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Author Topic: Why Regen's?  (Read 717 times)

N7EKU

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Re: Why Regen's?
« Reply #15 on: November 18, 2021, 02:20:42 PM »

In my teens I tinkered with a "Super Regen receiver, but today I'm wondering why play/work with them? (This from a DC lover?? LOL)

I recall they were really sensitive and a bit touchy as far as tuning goes, which is probably no problem with today's projects.

What is the attraction now? Just wondering.

Charlie

I would say that they offer superior fidelity to the typical low-cost DC or superhet receiver, one simple circuit can receive AM, CW, FM and SSB, they still work well at VHF and beyond, and a superregenerative circuit will provide built-in AGC action.

73.
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Mark -- N7EKU/VE3

KM1H

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Re: Why Regen's?
« Reply #16 on: November 18, 2021, 03:02:20 PM »

Quote
I would say that they offer superior fidelity to the typical low-cost DC or superhet receiver, one simple circuit can receive AM, CW, FM and SSB, they still work well at VHF and beyond, and a superregenerative circuit will provide built-in AGC action.


OH?  On CW they were poor due to the regen selectivity on crowded Novice bands, on AM the sensitivity was poor if good audio was wanted. I listened to a lot of 10M AM during the Cycle 19 ramp up; that HB RX with AA-5 tubes also had a 12SK7 RF amp and 50L6 audio, all tubes plus other useable parts came from a local dump.

The typical AA-5 with its barn door IF selectivity sounded excellent on AM.

Carl
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N7EKU

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Re: Why Regen's?
« Reply #17 on: November 18, 2021, 04:27:07 PM »

I guess I always had a loooong wire antenna on mine so sensitivity was not a problem,

Mostly I was thinking about SWL and to my ears they sound better and I've found that they do have a nice AGC action.  Maybe not superior performance, as for sure CW is not the easiest (and I don't have the Novice experience of trying one on a crowded CW band!), but a lot of modes for a three transistor circuit.

And I'm sure your homebrew tube receiver sounds great!

73


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Mark -- N7EKU/VE3

KL7CW

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Re: Why Regen's?
« Reply #18 on: November 19, 2021, 05:22:24 PM »

My experience was that regens offered good performance for a simple circuit with only 2 or 3 active devices.  On CW even in the crowded novice bands of the 1950's they worked "OK" even as long as no very local novices lived within a few blocks, and even then I could sometimes get by.  My experience was that they could often work OK with a rather short random wire antenna, like for portable operation.  A full size 40 meter dipole tightly coupled to the RX was just too much.  We often just used a "gimmick" capacitor of a few PF to couple the RF into the receiver and this "solved" many overload problems. (the capacitor was just an inch or so of 2 wires twisted together a few times). Also back then nearly zero percent of the novice population had good commercial receivers with any significant selectivity, so we could hear a good percentage of the audio spectrum at one time, perhaps all the way from much less than 100 Hz to possibly 10 KHz.  We fully developed our brain filters and could copy many different CW signals 100 % without touching the dial. This did have it's limits !!!.  Years later we discovered Q multipliers, 50 KHz IF amps for our "creations", and even the crystal filter, which made single signal reception possible. The 40 meter novice band back around 1954 and 1955 was only 25 KHz wide and had thousands of stations every evening, and our transmitters were crystal controlled, so after a CQ we would tune up the band slowly and often find an answer 5, 10 or more KHz above our transmit frequency. One thousand mile QSO's common, but coast to coast QSO's were not rare, and many novice ops. with perhaps 25 watts, a dipole, and only a few crystals obtained WAS certificates.  I now appreciate my crystal filters where I can listen to one signal at a time, but for casual operation still just use my 700Hz or 2700 Hz filter for casual operation since I like to know what is happening up and down the band a bit.  I got off the regen topic, but it is important for CW operation to set the regen control just at the point where oscillation just begins.  This gives some moderate selectivity, but in our old crude regen circuits, moving the frequency slightly also required a re adjustment of the regen control.   Long live the regen   KL7CW
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G3EDM

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Re: Why Regen's?
« Reply #19 on: November 23, 2021, 01:48:01 PM »

Just an update folks. I've been on the air (for the first time) for nearly three months and have nearly 60 QSOs, 15 countries, and a lot of fun along the way as I learn to operate and try to improve my Morse.

