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Author Topic: Super regenerative receiver : how to improve the quench ?  (Read 387 times)

F1CUJ

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Super regenerative receiver : how to improve the quench ?
« on: November 14, 2021, 10:58:19 AM »

Hi,

I have built 3 different solid state super regenerative receivers for the aircarft band.

Unfortunately, it is very difficult to find information to improve the prformance.
Here are my specific questions about quench :

1- Is increasing the quench frequency improving or not the  receiver sensitivity ? I have tested different frequencies from 10 kHz to 300 kHz. As the messages are very short, it is difficult to make a difference ...

2. What is the maximum quench frequency to use to have the best sensitivity ?

3. Some patents (Not readable) say that "key receiver performance is intricately tied to the quench wave shape. . It seems that a sine wave is better than a sine wave ? Why ?

4. The performance is better when the circuit is not self-quenched but using a separate quench oscillator. So I don't know how to connect an oscillator to my existing circuit

Thanks for your help

Philippe

P/S I didn't find the solution to embed the circuit image here !...
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G3RZP

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #1 on: November 15, 2021, 03:44:40 AM »

Philippe,

There was a good article on Super regenerative receivers under the pseudonym 'Cathode Ray' in Wireless World, for the June 1946 edition. P182 and following pages.  You can find it at : https://worldradiohistory.com/UK/Wireless-rld/40s/Wireless-World-1946-06.pdf 

There is correspondence on the  this in the August 1946 Edition Correspondence column and a reference to the Proc. I. R. E. for October 1944 to an article by Kalmus.

I hope this information  helps.

73

Peter G3RZP
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F1CUJ

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #2 on: November 15, 2021, 04:49:10 AM »

Hello Peter

Sorry the link doesn't work error 404 ...

73
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WA6NUT

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F1CUJ

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #4 on: November 15, 2021, 07:33:10 AM »

Hi Rick

Yes it's OK !
Thank you

Unfortunately I have never used tubes :-)

My receiver uses 2N 2369 A.

Otherwise, any suggestion concerning my 4 questions above ?

I don't know how it is possible to embed my schematic here ...

73
Philippe
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G3RZP

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #5 on: November 16, 2021, 12:15:51 AM »

Philippe,

the principles are the same, no matter what the devices are.
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G3RZP

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #6 on: November 16, 2021, 06:50:19 AM »

Philippe,

1. Use a sine wave quench (this will give best selectivity), with a separate quench oscillator
2. Quench frequency should be related to highest modulating frequency of the received signal, so about 10 to 15kHz should be about optimum - the lower the QF, the better the sensitivity.
3.  Make the feedback for detector such as to have it oscillate strongly.
4.  Make the quench level variable, and use the minimum quench level that allows the circuit to work adequately.
5.  Especially if using the rx near an airfield, use a cascode RF amplifier (for reverse isolation) and a lot of screening to avoid causing interference
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F1CUJ

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #7 on: November 16, 2021, 08:36:33 AM »

Philippe,

1. Use a sine wave quench (this will give best selectivity), with a separate quench oscillator
2. Quench frequency should be related to highest modulating frequency of the received signal, so about 10 to 15kHz should be about optimum - the lower the QF, the better the sensitivity.
3.  Make the feedback for detector such as to have it oscillate strongly.
4.  Make the quench level variable, and use the minimum quench level that allows the circuit to work adequately.
5.  Especially if using the rx near an airfield, use a cascode RF amplifier (for reverse isolation) and a lot of screening to avoid causing interference

Hello Peter !

Thank you so much it is the first time I have a clear and concise answer.

Here are my remarks :
1 - A sine wave : why is it better ? On other forums, I have seen that no matter the waveform of the quench, but it is difficult to believe ... OK for a separate quench oscillator I have already started to test a sawtooth one
2- Quench frequency : the lower the QF, the better the sensitivity : Why ? Do you mean that the transistor (2N 2369 A) has a lower "workload" ? :-)
3- OK !
4- Quench level : OK I agree
5- OK but does it decrease the sensitivity or not ?

I would like to show you the schematic but I have asked the webmaster, alas no way to embed an image in the message !

Again thank you for your help
Best regards
Philippe
F1 CUJ
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G3RZP

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #8 on: November 16, 2021, 12:53:35 PM »

Philippe

READ THE REFERENCE TO THE WIRELESS WORLD ARTICLE!!!!

That explains why, and it is NOT limited to tube circuits!

A sinewave is better because it allows a slower build up and decay.  READ THE REFERENCE!


2. Quench frequency should be related to highest modulating frequency of the received signal, so about 10 to 15kHz should be about optimum - the lower the QF, the better the sensitivity.   Because it allows more time for the signal to build up..READ THE REFERENCE!


5.  Especially if using the rx niear an airfild, use a cascode RF amplifier (for reverse isolation) and a lot of screening to avoid causing interference
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G3RZP

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #9 on: November 16, 2021, 12:58:55 PM »

Quote
5.  Especially if using the rx niear an airfild, use a cascode RF amplifier (for reverse isolation) and a lot of screening to avoid causing interference

Because if you don't, you may get a lot of very p*ssed off policeman and security guards pointing submachine guns at you before you get hauled off to prison! But it could well improve sensitivity...
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KM1H

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #10 on: November 16, 2021, 03:11:20 PM »

My only super regen was a Heath Sixer used mobile while commuting  P U

A used Clegg 66er was a huge improvement in my 57 Chebby
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K0UA

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #11 on: November 16, 2021, 10:06:20 PM »

Quote
I would like to show you the schematic but I have asked the webmaster, alas no way to embed an image in the message !

Imbedding images here is quite easy to do. It has been posted hundreds of times. But if you like just send the image to me and I will imbed it for you.

James K0UA

Here is a schematic to show you that it can be easily done.

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73  James K0UA

F1CUJ

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #12 on: November 17, 2021, 12:46:28 AM »

Philippe

READ THE REFERENCE TO THE WIRELESS WORLD ARTICLE!!!!

That explains why, and it is NOT limited to tube circuits!

A sinewave is better because it allows a slower build up and decay.  READ THE REFERENCE!


2. Quench frequency should be related to highest modulating frequency of the received signal, so about 10 to 15kHz should be about optimum - the lower the QF, the better the sensitivity.   Because it allows more time for the signal to build up..READ THE REFERENCE!


5.  Especially if using the rx niear an airfild, use a cascode RF amplifier (for reverse isolation) and a lot of screening to avoid causing interference

Hello Peter

You were right to insist on reading more carefully the Wireless article.

I have found as you said it before some relevant information page 185 at the chapter 6 concerning the sine wave choice for the quench.

So I have now to build a sine wave oscillator with a level control and make some tests  :)

Thank you !
Philippe
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F1CUJ

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Re: Super regenerative receiver : how to improve the quench ?
« Reply #13 on: November 24, 2021, 05:03:42 AM »

Quote
I would like to show you the schematic but I have asked the webmaster, alas no way to embed an image in the message !

Imbedding images here is quite easy to do. It has been posted hundreds of times. But if you like just send the image to me and I will imbed it for you.

James K0UA


Hi James

Sorry to answer so late but I was extremely busy.

It is nice from you but may I ask you how to do it ?
Yhank you
73
Philippe
Here is a schematic to show you that it can be easily done.


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