RadioBanter - Stable Regen Receiver--Does it Exist??

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Stable Regen Receiver--Does it Exist??

I have built a few dozen regen receivers and they all seem to work well
enough on AM signals--some extremely well--but kind of fall apart when
it comes to STABLE reception of CW and SSB.

Has anyone ever built a solid state regen that does well with CW and
SSB? If so I would love to know how you did it (I'd even share my some
of my massive collection of radio parts with you)...before I go off and
build another dozen regens.

I have a box full of prototypes affectionately dubbed my radio reject
graveyard (or dead radio pile)...I just don't want to be up to my neck
in more prototypes before I finally get a good one.

Seriously thinking of skipping it and building a simple DC or superhet.

Bruce Kizerian kk7zz
www.elmerdude.com

) writes:
I have built a few dozen regen receivers and they all seem to work well
enough on AM signals--some extremely well--but kind of fall apart when
it comes to STABLE reception of CW and SSB.

Has anyone ever built a solid state regen that does well with CW and
SSB? If so I would love to know how you did it (I'd even share my some
of my massive collection of radio parts with you)...before I go off and
build another dozen regens.

I have a box full of prototypes affectionately dubbed my radio reject
graveyard (or dead radio pile)...I just don't want to be up to my neck
in more prototypes before I finally get a good one.

Seriously thinking of skipping it and building a simple DC or superhet.

I don't know. But for much of their life, they have been treated as
simple receivers. First in the twenties or so, when things were expensive
so it was as minimal as possible. In more recent decades, because they
were seen as a beginner item, an alternative to a complicated superhet.

Simple is bound to mean tradeoffs. Realistically they are oscillators,
yet how often is the care put into them that someone puts into a
free running oscillator? A thick piece of wire for the coil, built
really strong to avoid microphonics, with temperature compensating
capacitors and voltage regulation, just like in a vfo. Add a stage
of isolation between the antenna and the detector, just as you'd
isolate a vfo from it's load. Bypass it will, instead of saving
money by having only one capacitor. Use a good sturdy variable capacitor,
rather than the one you got out of the AM portable.

If you built an oscillator like most regens are built, would you
expect much stability?

One of the neat things about solid state is that the cost of
extra active components is virtually nill, in terms of actual price
and in terms of space. You're not blowing the food budget to
buy that single tube so you can try out the receiver you built.

Look at Charles Kitchins work. Unlike when solid state
first came along, he went back to the basics, read up on the
early articles about regeneration, and then proceeded to try
to make them better in solid state form. So you see that extra
stage to isolate the detector from the antenna. You see a voltage
regulator. And it will still be cheaper than that single tube
receiver in the old days.

I've never built a regen, but the things he puts in his
receivers were things I had been thinking about if I'd
wanted to build a good regen.

Michael VE2BVW

"John Ferrell" wrote in message
...
May be I should not post before the second cup of coffee in the
morning, but it seems to me that stable regeneration nets out to a
Q-Multiplier. Don't let me discourage your activities, you would not
be the first to find a new life for an old method.

Personally, I find myself thinking about Parametric amplifiers a good
bit these days...

On 23 Aug 2005 19:30:56 -0700, wrote:

I have built a few dozen regen receivers and they all seem to work well
enough on AM signals--some extremely well--but kind of fall apart when
it comes to STABLE reception of CW and SSB.

Has anyone ever built a solid state regen that does well with CW and
SSB? If so I would love to know how you did it (I'd even share my some
of my massive collection of radio parts with you)...before I go off and
build another dozen regens.

I have a box full of prototypes affectionately dubbed my radio reject
graveyard (or dead radio pile)...I just don't want to be up to my neck
in more prototypes before I finally get a good one.

Seriously thinking of skipping it and building a simple DC or superhet.

