Dave Holford wrote:
"Michael A. Terrell" wrote:
Dave Holford wrote:
I hear it fine with several different receivers provided I use either CW
or SSB. But! I CANNOT hear it on my IC-706; it does not seem to come
alive until somewhere between 200 and 300kHz.
Dave
Look at the design of the front end. If it is capacitor coupled, the
capacitive reactance is so high that it blocks anything below 200 KHz.
In this case you can add another cap in parallel to improve the lower
frequencies. Multiply the original by 100 or higher, and add it in
parallel to reduce the capacitive reactance, and the attenuation. I
built a broadband DC block for my bench at Microdyne that had five caps
in parallel. It was flat to less that a half dB from 50 KHz to 450 MHz,
and had a VSWR of less than 1.05 across the entire range. It was built
to maintain a 50 ohm impedance end to end.
If it has a transformer, the losses are too high at low frequencies. In
that case I would build a low pass filter and pre amp, and couple it to
the input of the mixer to see how it performs. You would have to shut it
off to use other bands, though.
Try using a HP312 series Frequency Selective Voltmeter for the
receiver.
Build a 60 KHz tuned loop and look at it with a scope. You can see
the modulation, because it is so slow. It is a CW signal with a 10 dB
gain reduction modulation with a maximum level change of twice per
second. (Normal and -10 dB) I built a three foot square copper loop with
an insulator where it was mounted on a cast aluminum electrical box, and
wound 20 turns of wire inside the 3/4" copper pipe after it was soldered
together. I used an op amp to give some gain,. and I could watch the
modulation. The big problem was a neighbor about a half mile away left a
TV set on 24/7 and the horizontal oscillator drifted after the station
went off, and the harmonics would drift right through 60 KHz. I wanted
to use it for a frequency standard, but I couldn't do it there. I will
try it again, some day, now that I have a couple miles of woods between
me and Colorado. I have enough gain to get around 12V P-P at the power
inserter. I used 75 ohm cable and "F" fittings because they were handy,
but I would use Mini Circuits MMICs and 50 Ohm cable if I built another
outdoor 60 KHz antenna.
--
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Take a look at this little cutie! ;-)
http://home.earthlink.net/~mike.terrell/photos.html
Michael A. Terrell
Central Florida
I have no problem receiving it on a number of different Ham and General
Coverage receivers using random wires or simple vertical whips. I also
hear it well with an active antenna. I have not noticed any real QRM
problems on 60kHz although there are some really strong noise sources at
other frequencies nearby.
Dave
45N 75W
They only signals I saw were WWVB, and that damned TV's harmonics
drifting through 60 KHz after the station went off the air. The guy was
only there a couple days a month, and left the TV on to make people
think he was home.
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We now return you to our normally scheduled programming.
Michael A. Terrell
Central Florida