I have used an Autek QF-1A Filter with my Argonaut 509 for many years
now. i keep saying that i am going to modify it and insert it into the
chain ahead of the audio amp. there is a plug on the back of the Argo for
an external filter. I currently have 2 QF-1A filters, but they are out
of production and becoming scarce like the origional Argo Filters.
I used a home brew one for years. You can buy an audio filter module
kit from EMTech, W6EMT for about $20. It is pretty much the same as the
CWF-2 that MFJ used to make. Most people that I have heard froom say that
it does nicely. The QF-1A runs around $50-60 if you can find them.
A real top notch filter. Does SSB and other tricks as well. You also
might want to investigate the Switched Capacitor Filters that are
sold by Oak Hills Research. I understand that they work quite well.
If they are as good as the SCF in the QRP +, they would be perfect for
the Argonaut. there is nothing like a good audio filter to improve the
results with your Argonaut. Except maybe a BIgger Antenna. :-)
72 es
QRP DX TU (C) 1986 G.Danny Gingell, K3TKS@.abs.net
Maryland Milliwatt QRP Reference Library, (301)572-6789
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