Re: Finding an AGC circuit with fast/slow attack
or you could do
worse than check out the IF AGC (and S Meter) approach used by
Eamon Skelton EI9GQ in his various rig designs. A google
seatrch will find them. I intend to use one of his designs,
which are all generally similar and also echo the "epitome" IF
AGC design that Ashar champions.
Bill, VK7MX
On 9/03/2017 7:33 AM, William Kimber
wrote:
toggle quoted message
Show quoted text
Somewhen in the past there was a version of the SL621 AGC
circuit made with individual transistors.? Try searching the
RSGB handbook or tech topics.
Cheers,
William
On 03/09/2017 08:38 AM, Doug - via
Groups.Io wrote:
Chuck,
? I am very interested in an AGC circuit for the BITX40. I
have already installed a new audio output amp - LM386 - that
works substantially better but on strong signals and a good
antenna there is distortion from some point onboard. Having to
ride the volume is a pain in the you know what. I was looking
at my radio-engineer handbook and one of the AGC circuits they
show uses the Plessy Sl621 AGC chip. I doubt it is still
available but if it was it would make things very simple.
Google it, the PDF data is still out there. This uses audio to
establish AGC that could be applied in some way to probably Q1
on the BITX board.
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|
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Hi
Not really sure. These are the numbers that I have collected.
Randy, K7AGE
| BITX40 Deliveries – Randy, K7AGE 3/8/17 |
|
|
|
|
|
|
SN |
Ordered |
Shipped |
Arrived |
Num of Days |
| VE3MIC |
412 |
10/24/16 |
|
11/17/16 |
24 |
| K7AGE |
02-139 |
12/23/16 |
12/29/16 |
1/9/17 |
17 |
| 4X4LF |
02-213 |
12/12/16 |
|
1/23/17 |
42 |
| K4RJJ |
234 |
|
|
|
|
| KE0OG |
02-607 |
1/11/17 |
|
2/7/17 |
27 |
| DM1VA |
02-734 |
1/13/17 |
|
2/6/17 |
24 |
| KF4FGI |
02-782 |
|
|
2/3/17 |
|
| AndyH |
02-869 |
|
|
|
|
| W7DKO |
02-925 |
About two weeks |
|
02/22/22 |
|
| KI6SSI |
2-929 |
02/03/17 |
|
02/21/17 |
18 |
| Richard |
02-945 |
|
|
2/13/17 |
|
| AG7CT |
02-953 |
1/22/17 |
|
|
|
| K3RLL |
02-970 |
1/26/17 |
|
2/9/17 |
14 |
| Bill Uebele |
F3-1718 |
2/8/17 |
|
3/4/17 |
24 |
| KM4WII |
43-228 |
2/12/17 |
|
3/7/17 |
23 |
On Wed, Mar 8, 2017 at 10:40 AM, Thomas Noel <tnoel@...> wrote: Just a running total of how wildly successful this device has become.
On Mar 8, 2017, at 9:57 AM, Daniel Acevedo < dan.ace86@...> wrote:
Just curious, what does the serial number tell you?
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Re: Finding an AGC circuit with fast/slow attack
The audio amp with AGC as seen in the uBitx could be a good addition to the Bitx40. ?That amp will have less distortion than the LM386. ? If you want to know what's involved for really good AGC, follow the link in this post: ?/g/BITX20/message/22670??
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Re: Finding an AGC circuit with fast/slow attack
hi all,
The SL621 works from the audio but controls the RF/IF. It has
fast attack, to reduce the signal, a longish hang time to cope
with inter-word/sentence gaps and then rapid decay to rapidly
bring gain back up to full.
Personally I would prefer to control IF and/or RF rather than
detected audio.? Controlling AF creates risk of overload in
IF/detector.?
Cheers,
Will?
On 03/09/2017 11:21 AM, John Baggott
wrote:
toggle quoted message
Show quoted text
Hi,
On most discreet AGC circuits tis a Diode that feeds a resistor
capacitor pair, it is the time constant (t = R * C ) that
determines how fast or slow the AGC will work, it would be easy
to replace the fixed resistor with a pot and experiment , if you
can not get it slow enough increase teh capacitor value.
Cheers
On Wed, Mar 8, 2017 at 5:02 PM Marc Jones via
Groups.Io <gw0wvl= [email protected]>
wrote:
Why not use
a NE570 compressor as a AGC ..??
Regards?
On Wed, 8 Mar 2017 at 21:34, Doug -
via Groups.Io
I found the following most
interesting articles in a Google search -
I did not see anything about the
discrete equiv. for the SL621.