The rig is a two-tube MOPA at about 7 watts output, and a seven-tube regenerative receiver (the heart of the receiver is just three tubes: RF stage, detector, first AF).

So it's doable. As I said in my earlier post, it was a highly productive experiment. As a long-term receiver setup: probably not.

73 de Martin, G3EDM
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KB1GMX

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Re: Why Regen's?
« Reply #20 on: November 24, 2021, 02:55:37 PM »

With regens the basic ones are centered on keeping parts
count low .  They do work.  They also have their limits.

I have to admit at 7 tubes Im running superhet with crystal filters.

Over 5 decades I've built a lot of regens using all manor of gain
devices to accomplish regeneration.  The one that survived to
this day is a simple 3 tubes ( 4 for speaker audio output).
The front end was a 6u8a or 6be6 converter (mixer
and VFO in one tube) outputting to lower frequency
(like 400khz) to a regenerative detector using a low gain
tube like 6c4 or half 12au7.  The other half of the 12au7
can be used for audio amp.

same deal with battery tube and solidstate:
1R5, 1t4, 1t4  (many possible combinations)
12ad6, 12ek5, 12ek5  (12v plate tubes, and many "normal" ones')
or 4 2n3904s or a mix of those and MPF102s.

The converter keep the regen output from radiating via the
antenna and also allows the regen detector to run at MW
or LF where it can be both fixed and very stable.

The result is adequately stable and selective compared to
a bare regen.  Its solve all of the stability issues (hand
capacity) and a fixed tuned regen is easier to manage
when tuning across a band or several.


Allison
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G3RZP

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Re: Why Regen's?
« Reply #21 on: November 25, 2021, 01:54:04 AM »

Allison,

That arrangement used to be known over here prior to WW2 as a "Super-Gainer". By making the regen part tuneable over a narrow range, you could, at the expense of more complexity in tuning, adjust the frequencies to avoid problems with images - which, with  superhet with a fixed 455kHz IF, you couldn't!

I found the best tube for a detector was a 6BA6, with variable screen voltage for control of regeneration....the sharp cut off, high gain tubes for TV IF strips were much harder to get smooth regeneration from.
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KB1GMX

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Re: Why Regen's?
« Reply #22 on: November 26, 2021, 04:23:00 PM »

I know supergainer and have built them...

What I referred to is reverse of that, tuneable converter feeding
fixed regen (IF).The regen control is retained for gain and BFO
(CW) but the stage is fixed at some low and handy frequency.
The upside is the regen did not need constant adjustment
while tuning.

That also appeared in the handbooks.  THe 1957 handbook
had that.


Allison
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G3EDM

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Re: Why Regen's?
« Reply #23 on: November 29, 2021, 12:33:59 PM »

Allison,

That arrangement used to be known over here prior to WW2 as a "Super-Gainer". By making the regen part tuneable over a narrow range, you could, at the expense of more complexity in tuning, adjust the frequencies to avoid problems with images - which, with  superhet with a fixed 455kHz IF, you couldn't!

I found the best tube for a detector was a 6BA6, with variable screen voltage for control of regeneration....the sharp cut off, high gain tubes for TV IF strips were much harder to get smooth regeneration from.

I know supergainer and have built them...

What I referred to is reverse of that, tuneable converter feeding fixed regen (IF).The regen control is retained for gain and BFO (CW) but the stage is fixed at some low and handy frequency. The upside is the regen did not need constant adjustment while tuning.

That also appeared in the handbooks. The 1957 handbook had that.

Allison

Peter, Allison:

Then there is the article by Lew McCoy in the July 1963 issue of QST describing the "Novice RS-3". I actually gathered together the parts for that nearly a decade ago and still have them in a project box: never got around to building it. Into which of the superhet/regenerative combo categories does this one fit? Do you think it is worth building, if so what are its advantages and drawbacks?



I am in need of a better receiver and this might be a relatively quick build given that I have the components. But would it provide any appreciable improvement compared to my "straight" regenerative receiver (using subminiature tubes), built with help from both of you about seven years ago?

