[PCR-1000] PCR-1000 Front end overload

Tue Sep 7 15:05:23 EDT 2004

Hi Martin,

According to MFJ the 956 is limited to 1.5 to 30 Mhz, and they dont suggest
you "mess with it".

My antenna "math" is circa the early 60's and mostly forgotten due to old
age, and lack of practise ;-)

Took the ICOM down on the MF/LF band for the first time today.  Nothing but
spurs, harmonics, images, and general noise (except for the LORAN-C on 100
Khz).

In "my days", I never ventured over 80 Meters, so I really dont know what
might be down there.

I did note in one of my frequency tables there is a EU Ham band at 135.7 to
137.8 Khz.  Is it used here as well?  What modes are used, and when can I
expect to hear "anything"?

Did you get Bonito 4.5 with your receiver?   If not, I can xmit you the
files on email (also the ID codes).

Bonito has an excellent CW decoder (automatic) if you reset the defaults to
CF=800Hz, BW=200Hz, and set the tune increment to 1Hz with an IF of 3 Khz.

Bonito falls apart when it comes to hi-res NOAA images from the satellites
since it is a standard FAX mode part of the software.

If your into "imaging" the satellites, download the free version of WXTOIMG
from the Kiwiland website.  The widely used WXSAT freeware is a really "poor
cousin" to WXTOIMG !!

My APC UPS battery just bit the dust this morning when the "replace battery"
alarm came on for the first time.  Battery lasted 5 years.  Its going to
cost me $145.00 to replace it.

Speaking of which.  I know why Im not seeing 60 Hz images.  The BP-1000
generates a trapezoid on its output instead of a stepped sinewave like most
UPS's.  Seems the receiver cant see it.  Thats a nice little "perk" :-)

Whats your QTH btw?

Regards, RJ (rgrasser at frontiernet.net)

----- 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
> ______________________________________________________________
> PCR-1000 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/pcr-1000
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:PCR-1000 at mailman.qth.net
>
>
>
>
> ______________________________________________________________
> PCR-1000 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/pcr-1000
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:PCR-1000 at mailman.qth.net
> ______________________________________________________________
> PCR-1000 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/pcr-1000
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:PCR-1000 at mailman.qth.net
>
>