[HBR] Function Versus Form?

[hbr@mailman.qth.net]

In a message dated 12/16/03 10:08:35 PM Eastern Standard Time, 
mcintosh@triad.rr.com writes:


> 1)  6V6/6AQ5 final audio.  Are these really used that often?  I tend to use
> headphones almost exclusively, so I'm tempted to leave a beefier,
> speaker-ready amplifier as an outboard project.  Thoughts?


Purely a matter of personal preference - I've built receivers both ways. The 
receiver of mine pictured on the website drives headphones only (6K6 output 
stage in a circuit shamelessly stolen from the ARC-5 receivers). Outboard 
speaker driver amp not only saves space and reduces heat but can be used with 
multiple receiver projects. With audio iron getting rarer all the time, it can be 
worth doing.

A trick I've used with such setups is to use the output trans from an ARC-5 
receiver to get ~600 ohms output at "comfortable headphone level". Then an LC 
audio filter (see QST for December 1971 IIRC) cleans up the audio. 'Phones or a 
speaker driver follow the filter.

> 
> 2)  Keeping it all in one box?  One problem I have is that I just don't have
> a suitable box to house the full receiver.  I have two that are way too big
> and a few that are smaller.  I'm tempted to keep the lower IF and headphone
> audio in one box, the higher IF, VFO, and input in another box, and an
> umph-y audio with speaker in another.  Although this would consume metal,
> the modules should have improved isolation, right?

Yes and no - running low-level signals between chassis can be a bit of a 
bother to avoid ground loops and such. How big a box do you need?


> 
> 3)  AM detector.  How may of you use yours?  I have no AM gear, and have
> felt more of a pull to stick with CW than to branch out.  Maybe an HBR-8 or
> HBR-11 style would be better.
> 

One of the advantages of homebrewing-from-scratch is putting in exactly what 
*you* want. My receivers have long been CW-only, to the point that there's no 
S meter, no AGC, and no provision for wide selectivity. Never miss 'em, 
either.

73 de Jim, N2EY


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