I have not had a chance to go
through them yet. I also need to look at my many ARRL
handbooks. There are discrete AGC circuits defined.
The circuit is not as much the problem as how to apply
the AGC to the BITX. For ease of use I would use audio
AGC so two connections to the existing board would be
all that is needed.? Not looking for perfect just a
lot better than it is now.
I also don't want to reinvent the
wheel. If this has already been done or anyone has any
ideas please pass it on.
I emailed a ham who apparently used
the Plessy SL621 in a recent homebrew receiver design.
I suspect he had it in his junkbox but if this is
still an available chip somewhere it would make things
a lot easier.
--
|
Here is a link to my recent Bitx40 build -
http://crompton.com/hamradio/bitx40/
|
Re: Finding an AGC circuit with fast/slow attack
Hi, On most discreet AGC circuits tis a Diode that feeds a resistor capacitor pair, it is the time constant (t = R * C ) that determines how fast or slow the AGC will work, it would be easy to replace the fixed resistor with a pot and experiment , if you can not get it slow enough increase teh capacitor value.
Cheers
On Wed, Mar 8, 2017 at 5:02 PM Marc Jones via Groups.Io <gw0wvl= [email protected]> wrote: Why not use a NE570 compressor as a AGC ..??
Regards?
On Wed, 8 Mar 2017 at 21:34, Doug - via Groups.Io I found the following most interesting articles in a Google search - I did not see anything about the discrete equiv. for the SL621.
I have not had a chance to go through them yet. I also need to look at my many ARRL handbooks. There are discrete AGC circuits defined. The circuit is not as much the problem as how to apply the AGC to the BITX. For ease of use I would use audio AGC so two connections to the existing board would be all that is needed.? Not looking for perfect just a lot better than it is now.
I also don't want to reinvent the wheel. If this has already been done or anyone has any ideas please pass it on. I emailed a ham who apparently used the Plessy SL621 in a recent homebrew receiver design. I suspect he had it in his junkbox but if this is still an available chip somewhere it would make things a lot easier.
|
Re: Finding an AGC circuit with fast/slow attack
Why not use a NE570 compressor as a AGC ..??
Regards?
On Wed, 8 Mar 2017 at 21:34, Doug - via Groups.Io <dsc3507@...> wrote: I found the following most interesting articles in a Google search - I did not see anything about the discrete equiv. for the SL621.
I have not had a chance to go through them yet. I also need to look at my many ARRL handbooks. There are discrete AGC circuits defined. The circuit is not as much the problem as how to apply the AGC to the BITX. For ease of use I would use audio AGC so two connections to the existing board would be all that is needed.? Not looking for perfect just a lot better than it is now.
I also don't want to reinvent the wheel. If this has already been done or anyone has any ideas please pass it on. I emailed a ham who apparently used the Plessy SL621 in a recent homebrew receiver design. I suspect he had it in his junkbox but if this is still an available chip somewhere it would make things a lot easier.
|
Probably W1AW code practice. Mine did the same!
73, Bob KI0G?
toggle quoted message
Show quoted text
On Mar 8, 2017, at 3:51 PM, Daniel Acevedo < dan.ace86@...> wrote: Nice. I just heard today that these little boars are antennas themselves! How was the audio with an antenna?
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Nice. I just heard today that these little boars are antennas themselves! How was the audio with an antenna?
On Mar 8, 2017 1:47 PM, "Steve Black via Groups.Io" <kb1chu= [email protected]> wrote: I took my new Bitx40 out of my shack to show my wife right after it was finished. As soon as I hooked it up to a 12 volt battery it came to life and I heard real slow morse. So slow I could follow it. The funny part is that no antenna was connected. As soon as it appeared it was gone. I got a tiny bit of the conversation but no calls. Steve KB1CHU?
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I took my new Bitx40 out of my shack to show my wife right after it was finished. As soon as I hooked it up to a 12 volt battery it came to life and I heard real slow morse. So slow I could follow it. The funny part is that no antenna was connected. As soon as it appeared it was gone. I got a tiny bit of the conversation but no calls. Steve KB1CHU?
|
Re: Finding an AGC circuit with fast/slow attack
I found the following most interesting articles in a Google search - I did not see anything about the discrete equiv. for the SL621.
I have not had a chance to go through them yet. I also need to look at my many ARRL handbooks. There are discrete AGC circuits defined. The circuit is not as much the problem as how to apply the AGC to the BITX. For ease of use I would use audio AGC so two connections to the existing board would be all that is needed.? Not looking for perfect just a lot better than it is now.
