[RESEND] Re: [Coco] COCO 3 for LowFER transmitter?

[KnudsenMJ at aol.com]

In a message dated 12/12/03 11:31:46 AM Eastern Standard Time, 
bathory at maltedmedia.com writes:

> Correct in that a pure CW signal is better than an amplitude modulated
>  carrier is for 
>  reception. The narrow bandwidth requirements of a receiver for slow on off 
> CW carrier will reflect in lower noise power density within the bandpass.

True.  FWIW, MCW (modulated CW, that is, AM modulated with Morse code beeps) 
is used on the Beacon Band just above the 150-190 LOWFER band.

One mistake made by the aircraft beacon stations is using a very high-pitched 
tone, maybe 1000 Hz or more.  It requires too much receiver BW to copy.  If 
you use MCW, try a lower pitch, 400 Hz or less.  That will allow the receiver 
to tighten up its bandwidth against the horrendous light-dimmer noise on this 
band.

> Also at that frequency and that low a power I would
>  recommend 
>  a tuned loop antenna for transmitting. It will meet the requirements. The
>  efficiency can be made quite high. Much higher than any loaded vertical. 

I've not heard much about transmitting with loops much smaller than an 
equivalent dipole antenna.   Loops are definitely the best for receiving at these 
low freqs, whit much less noise pickup.   A small loop may indeed be as good a 
transmitting antenna as anything you could fit in your yard, and ISTR that the 
Lowfer rules limit your total antenna length to 20 feet or the like -- not 
that you'd expect to abide by that, but since a quarter wavelength is almost a 
mile, you'll not get much more out of a long wire in your backyard.

I wonder if Lowfer experimenters have tried Coherent CW, where each dot and 
dash is synchronized to the WWV timebase of NBS/NIST.  --Mike K.