Bruce Kizerian kk7zz
www.elmerdude.com

I have an older - but in reasonably decent condition - Radio Shack Regen
receiver which does like 590 KC - 30 MHz - operates on 4 "C" batteries and
has a jack for external power - bought it at an estate sale. I was able to
scrounge up a manual for it too. I've used it a few times, but Regens are
not my idea of a good time. Have thought of putting it out to the public for
those who like em - but not sure yet if I'll do that. Maybe I'll give it
another shot - let it try to earn it's keep. It is small enough, I thought
about using it with a QRP transmitter and have a nice portable set up. Maybe
I'll try to tune it up per the manual. I hadn't tried that yet - the radio
became a back burner project since I bought it. Tuning "may" make a world of
difference! Who knows when the thing was last checked or if it was even done
right to start with. The thing is kinda neat looking, so would hate to get
rid of it. But, if I"m not going to use it, no sense letting it collect
dust.

clf

There's a good article in Jan/Feb 2004 QEX by WD5HOH for A Cascade
Regenerative Receiver with two regen stages. The article covers what must
be done to achieve stability with references to other regen articles.

--

73
Hank WD5JFR
wrote in message
oups.com...
I have built a few dozen regen receivers and they all seem to work well
enough on AM signals--some extremely well--but kind of fall apart when
it comes to STABLE reception of CW and SSB.

Has anyone ever built a solid state regen that does well with CW and
SSB? If so I would love to know how you did it (I'd even share my some
of my massive collection of radio parts with you)...before I go off and
build another dozen regens.

I have a box full of prototypes affectionately dubbed my radio reject
graveyard (or dead radio pile)...I just don't want to be up to my neck
in more prototypes before I finally get a good one.

Seriously thinking of skipping it and building a simple DC or superhet.

Bruce Kizerian kk7zz
www.elmerdude.com

I assume you are talking about temperature induced drift, as opposed as
frequency lability due to hand effect, changes in regen setting etc.

I have experienced such stability over time that SSB pitch would stay
dead on for days (run on and off) in the shortwave range with the radio
tuned on a volmet station half a continent away. In this instance, I
was running a 1-tuber with direct heated filament, battery powered, and
cap-throttle regen control, but the lessons apply in general.

The main tricks in my book are quite simple:
- keep oscillator power as close to zero as humanly possible
- keep voltages stable
- select LARGE components and hookup wires
- ensure ventilation!

In a word, make sure the oscillator basically runs at ambient
temperature.

If you were referring to frequency lability caused by other factors, I
have good news in the hand effect department, and mixed news in the
regen control area.

Hand effect can be more or less got rid of by proper shielding or
decoupling. You can find an interesting discussion he
http://tinyurl.com/dr936 .

In a word: keep your body away from ANY capacitance related to the
oscillating tank circuit - and that mainly refers to the ANTENNA, not
the variable capacitor or the coil. If there is a sizeable
antenna-case capacitance, then a change in body-case capacitance
affects antenna and inevitably the tank circuit too.

So the oscillating tank circuit must be properly decoupled (usually by
RF amp/buffer stage ahead of the regen detector)
OR
it must be well enclosed + the antenna coax fed
.... or both.

I would like to experiment with cap-decoupling by putting a
slitted-shield around the tuning coil, and putting a separate antenna
coil next to it, but never got around to doing so. Even theoretically,
the idea of such a trick gives me a headache.

In the regen control department, the mixed news is that capacitive
throttling is considered the "best performing" way to go, but can't
avoid to affect the tuned frequency.

[ In theory you could, of course, what with a small co-shafted VC that
removes capacitance from the main LC as the throttle cap adds it, but
it must be a pretty complicated law, and I don't know of anyone who
tried it :) ]

You can instead turn to the gain-control way, DC-controlling one of the
following:
- second grid voltage in a pentode
- plate voltage in a triode
- base voltage in a transistor
or some such like.

All of the above minimize frequency change especially in tube designs
(where varicap effects are basically nonexistent), but can suffer from
annoying hysteresis, in my experience more than cap throttle. Not sure
where the "high performance" advantage of cap throttle is though...

