Re: Designing OUR OWN rig!


Date: Wed May 17 1995 - 07:27:09 EDT

On Tue, 16 May 1995, PETER CALCANDY wrote:
> If the I-net group all participated in designing our own rig, it would
> look like a CAMEL!!!
> Regards,
Probably more like a CAM-EL-EPHANT.

The real question about mixers seems to be this: if not the 602, then
what? Improved 602 type chips? SBL mixers? Others? Which means would
be adequate to what sort of rig? All-CW. CW-SSB. All-mode. And where
in the rig. TX frequency mixing with VFO? RX front end? Detector?

I do not know if the 602 has a place in a modern receiver, but remember
that the 555 chip is even older and the 2N2222(A) older yet, and they
remain staples of QRP construction. Have even seen them in circuits in
EDN. Almost as if they were like old shoes--not up to wearing to church,
but mighty comfortable the rest of the time. Even the venerable 811 has
made a comeback in linears (due to cost) (but I have not thought of
designing one as a 5-watt QRP amplifier and winter shack warmer).

Actually, the ideal QRP rig may suffer from a lack of definition of the
ultimate use objectives. A backpack rig and a home-station rig may have
different requirements, and some of the requirements may differ in each
category, depending on the style of, say, field operation--tent, motel,
mountain top, open field, etc., as well as operating mode: contesting,
dxing, rag chewing, etc. Good design begins with a clear set of
objectives that can be translated into functional specifications that in
turn define the circuit design parameters. Why not both IF and AF DSP?
No reason at all, for some purposes; for others, lots of reasons to bypass
that technology in favor of other filtering means.

I suspect that behind each of the suggestions about what should be in the
ideal QRP rig is a thought in the mind of the person who offered the
suggestion of what he wanted it for and why. That is very important data
for making design decisions. I have doubts that there can be a single
ideal INET rig, but I suspect that there may be many ideal INET rigs,
each suited to certain purposes (and each slightly deficient in some way,
since our purposes/goals/objectives/uses for the rig will vary slgihtly
from person to person).


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