Using the SB-301 on CW

[Kenneth G. Gordon]

On 1 Feb 2007 at 9:23, Allen Jones wrote:

> The 1000 Hz note you get when you center a CW station
> using the Heath CW filter is much too high in
> frequency for me.  I prefer something lower, 700-750
> Hz which seems to be the norm for most of the stuff
> built today.  Anyone aware of a mod to change the peak
> frequency?  I assume it would require shifting the
> BFO.

Allen:

I also find that 1Khz pitch to be MUCH too high, and the same thing 
holds true for the Heathkit SB/HW transceivers with the 400 Hz filter.

Assuming that the desired signal is somewhat centered in the 400 Hz 
bandwidth of the filter, you SHOULD be able to adjust the BFO to give 
you a much lower pitch.

Remember that parallel capacitors lowers a crystal's frequency, while 
series capacitance raises it, but you may not be able to move it 250 Hz.

I say it is worth the effort.

I also use an external audio filter, with a center-frequency of about 750 
Hz, with bandwidths of 180, 110, and 85 Hz. It is the CWF-3, made 
originally by Autek, later by MFJ, and now by Vectronix. I bought 
several at a hamfest for no more than $3.00 each. They run on a 9 Volt 
battery.

Vectronix still sells those, and some fancier ones.

Ken W7EKB

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