[Lowfer] Newbee Question

[Lyle Koehler]

>Do folks recommend a converter-direct-to-soundcard
>approach, i.e, Spectrum Lab, etc?

That's the lowest cost route. You have probably seen my article at
http://www.qsl.net/k0lr/SW-RX/sw-rx.htm  It takes some playing to get things
working right, but the results can be as good as you'll get with a much more
expensive setup.

>Would a converter in conjuction with a general coverage
>receiver as an IF be an equally good approach?
>If one goes this second route, what sort of frequency
>stability is required?

Because of the frequency stability issue, the answer is generally no. You
not only need excellent frequency stability in the receiver, but in the
converter as well. That's possible, but not particularly easy. My biased
opinion is that if you are going with the converter route, you might as well
try the downconverter approach instead. If you breadboard one of the
downconverter circuits at the above-mentioned web site and decide you don't
like it, all it takes is a different crystal to "convert" the downconverter
to an upconverter as shown at
http://www.computerpro.com/~lyle/proto/LFproto.htm

>I've been considering a TenTec Argo-V with TCXO
>for general ham transceiver use.  Would the Argo V's
>plus/minus three ppm be adequate stability?

Three ppm stability in an HF (or high MF) receiver used in conjunction with
an upconverter would be very marginal for the modes that most LowFERs are
now using. As you can see from the screen captures available on the Web, the
whole frequency window with Argo in 30-second dot mode is only about 6 Hz
wide. If you were using a ham transceiver at 2 MHz as the IF, 3 parts per
million would produce a 6-Hz error. Fortunately, the stability of a TCXO in
a ham transceiver is probably much better than 3 ppm over a period of hours
or even weeks. But you have to factor in the stability of the converter as
well. On the other hand, if you have a general-coverage receiver with 3 ppm
stability that tunes the LowFER band, the worst-case error at 185 kHz would
be less than 0.6 Hz.

Lyle, K0LR