgrasser at frontiernet.net)
>
> Rochester, NY
> ----- Original Message -----
> From: "DB Nicholson" <d_nicholson at bellsouth.net>
> To: <pcr-1000 at mailman.qth.net>
> Sent: Monday, September 06, 2004 12:09 PM
> Subject: [PCR-1000] PCR-1000 Front end overload
>
>
> I live less than 3 air miles from a 50kw AM station (WBT - 1110).  Front
> end
> overload makes AM band reception useless.  I am using a longwire abt 30'
> above ground.  Radio is grounded using the house ground at power meter.
> Someone once suggested using an RC filter to shunt 1110 to ground, but I'm
> not sure what components to use, etc.  Any help would be appreciated!
> TIA,
> Dave
> Charlotte, NC
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