I also don't want to reinvent the wheel. If this has already been done or anyone has any ideas please pass it on. I emailed a ham who apparently used the Plessy SL621 in a recent homebrew receiver design. I suspect he had it in his junkbox but if this is still an available chip somewhere it would make things a lot easier.
|
Re: Finding an AGC circuit with fast/slow attack
Folks,
I made simulations on a "discrete version" of the SL611
(component values from the Plessey 1975 data book) using LTSPICE
and then upon success with teh simulaiton I also made a pcb
layout. There is also a discrete version of the SL621 as a layout
(I am using EASY PC). For unknown reasons I can not upload the pdf
files into my folder (DK5LVs stuff)
Can somebody advise how to upload?
Henning
DK5LV
Am 08.03.2017 um 21:33 schrieb William
Kimber:
toggle quoted message
Show quoted text
Somewhen in the past there was a version of the SL621 AGC
circuit made with individual transistors.? Try searching the
RSGB handbook or tech topics.
Cheers,
William
On 03/09/2017 08:38 AM, Doug - via
Groups.Io wrote:
Chuck,
? I am very interested in an AGC circuit for the BITX40. I
have already installed a new audio output amp - LM386 - that
works substantially better but on strong signals and a good
antenna there is distortion from some point onboard. Having to
ride the volume is a pain in the you know what. I was looking
at my radio-engineer handbook and one of the AGC circuits they
show uses the Plessy Sl621 AGC chip. I doubt it is still
available but if it was it would make things very simple.
Google it, the PDF data is still out there. This uses audio to
establish AGC that could be applied in some way to probably Q1
on the BITX board.
|
Re: Finding an AGC circuit with fast/slow attack
Somewhen in the past there was a version of the SL621 AGC circuit
made with individual transistors.? Try searching the RSGB handbook
or tech topics.
Cheers,
William
On 03/09/2017 08:38 AM, Doug - via
Groups.Io wrote:
toggle quoted message
Show quoted text
Chuck,
? I am very interested in an AGC circuit for the BITX40. I have
already installed a new audio output amp - LM386 - that works
substantially better but on strong signals and a good antenna
there is distortion from some point onboard. Having to ride the
volume is a pain in the you know what. I was looking at my
radio-engineer handbook and one of the AGC circuits they show
uses the Plessy Sl621 AGC chip. I doubt it is still available
but if it was it would make things very simple. Google it, the
PDF data is still out there. This uses audio to establish AGC
that could be applied in some way to probably Q1 on the BITX
board.
|
Added a Wiki Cheat Sheet to help anyone that may want to contribute to the Wiki. Bottom topic on the first page.
James
|
Re: Finding an AGC circuit with fast/slow attack
Chuck, ? I am very interested in an AGC circuit for the BITX40. I have already installed a new audio output amp - LM386 - that works substantially better but on strong signals and a good antenna there is distortion from some point onboard. Having to ride the volume is a pain in the you know what. I was looking at my radio-engineer handbook and one of the AGC circuits they show uses the Plessy Sl621 AGC chip. I doubt it is still available but if it was it would make things very simple. Google it, the PDF data is still out there. This uses audio to establish AGC that could be applied in some way to probably Q1 on the BITX board.
|
|
|
Just curious, what does the serial number tell you?
|
I bought a wall wart, cheep when if first got my BITX40.. from ALLELECTRONICS.COM because-- always a because --it was cheep, had the power connector on it and-----AND--- I also needed to order other items for my build ---and ALLECLECTONICS.COM had them.. Matching knobs both 1/8 and 1/4 diameter for the pots, a speaker, and other odds and ends.. such a 12MHz crystals 4 for a $1....which I will experiment with the BITX40. They have a flat rate shipping so.. The point I am making is that I've been using that wall wart since...you can't but the parts to build one for what I got this.. Besides if I get ambitious, venturing further, a battery based system would be in order..
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Re: uBITX - A reboot of the old BITX
PDF will be best for home brewing Regards Lawrence
On Tue, Mar 7, 2017 at 1:25 PM, John VA7JBE via Groups.Io <va7jbe@...> wrote: As much as I'd love to see a kit for the uBitX released it may not be feasible in the immediate future.? Instead it might be more realistic to create and release things like PCB gerber files, BOMs, and Kicad project files to make it easier for new homebrewers to tinker with the schematic and layout.? Different files for SMD and through hole components would be relatively simple to do.? There will undoubtedly be people who release their own files, as has happened with the BitX20, but having a foundation to work from would be a great start for those who don't have much experience with these things.
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K2BAG
Marc Jones