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Clarity of simple receivers	Reply
by N3QE on June 3, 2008	Mail this to a friend!
I am often amazed by the clarity, the impression of "hearing the world", that a simple receiver can provide. It can be a direct conversion or single conversion (with simple filters) homebrew or "old-fashioned" receiver, with simply lousy specs for intermod and filter skirt steepness and no AGC action at all, yet on a band anytime except a contest weekend it's like having my senses fully engaged. And then I hear a modern triple-conversion receiver with roofing filter and 12-pole crystal filter and DSP and while it's got really impressive intermod and other measurements, it's not nearly the same experience as having my "ears wide open". To my ears, filter ringing on such a set makes CW listening really really tiring and the AGC never seems to work right. Backing off from the "contest" tight bandwidths helps but it never sounds as clear as the simple single-conversion superhet from the 1960's. Is there a happy medium? The simple receiver with lousy spec does not deal well with contest weekends at all, mixing products from all the multi-kw stations up and down the east coast come out of the headphones all the time. Yet the super-duper triple-conversion DSP and 4 PLL loop receiver just isn't fun unless you really absolutely need to pull the signal out of all that surrounding QRM. Is it just the case that I want a "contest radio" for the tough stuff and my simple old radio for everything else?

RE: Clarity of simple receivers	Reply
by AA4PB on June 3, 2008	Mail this to a friend!
The easiest solution is two receivers. One for the contest weekends and the simple one for causual listening. Its probably not a simple matter of filter selection. The simple receiver likely has a VFO in lieu of a synthsizer thus no phase noise. Take a look at the Elecraft K2 for a good low-noise and clean receiver.

RE: Clarity of simple receivers	Reply
by KB1GMX on June 3, 2008	Mail this to a friend!
There are a lot of things that go into an answer to that. You not only comparing topology [direct conversion, single conversion superhet, triple conversion with DSP] but design quality and features. That muddies the answer greatly. Generally any of the mentioned topologies can be done to high or low standards. When any of those are taken are taken to the high standard of performance the result is good. However not all are created equal. There is no reason why a contest grade receiver has to sound bad and if anything it's desirable that it sounds very good as listening to it for 24 or 48 hours straight can be fatigue inducing and good sound is less so. A good single conversion radio can have performance in the standard of comparison level if executed well [K2 for example]. Often the things you refer to as negatives are a direct result if engineering and cost compromise or inattention to details like a decent speaker enclosure. I will agree that there are many radios that hear signals well but just grate on mhy nerves to listen to. Allison

RE: Clarity of simple receivers	Reply
by N0WVA on June 4, 2008	Mail this to a friend!
The answer wold be to homebrew your receiver to your own specs! Use stuff like DBM's and FET's to make a quiet yet strong receiver. Your right, some receivers have that "sweet" sound to them.

RE: Clarity of simple receivers	Reply
by W5ESE on June 10, 2008	Mail this to a friend!
> I am often amazed by the clarity, the impression > of "hearing the world", that a simple receiver > can provide. It can be a direct conversion or > single conversion (with simple filters) homebrew > or "old-fashioned" receiver, with simply lousy > specs for intermod and filter skirt steepness and > no AGC action at all, yet on a band anytime except > a contest weekend it's like having my senses fully > engaged. I agree with you. I have a simple direct conversion (Ten-Tec TKIT 1056) receiver for 40 meters, and I really like the "bright" sound that it has. I think others have encountered similar reception from the "Neophyte" receiver that was in QST in the late 80's. Most superhet receivers I listen to have a sort of "muddy" characteristic by comparison. > Is there a happy medium? Maybe so; I haven't tried it though. Bet you would find it worth trying the phasing type single signal direct conversion receivers that Rick Campbell has written about; the R2. http://www.arrl.org/tis/info/pdf/t9301032.pdf 73 Scott

RE: Clarity of simple receivers	Reply
by N3QE on June 11, 2008	Mail this to a friend!
> Bet you would find it worth trying the phasing > type single signal direct conversion receivers > that Rick Campbell has written about; the R2. > http://www.arrl.org/tis/info/pdf/t9301032.pdf Cool, I had been looking at the R2-related stuff in _Experimental Methods in RF design_. I had been turned off to direct conversion receivers by the HW-8. Not an awful radio I guess but lack of single signal selectivity was something I was not used to and it did not cope well at all on even typical evening 40M activity (the AM broadcasters just stomping all over the band). Sounds like it's time to build an R2! Tim.

RE: Clarity of simple receivers	Reply
by N2DTS on July 10, 2008	Mail this to a friend!
I built a few single conversion tube receivers that top anything I ever used as far as low distortion, and fidelity, very low noise, good filters. Think of a low distortion hi fidelity version of an old tube type table top AM receiver, with a good 455KHz filter.... No dsp, no noisy ic chips, no multi conversions, very low phaze noise. The receivers only cover 160 to 40 meters, but work real well there on AM. SSB and CW would require narrower filters which I dont have. This winter I may try building a CW rig using the basic receiver design with a product detector and a narrow filter. I tested a few tube type product detector circuits and found one that works real well. Most ham gear only has about 1 watt of audio output at 10% distortion, and limited freq response, into a little speaker, which explains a lot of it. Some of the older ten tec stuff sounds nice, the stuff before they went all IC chips. Brett N2DTS

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