EMRFD Message Archive 3938

Message Date From Subject
3938 2010-01-01 18:34:43 Tim Listening to receivers again: HW-16 this time
40M tonight is nice with almost zero QRN and a good amount of activity.

I worked ZP6CW, and then have been listening to ZP6CW working a long line of callers on 7003. Using a number of different receivers, the rapid flutter on ZP6CW is always apparent, but some of the receivers just do a better job making it easily listenable. I had warmed up the HW-16 last night and used it on SKN, and now I'm listening to the ZP6CW activity using it. When I first turned on the HW-16 last night it had taken my ears a little while to adjust to it, after having spent a long time using my other rigs, largely in CW contests, with 8-pole crystal filters, or my mini-R2 with some different audio filtering. But tonight I'm impressed with the clarity the HW-16 has when it picks up on ZP6CW through the rapid flutter compared to the other rigs. Certainly the lack of AGC on the HW-16 helps. But there's also something magical about the two-pole crystal lattice filter.

Gotta do more listening :-). I think the HW-16 hits a very sweet spot for non-contest 80M and 40M work. The audio has a certain quality to it too, I'm not an audiophile who gushes over tube amps, but there's something very transparent about the audio channel. (The fact that I'm listening on my favorite 14" speaker helps the mellowness, I'm sure! Can't stand tiny speakers.)

Maybe I should build a nice simple tube CW receiver, with two-pole crystal lattice filter, that'd perform on 30M and 20M too. Maybe a 7360 or 6AR8 for the mixer. Plug in coil sets would be fun.

Tim.
3939 2010-01-03 12:24:25 KK7B Re: Listening to receivers again: HW-16 this time
Hi Tim,

I like the sound of a 2 crystal half-lattice filter as well. I uploaded descriptions in the files secti
3940 2010-01-03 15:20:26 Tim Re: Listening to receivers again: HW-16 this time
I go through different cycles... contesting CW using an 8-pole crystal filter, then casual CW operation with my simpler receivers. Every time I move from the fancy-pants filters to a simpler receiver, I am astonished at how much easier they are to listen to for extended periods.

It takes me a little while to switch gears back and forth between the two modes, maybe some hours of operation before I stop thinking "this sounds funny".

I am very impressed with the gain distributions in the compact and simple superhet you uploaded. Wow, talk about "compact"!!! Impressive cordwood construction there.

Many of the same ideas that I attribute to "QRP" thinking, seem to go back at least to the 1960's, e.g. the 1965 ARRL Handbook "Misers Dream", the Simple-X Super, etc. The only thing I really don't get about many of those otherwise simple designs, is why they insist on putting a "Q-multiplier" in front of the mixer, or adding regeneration in the detector. I appreciate several kinds of regenerative receivers but don't always grok why they are mixed in with CW superhets. Maybe the regeneration in the detector was because they weren't using crystal filters and it was a way of giving a tighter bandwidth without a bunch of IF transformers/stages.

Tim N3QE

3941 2010-01-03 15:50:21 k5nwa Re: Listening to receivers again: HW-16 this time
At 05:20 PM 1/3/2010, you wrote:
>
>
>I go through different cycles... contesting CW using an 8-pole
>crystal filter, then casual CW operation with my simpler receivers.
>Every time I move from the fancy-pants filters to a simpler
>receiver, I am astonished at how much easier they are to listen to
>for extended periods.
>
>It takes me a little while to switch gears back and forth between
>the two modes, maybe some hours of operation before I stop thinking
>"this sounds funny".
>
>I am very impressed with the gain distributions in the compact and
>simple superhet you uploaded. Wow, talk about "compact"!!!
>Impressive cordwood construction there.
>
>Many of the same ideas that I attribute to "QRP" thinking, seem to
>go back at least to the 1960's, e.g. the 1965 ARRL Handbook "Misers
>Dream", the Simple-X Super, etc. The only thing I really don't get
>about many of those otherwise simple designs, is why they insist on
>putting a "Q-multiplier" in front of the mixer, or adding
>regeneration in the detector. I appreciate several kinds of
>regenerative receivers but don't always grok why they are mixed in
>with CW superhets. Maybe the regeneration in the detector was
>because they weren't using crystal filters and it was a way of
>giving a tighter bandwidth without a bunch of IF transformers/stages.
>
>Tim N3QE

Regeneration will increase the gain of the circuit vastly so for
simple radios it eliminates having extra added stages to get enough
gain to be a useful receiver. The extra selectivity doesn't hurt either.


Cecil
k5nwa
www.softrockradio.org www.qrpradio.com
< http://parts.softrockradio.org/ >

Never take life seriously. Nobody gets out alive anyway.
3942 2010-01-03 17:04:29 Tim Re: Listening to receivers again: HW-16 this time
3943 2010-01-03 17:19:38 KK7B Re: Listening to receivers again: HW-16 this time
Hi Tim and Cecil,

When done well, regeneration can be a useful technique. The more modern term is "Active Filter," and modern receivers often have those.

Regeneration and Q-multipliers are often associated with low-cost and simple gear, and that often involves compromises. But even the Collins 75S3C used a Q-multiplier to implement the notch function at the 455 kHz IF. The 455 kHz Q-multipliers used in Drake and Hammarlund receivers, and sold in the thousands as accessories by Heathkit worked very well in both peak and notch mode.

Byr
3944 2010-01-04 08:46:53 ai9e_qrp Direct Conversion Receiver Webinar
There is an on-demand Webinar from Analog Devices available, covering direct-conversion receiver technology:
http://www.techonline.com/learning/webinar/222100099


FYI

73 Dave NM0S
3945 2010-01-04 08:52:51 aa7hq@comcast.net Re: Listening to receivers again: HW-16 this time
i read in some of this stuff that the HW-16 is an excellent receiver, because it has "MAGIC". balderdash!
i read in some of this stuff that posting an engineering estimate of the behavior of certain devices
earns you a lecture on popular usage trumps real engineering. piffle!
what i see is a painful trend, and certainly many of you know better, towards

DUMBING IT DOWN!


ed, aa7hq




----- Original Message -----
3946 2010-01-04 10:26:46 Tim Re: Listening to receivers again: HW-16 this time
3951 2010-01-06 09:40:10 KK7B Re: Listening to receivers again: HW-16 this time
Hi Ed,

Nice to hear from you--your comments are delightfully frank and hit the mark as usual. It is much more pleasant to be admonished using terms like balderdash and piffle than the harsh rhetoric of the modern era.

There is profound science behind the different sound of receivers A and B, and if we dig in to understand the science we can make some progress, and then design and build better receivers. That takes math and physics--more than even most engineers are comfortable using these days.

Back to the bench--applying the scientific method and pondering Boltzmann's constant. Speaking of "dumbing it down," that's my reaction to the way engineers treat noise...One man's dumbed down circuit is an another man's useful simplification.

Again, thanks for the encouragement to THINK!

Best Regards,

Rick KK7B