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Duh-oo


Jack, W8TEE
 

My bad, it should have read:

Again, I'm not an EE type, but if the metering is done off the volume control, is it really an  S meter or a VU meter??

Jack, W8TEE


On Wednesday, October 28, 2020, 1:26:27 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


The signal off the volume control can be used as a signal source for either S-meter purposes OR a way to control an AGC circuit by causing attenuation for signals above a pre-set level. However, I learned with my G90 that there are times when the AGC should be shut off to provide maximum signal gain.

Bob — KK5R

On Wednesday, October 28, 2020, 12:56:25 PM EDT, Jack, W8TEE via groups.io <jjpurdum@...> wrote:


Again, I'm not an EE type, but if the metering is done off the volume control, is it really an SWR meter or a VU meter??

Jack, W8TEE

On Wednesday, October 28, 2020, 12:49:45 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


This again is offered to show an S-meter circuit borrowed from the transceiver circuit being sold from Indonesia. It is apparently attachable to the volume control and since it's in the receive system, it does not affect the transmit system. It can be "rubbered" here and there since the component values may be the best for this considering that they are what is available to the builders in Indonesia, the FET and transistor can work equally well when using substitutes. Attaching to the high end of the uBITX's volume control and making the 47K variable in the circuit below a set resistor for calibration purposes results in making this a usable circuit. The meter, of course, can be substituted with an LED barcode circuit OR merely provide a source signal for an on-screen display of received signal level. The circuit as shown is relatively simple, however.

Bob — KKR

Inline image


On Wednesday, October 28, 2020, 7:06:58 AM EDT, IW4AJR Loris <lorisbollina@...> wrote:


On the CCARC (Carroll County Amateur Radio Club, Inc.) website I found a very interesting article on automatic gain control that is worth reading!
Without many frills Carol makes us understand that an AGC (automatic gain control) on the IF of the uBITX, due to the nature of the amps used (bidirectional), is very complex to make at this level of the circuit ...
therefore ? ...
Much better and less invasive to act directly on the volume control, implementing a simple but effective automatic volume control (AVC)!
Think man ... think ...
A little less software and a little more electronic experimentation and, with much less effort, very complex problems can be solved!
Think man ... think !
Greetings to all, Loris IW4AJR

--
Jack, W8TEE

--
Jack, W8TEE


Bob Lunsford
 

Everything is relative. One's S-meter reading depends on the receiver AND the antenna. One too many variables. A Volume Unit reading is based on voltage across a standard resister value. The VU reading may be more accurate but still has too many variables.

Personally, I do not need an S-meter and unless someone asks me, I do not give a Signal Strength report. It means little to me when we are talking about readability.

I can come up with a circuit that may warm someone's heart but my V6 does not need an S-meter. HOWEVER, the same circuit can be an operator for the AGC circuit. Old time operators used to pull the "cans" off the ears and put them over the temple to either adjust the audio level or keep excessive volume from waking them up. Been there, done that...

Bob — KK5R



On Wednesday, October 28, 2020, 2:26:54 PM EDT, Jack, W8TEE via groups.io <jjpurdum@...> wrote:


My bad, it should have read:

Again, I'm not an EE type, but if the metering is done off the volume control, is it really an  S meter or a VU meter??

Jack, W8TEE


On Wednesday, October 28, 2020, 1:26:27 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


The signal off the volume control can be used as a signal source for either S-meter purposes OR a way to control an AGC circuit by causing attenuation for signals above a pre-set level. However, I learned with my G90 that there are times when the AGC should be shut off to provide maximum signal gain.

Bob — KK5R

On Wednesday, October 28, 2020, 12:56:25 PM EDT, Jack, W8TEE via groups.io <jjpurdum@...> wrote:


Again, I'm not an EE type, but if the metering is done off the volume control, is it really an SWR meter or a VU meter??

Jack, W8TEE

On Wednesday, October 28, 2020, 12:49:45 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


This again is offered to show an S-meter circuit borrowed from the transceiver circuit being sold from Indonesia. It is apparently attachable to the volume control and since it's in the receive system, it does not affect the transmit system. It can be "rubbered" here and there since the component values may be the best for this considering that they are what is available to the builders in Indonesia, the FET and transistor can work equally well when using substitutes. Attaching to the high end of the uBITX's volume control and making the 47K variable in the circuit below a set resistor for calibration purposes results in making this a usable circuit. The meter, of course, can be substituted with an LED barcode circuit OR merely provide a source signal for an on-screen display of received signal level. The circuit as shown is relatively simple, however.

