On Mon, 23 Jan 2006 08:39:46 -0800, Tobin Fricke
wrote:

As a project to learn more about building radio receivers, I'd like to
build a WWV receiver (or maybe a receiver for the Canadian station CHU,
since it's nearby and the format sounds easier to decode). I'm looking
for suggestions for how to design such a radio, reading material, etc.

I was thinking it might be easier to design a fixed-frequency receiver
(rather than a tunable one) because I could just select the L and C in the
resonant circuit to give the right frequency. Or, since WWV is at such
"round number" frequencies, maybe I could somehow use a crystal
oscillator?

thank you,
Tobin

How about a simple one to three transistor regenative reciever. There
are several on the net.

Here's a few:

w1.859.telia.com/~u85920178/rx/regenrx.htm
http://www.techlib.com/electronics/regen.html
http://www.tricountyi.net/~randerse/regen.htm

Try Google for more.

Allison
no spam, no uce!

wrote:
How about a simple one to three transistor regenative reciever.

In principle that's a great idea, but the gotcha is that very near
WWV's 10MHz frequency there are a lot of powerhouse SW broadcasters.
Here on the East Coast in the evenings, there are at least 10 SW
broadcasters each of which are 10x more powerful all within +/- 100kHz
of 10MHz, several of them within 10kHz of 10MHz.

If I fire up my regenerative receiver (my trusty old Space Spanner that
my Dad bought for me when I was in 2nd grade!) WWV 10MHz reception does
not work at all in the evenings due to those broadcasters, my
particular regen just does not deal well with all those stations packed
so tight together. The adjacent broadcasters block up the receiver or
sometimes the regen locks onto them instead!

On 5 or 15 or 20 MHz, or on the west coast, the regenerative may welll
work better. (There are SW broadcasters near 5 and 15 but not nearly so
close and not nearly so packed.)

If the OP is looking for a build-it-yourself SW receiver for picking up
the powerhouse SW broadcasters, then a regen is a fine choice. In fact
my complaint is that my regen doesn't pick up WWV because of all those
other broadcasters outgunning it here :-).

Ten-Tec and others sell really nice regenerative receiver kits for SW.

Tim.

On 24 Jan 2006 07:58:14 -0800, "Tim Shoppa"
wrote:

wrote:
How about a simple one to three transistor regenative reciever.

In principle that's a great idea, but the gotcha is that very near
WWV's 10MHz frequency there are a lot of powerhouse SW broadcasters.
Here on the East Coast in the evenings, there are at least 10 SW
broadcasters each of which are 10x more powerful all within +/- 100kHz
of 10MHz, several of them within 10kHz of 10MHz.

If I fire up my regenerative receiver (my trusty old Space Spanner that
my Dad bought for me when I was in 2nd grade!) WWV 10MHz reception does
not work at all in the evenings due to those broadcasters, my
particular regen just does not deal well with all those stations packed
so tight together. The adjacent broadcasters block up the receiver or
sometimes the regen locks onto them instead!

On 5 or 15 or 20 MHz, or on the west coast, the regenerative may welll
work better. (There are SW broadcasters near 5 and 15 but not nearly so
close and not nearly so packed.)

If the OP is looking for a build-it-yourself SW receiver for picking up
the powerhouse SW broadcasters, then a regen is a fine choice. In fact
my complaint is that my regen doesn't pick up WWV because of all those
other broadcasters outgunning it here :-).

Ten-Tec and others sell really nice regenerative receiver kits for SW.

Tim.

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough
to overlaod and flatten out the selectivity.

At 5mhz I have no difficulty here is MA and at 10mhz it's still not a
problem. I've even heard WWVH from here when propagation was good.


Allison

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough to
overlaod and flatten out the selectivity.

Could you recommend a good introduction to the theory of the regenerative
receiver (and superregen)?

thanks,
Tobin

Tobin Fricke wrote:

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough
to overlaod and flatten out the selectivity.


Could you recommend a good introduction to the theory of the
regenerative receiver (and superregen)?

thanks,
Tobin


I'll recommend a little book that is readily available. "Secrets of
Homebuilt Regenerative Receivers" by C.F. "Rock" Rockey. Its a Lindsay
Publications book.
Rockey does a good job at simplifying the simple Basically the
concept of a regen is feeding the output back into the input for
reamplification. Theoretically its a somewhat infinite process in that
the reamplification continues repeating itself resulting in very high
gain at the particular frequency the set is tuned to and thats also
where the selectivity improvement comes from.
Its similar to oscillation in a tube.