Since I got on the air  three months ago for the first time ever, I've achieved 67 QSOs using that receiver and a crystal-controlled, 7W tube MOPA, but the receiver is as broad as a barn door so what I am really looking for is: a noticeable improvement in selectivity. It does not have to be a stunning improvement ... just something that would make the build worth doing!

This would be a "quick and dirty" project built on the kitchen counter prior to building a "proper" superhet complete with IF filter circuits, several months down the road.

73 de Martin, G3EDM
« Last Edit: November 29, 2021, 12:40:33 PM by G3EDM »
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WB6BYU

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Re: Why Regen's?
« Reply #24 on: November 29, 2021, 01:05:35 PM »

That is a "super-gainer", a super-het receiver with a regenerative
detector at a fixed IF frequency.  That avoids a lot of fiddling with
the regenerative settings when you change frequency.

I think Alison is describing a similar approach.


That's not to say that it will give you any more selectivity, although
the fact that the detector operates at a lower frequency will provide
fewer cycles of bandwidth for the same operating Q.

However, it is possible to add a switched audio filter to any receiver
to provide a narrower receive bandwidth.  That won't provide single-
signal reception of CW, but you can get less than 1 kHz of total
bandwidth rather than 10 kHz or more.

Most common designs for audio filters these days use op amp
integrated circuits, but they can be built with tubes / valves as well.
Generally they would be inserted right before the volume control.

There are some passive LC types as well, which can be as simple as
connecting a capacitor in parallel with the magnetic headphones to
form a resonant circuit at around 600 - 800 Hz.
« Last Edit: November 29, 2021, 01:09:01 PM by WB6BYU »
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G3EDM

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Re: Why Regen's?
« Reply #25 on: November 29, 2021, 01:12:28 PM »

However, it is possible to add a switched audio filter to any receiver to provide a narrower receive bandwidth.  That won't provide single-signal reception of CW, but you can get less than 1 kHz of total bandwidth rather than 10 kHz or more.

Actually my existing regenerative receiver already has one of those, a two-tube circuit based on the ARRL "Audiofil". It works pretty well under the right circumstances. Unfortunately it malfunctioned a few months ago and I have not yet tracked down the fault. It may be something as simple as an error in wiring the switching circuit when the set was rebuilt. I really need to look into that.

There are some passive LC types as well, which can be as simple as connecting a capacitor in parallel with the magnetic headphones to form a resonant circuit at around 600 - 800 Hz.

I have a bunch of those old Bell Co. telephone inductors that are pretty effective, so I've been told, in passive audio filters. That is another thing I can try....

73 de Martin, G3EDM
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WB6BYU

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Re: Why Regen's?
« Reply #26 on: November 29, 2021, 02:57:46 PM »

There were several circuits that used the old 44 / 88 mH toroids.
Simply putting one in series with your headphones and a suitable
capacitor to set the resonant frequency might be a good start.

You probably want some way to bypass the circuit for tuning.


Back in the days when the US Novice class was limited to
crystal controlled transmitters, a wide bandwidth helped to
hear off-frequency calls.  I used to comment that my receiver
covered the whole 50 kHz band on 2 settings of the bandspread
control.  But it certainly is easier to copy when your ears don’t
need to process several other QSOs at the same time.

WB6BYU

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Re: Why Regen's?
« Reply #27 on: November 29, 2021, 03:39:18 PM »

Here are some example passive audio filters using 88mH inductors.

You can find more examples of different types in the Audio Circuits here.

G3RZP

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Re: Why Regen's?
« Reply #28 on: November 30, 2021, 12:57:09 AM »

Just a thought..

100 years plus 12 days ago, Paul Godley 2ZE, had a Paragon regen receiver and a pretty crude superhet. It was the superhet that heard the most signals from the US and on which the first Transatlantic 'short wave' message was received...
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G3EDM

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Re: Why Regen's?
« Reply #29 on: November 30, 2021, 08:07:30 AM »

Just a thought..

100 years plus 12 days ago, Paul Godley 2ZE, had a Paragon regen receiver and a pretty crude superhet. It was the superhet that heard the most signals from the US and on which the first Transatlantic 'short wave' message was received...

Good point! Good articles about this in Radcom this month and last month. (Isn't it 100 years minus 12 days though?)

73 de Martin, G3EDM
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