Bob — KKR

Inline image


On Wednesday, October 28, 2020, 7:06:58 AM EDT, IW4AJR Loris <lorisbollina@...> wrote:


On the CCARC (Carroll County Amateur Radio Club, Inc.) website I found a very interesting article on automatic gain control that is worth reading!
Without many frills Carol makes us understand that an AGC (automatic gain control) on the IF of the uBITX, due to the nature of the amps used (bidirectional), is very complex to make at this level of the circuit ...
therefore ? ...
Much better and less invasive to act directly on the volume control, implementing a simple but effective automatic volume control (AVC)!
Think man ... think ...
A little less software and a little more electronic experimentation and, with much less effort, very complex problems can be solved!
Think man ... think !
Greetings to all, Loris IW4AJR

--
Jack, W8TEE

--
Jack, W8TEE


Curt
 

Let's see you guys are making too much of this -- the meter operation was an after thought in the scheme of this AGC. 

Certainly there is no log response in this circuit that an S-meter needs.  The function is this - the audio is sampled and amplified, fed to an ordinary silicon diode - and this drives a transistor with a dc bias in linear fashion (more or less) that feeds an LED.  The current through the LED is measured using an ammeter shunted with a small appropriate resistor (4.7 ohms for the meter that Sunil shipped).  That's it for the meter.  (possibly the brightness of this LED may be a better measure of signal strength than meter deflection perhaps).  I need to make a couple updates to the AGC schematic - but it is very similar to what VK3YE sketched out.  It works nice enough in this transceiver to suppress big signals.  I will caution that the behavior needs some tweaking to actual LED and LDR parts - but it works nicely. 

73 curt


Bob Lunsford
 

It appears that we are talking about two different circuits, causing even more confusion.

Going back to making soup. {;->

Bob — KK5R

On Wednesday, October 28, 2020, 8:07:12 PM EDT, Curt via groups.io <wb8yyy@...> wrote:


Let's see you guys are making too much of this -- the meter operation was an after thought in the scheme of this AGC. 

Certainly there is no log response in this circuit that an S-meter needs.  The function is this - the audio is sampled and amplified, fed to an ordinary silicon diode - and this drives a transistor with a dc bias in linear fashion (more or less) that feeds an LED.  The current through the LED is measured using an ammeter shunted with a small appropriate resistor (4.7 ohms for the meter that Sunil shipped).  That's it for the meter.  (possibly the brightness of this LED may be a better measure of signal strength than meter deflection perhaps).  I need to make a couple updates to the AGC schematic - but it is very similar to what VK3YE sketched out.  It works nice enough in this transceiver to suppress big signals.  I will caution that the behavior needs some tweaking to actual LED and LDR parts - but it works nicely. 

73 curt


Jack, W8TEE
 

I have a T-shirt that says:

    In my defense, I was left unsupervised

Kinda true for me, since I don't know much about the circuits in the uBITX. However, when Al and I did the JackAl DSP code, we had a AGC in it and we also had an S-meter. Peter's AGC works as I implemented a version for an early BITX I had. However, it is different than the AGC the JackAl has.

BTW, the schematics for the JackAl and its software are Open Souce and available on my SoftwareControlledHam Radio site.

Jack, W8TEE

On Wednesday, October 28, 2020, 8:07:18 PM EDT, Curt via groups.io <wb8yyy@...> wrote:


Let's see you guys are making too much of this -- the meter operation was an after thought in the scheme of this AGC. 

Certainly there is no log response in this circuit that an S-meter needs.  The function is this - the audio is sampled and amplified, fed to an ordinary silicon diode - and this drives a transistor with a dc bias in linear fashion (more or less) that feeds an LED.  The current through the LED is measured using an ammeter shunted with a small appropriate resistor (4.7 ohms for the meter that Sunil shipped).  That's it for the meter.  (possibly the brightness of this LED may be a better measure of signal strength than meter deflection perhaps).  I need to make a couple updates to the AGC schematic - but it is very similar to what VK3YE sketched out.  It works nice enough in this transceiver to suppress big signals.  I will caution that the behavior needs some tweaking to actual LED and LDR parts - but it works nicely. 

73 curt

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Jack, W8TEE