Another trick I wish I had tried is changing a *stabilized* voltage, as
opposed to using a simple throttle pot. That could be done with a
variable regulator IC and might remediate the hysteresis.

Another trick is to use a couple of effects working in opposite
directions, such as a resistive throttle that adds gain but shunts more
RF to ground, such as in the Charles Kitchin "Beginner's Radio".

See www2.arrl.org/tis/info/HTML/regen/
with many derivatives linked in this article of mine:
http://www.geocities.com/filippo_cat...sert-ratt.html .

I think the same trick may be in use in the MFJ-8100 regen, but I can't
tell what's trimmer and what's main control pot.
(hand drawn schematic may be he
www.diagram.com.ua/list/mogik.shtml
sorry Martin!).

So, there's hope.

Way back when... I listened to the SSB gangs on 40M with my Knight Kit Space
Spanner, but then, I'm in my own world.
73, Steve, K9DCI

"SpamHog" wrote in message
oups.com...
I assume you are talking about temperature induced drift, as opposed as
frequency lability due to hand effect, changes in regen setting etc.

I have experienced such stability over time that SSB pitch would stay
dead on for days (run on and off) in the shortwave range with the radio
tuned on a volmet station half a continent away. In this instance, I
was running a 1-tuber with direct heated filament, battery powered, and
cap-throttle regen control, but the lessons apply in general.

The main tricks in my book are quite simple:
- keep oscillator power as close to zero as humanly possible
- keep voltages stable
- select LARGE components and hookup wires
- ensure ventilation!

In a word, make sure the oscillator basically runs at ambient
temperature.

If you were referring to frequency lability caused by other factors, I
have good news in the hand effect department, and mixed news in the
regen control area.

Hand effect can be more or less got rid of by proper shielding or
decoupling. You can find an interesting discussion he
http://tinyurl.com/dr936 .

In a word: keep your body away from ANY capacitance related to the
oscillating tank circuit - and that mainly refers to the ANTENNA, not
the variable capacitor or the coil. If there is a sizeable
antenna-case capacitance, then a change in body-case capacitance
affects antenna and inevitably the tank circuit too.

So the oscillating tank circuit must be properly decoupled (usually by
RF amp/buffer stage ahead of the regen detector)
OR
it must be well enclosed + the antenna coax fed
... or both.

I would like to experiment with cap-decoupling by putting a
slitted-shield around the tuning coil, and putting a separate antenna
coil next to it, but never got around to doing so. Even theoretically,
the idea of such a trick gives me a headache.

In the regen control department, the mixed news is that capacitive
throttling is considered the "best performing" way to go, but can't
avoid to affect the tuned frequency.

[ In theory you could, of course, what with a small co-shafted VC that
removes capacitance from the main LC as the throttle cap adds it, but
it must be a pretty complicated law, and I don't know of anyone who
tried it :) ]

You can instead turn to the gain-control way, DC-controlling one of the
following:
- second grid voltage in a pentode
- plate voltage in a triode
- base voltage in a transistor
or some such like.

All of the above minimize frequency change especially in tube designs
(where varicap effects are basically nonexistent), but can suffer from
annoying hysteresis, in my experience more than cap throttle. Not sure
where the "high performance" advantage of cap throttle is though...

Another trick I wish I had tried is changing a *stabilized* voltage, as
opposed to using a simple throttle pot. That could be done with a
variable regulator IC and might remediate the hysteresis.

Another trick is to use a couple of effects working in opposite
directions, such as a resistive throttle that adds gain but shunts more
RF to ground, such as in the Charles Kitchin "Beginner's Radio".

See www2.arrl.org/tis/info/HTML/regen/
with many derivatives linked in this article of mine:
http://www.geocities.com/filippo_cat...sert-ratt.html .

I think the same trick may be in use in the MFJ-8100 regen, but I can't
tell what's trimmer and what's main control pot.
(hand drawn schematic may be he
www.diagram.com.ua/list/mogik.shtml
sorry Martin!).

So, there's hope.