The coupling issue mentioned by Allison is related in the sense that
heavy antenna loading will decrease the circuit Q and consequently
decrease its selectivity as the regenerative signal makes its round-trip
thru the circuit. That opens the window for strong stations that are
well off frequency to easily overload the circuit as a whole due to the
high magnitude of amplification. You'll see some circuits with direct
antenna connections to the tank circuit (bad)...some use a separate
antenna winding on the coil (better) some use capacitive coupling to
the tank...some use a combination of both.

Easy enough to build one for grins...might not be as stable as you would
want for your decoding project but would be a good, fun exercise just
the same.

GL,
Bill

On Tue, 24 Jan 2006 20:06:22 -0800, Tobin Fricke
wrote:

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough to
overlaod and flatten out the selectivity.

Could you recommend a good introduction to the theory of the regenerative
receiver (and superregen)?

thanks,
Tobin
You may want to consider this little regen receiver project. The board
for it is available from Far Circuits for around $5, or you could make
your own board.
http://www.electronics-tutorials.com...o-receiver.htm

Mike

On Tue, 24 Jan 2006 20:06:22 -0800, Tobin Fricke
wrote:

On Tue, 24 Jan 2006, wrote:

The trick with regens is to couple as loosely as possible. There is
enough gain in most regens that even a very loose coupling is enough to
overlaod and flatten out the selectivity.

Could you recommend a good introduction to the theory of the regenerative
receiver (and superregen)?

thanks,
Tobin

I Don't have any but I'd look on the net as there are gobs of circuits
with explanation. However the best explaied ones may be the older
tube designs.

Allison

Allison wrote:
[Regens]
The trick with regens is to couple as loosely as possible.

And, to the original poster (Tobin), don't take anything I wrote as
being bad about regeneratives being a great first receiver project.
They are a wonderful first receiver project. Just don't do it to
receive one particular station, do it instead to receive all the
interesting stuff going on.

Tim.

"Tim Shoppa" wrote in message
oups.com...
wrote:
How about a simple one to three transistor regenative reciever.

In principle that's a great idea, but the gotcha is that very near
WWV's 10MHz frequency there are a lot of powerhouse SW broadcasters.

Well, I suppose it depends on where OP is. Here in the middle, 10 MHz isn't
much of a problem but 15 is.

*HOWEVER*, 10 has one huge advantage -- there are very low cost uP crystals
for 10 MHz, so building even a simple reciever with a brick wall front end
isn't such a big deal, if the only frequency you care about is 10 MHz.
Personally, I'd go with a DC rather than a regen - a lot simpler and these
days, a simple SA612 will give you way more sensitivity than you can
possibly use on 10 MHz for a couple bucks. Well, with a crystal filter in
front maybe you will need a little amp, not so sure. But still quite a bit
simpler than a regen. Heck, if the local QRM isn't too strong, I bet a 10
MHz uP crystal, a 612 and an audio amp (like a 386 or so) is all you would
need.

A friend of mine did an article on a simple WWV reciever for QRP Homebrewer
recently, issue #5 I think. He was more interested in the frequency
standard than hearing the sounds, so his contribution was recognizing the
zero beat, but still an interesting article if you can find a copy.

...

On Tue, 24 Jan 2006 17:43:07 -0500, "xpyttl"
wrote:

"Tim Shoppa" wrote in message
roups.com...
wrote:
How about a simple one to three transistor regenative reciever.

In principle that's a great idea, but the gotcha is that very near
WWV's 10MHz frequency there are a lot of powerhouse SW broadcasters.

Well, I suppose it depends on where OP is. Here in the middle, 10 MHz isn't
much of a problem but 15 is.

*HOWEVER*, 10 has one huge advantage -- there are very low cost uP crystals
for 10 MHz, so building even a simple reciever with a brick wall front end
isn't such a big deal, if the only frequency you care about is 10 MHz.
Personally, I'd go with a DC rather than a regen - a lot simpler and these
days, a simple SA612 will give you way more sensitivity than you can
possibly use on 10 MHz for a couple bucks. Well, with a crystal filter in
front maybe you will need a little amp, not so sure. But still quite a bit
simpler than a regen. Heck, if the local QRM isn't too strong, I bet a 10
MHz uP crystal, a 612 and an audio amp (like a 386 or so) is all you would
need.

A friend of mine did an article on a simple WWV reciever for QRP Homebrewer
recently, issue #5 I think. He was more interested in the frequency
standard than hearing the sounds, so his contribution was recognizing the
zero beat, but still an interesting article if you can find a copy.


For wwv I consider DC the least useful. One approach I've also tried
is 9.6mhz crystal LO and use 455khz if can retuned to 400khz. that
works and uses fairly easy to get parts. That allows a diode
detector for zero beat against external sources and copy of the audio
without beats.

Allison