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Possible S-Meter circuit


Bob Lunsford
 

Found this in an old QST. Could be useful for adopting/adapting to the uBITX for an S-Meter indicator. Previous ideas in the group is to read the voltage at the hot end of the volume control. If not enough voltage, a simple amplifier should make it useful. Sorry it's skewed slightly.

Bob — KK5R

Inline image


IZ4SJP Carlo
 

Bob, did you try it?


Bob, N1KPR
 

Sorry, maybe I'm the wrong Bob...although I was in search of an "s-meter" circuit for the V6.
I designed an analog circuit that tracks the actual signal strength when checked against actual instrumentation (and other receivers). I wanted S9 at 50uV and minus 6dB for every "s unit" below that. The V6 audio bus seems to be perfectly linear (logarithmic in terms of dB) when taken from the hot side of the audio pot.

We have been using LM3914 and -15 chips for years in our off-air monitors and proof of play receivers, but I thought a good-old analog meter would be a nice touch...especially with that legacy amber glow (think tungsten pilot lamp).

I now have the front panel completed.
Attached jpg, but don't know if io groups will pass it...It'll be on youtube shortlet.
Thanks
Bob, N1KPR


Inline image

NOTE Pls add backup address to your phone book: rwbetts@...

http://www.bobsamerica.com  http://www.youtube.com/n1kpr

Engineering: Where Enigma meets Paradox


On Monday, August 10, 2020, 1:06:24 PM EDT, IZ4SJP Carlo <carlo@...> wrote:


Bob, did you try it?


hardrain
 

Hi Bob(s),

Upon suggestion by IZ4SJP, who recommended me the old but valuable article by  R. J. Zavrel,  available here:
https://worldradiohistory.com/Archive-DX/Ham%20Radio/80s/Ham-Radio-198601.pdf
I've been working at the development of a simple but accurate S-Meter for the uBITX using the SA604.
I opted for using an analog meter and built a test circuit. It taps the signal from the volume control but the ic can be used to accurately measure the rf signal.
The prototype worked satisfactorily for me so I've designed a pcb and ordered a couple of them built on Dirtypcb  but I have not received the pcbs yet.
If anyone is interested I can post the diagram.
Anyway since the prototype performs well I can recommend the SA(NE)604 ics for this purpose. They are old stuff but I found them at reasonable price on Ebay. 
Hope this helps.
LM3914-15 work well but they can hardly provide an accurate S- reading. 

Raffaello IZ1HNY

On 10/08/20 19:20, Bob, N1KPR wrote:
Sorry, maybe I'm the wrong Bob...although I was in search of an "s-meter" circuit for the V6.
I designed an analog circuit that tracks the actual signal strength when checked against actual instrumentation (and other receivers). I wanted S9 at 50uV and minus 6dB for every "s unit" below that. The V6 audio bus seems to be perfectly linear (logarithmic in terms of dB) when taken from the hot side of the audio pot.

We have been using LM3914 and -15 chips for years in our off-air monitors and proof of play receivers, but I thought a good-old analog meter would be a nice touch...especially with that legacy amber glow (think tungsten pilot lamp).

I now have the front panel completed.
Attached jpg, but don't know if io groups will pass it...It'll be on youtube shortlet.
Thanks
Bob, N1KPR




NOTE Pls add backup address to your phone book: rwbetts@...

http://www.bobsamerica.com  http://www.youtube.com/n1kpr

Engineering: Where Enigma meets Paradox


On Monday, August 10, 2020, 1:06:24 PM EDT, IZ4SJP Carlo <carlo@...> wrote:


Bob, did you try it?



Bob Lunsford
 

I presented it as something I found in an old CQ magazine. I DID NOT try to imply that I was pushing it or recommending it. In fact, when a built several QRP radios and found a diode across the power leads to short out the power lines if they were connected in reverse, I immediately changed them to be in series with the positive line.

I will not present any new ideas to the group since it encourages thoughts that they are being dragged down, somehow, when at least it causes people to think about it, at least.

Arrivederci, colega.

KK5R

On Monday, August 10, 2020, 1:06:24 PM EDT, IZ4SJP Carlo <carlo@...> wrote:


Bob, did you try it?


hardrain
 

Bob,

I don't think anybody felt you were pushing or recommending anything. I think that if people ask you if you have tested a circuit, they just mean that, because they like to know if and how it works. 
Sometimes sentences from non-native speakers lend themselves to misunderstandings.
LM 39xx s-meters are just as good as any other, performance and accuracy may be different, but we're here to get ideas, test them and share the results according with the Ham spirit I think. So I mentioned my circuit as a contribution related to the topic of the thread.
I definitely encourage you to present ideas to the group again.
By the way, I prefer connecting diodes in series with the positive supply, too ;) 

73
IZ1HNY

On 10/08/20 23:54, Bob Lunsford via groups.io wrote:
I presented it as something I found in an old CQ magazine. I DID NOT try to imply that I was pushing it or recommending it. In fact, when a built several QRP radios and found a diode across the power leads to short out the power lines if they were connected in reverse, I immediately changed them to be in series with the positive line.

I will not present any new ideas to the group since it encourages thoughts that they are being dragged down, somehow, when at least it causes people to think about it, at least.

Arrivederci, colega.

KK5R

On Monday, August 10, 2020, 1:06:24 PM EDT, IZ4SJP Carlo <carlo@...> wrote:


Bob, did you try it?



Bob Lunsford
 

I found out later that Carlo was addressing his question to another Bob. So my comment was indeed out of order.

I wish there were a way to have the comments relate back to the previous comment by a thread link or merely posting the previous comment with the posting comment as is done here. Then the pertinence of a reply could be refreshed in the mind of the reader.

Thanks much for your view on this.

Bob — KK5R

On Tuesday, August 11, 2020, 4:37:36 PM EDT, hardrain <hardrain@...> wrote:


Bob,

I don't think anybody felt you were pushing or recommending anything. I think that if people ask you if you have tested a circuit, they just mean that, because they like to know if and how it works. 
Sometimes sentences from non-native speakers lend themselves to misunderstandings.
LM 39xx s-meters are just as good as any other, performance and accuracy may be different, but we're here to get ideas, test them and share the results according with the Ham spirit I think. So I mentioned my circuit as a contribution related to the topic of the thread.
I definitely encourage you to present ideas to the group again.
By the way, I prefer connecting diodes in series with the positive supply, too ;) 

73
IZ1HNY

On 10/08/20 23:54, Bob Lunsford via groups.io wrote:
I presented it as something I found in an old CQ magazine. I DID NOT try to imply that I was pushing it or recommending it. In fact, when a built several QRP radios and found a diode across the power leads to short out the power lines if they were connected in reverse, I immediately changed them to be in series with the positive line.

I will not present any new ideas to the group since it encourages thoughts that they are being dragged down, somehow, when at least it causes people to think about it, at least.

Arrivederci, colega.

KK5R

On Monday, August 10, 2020, 1:06:24 PM EDT, IZ4SJP Carlo <carlo@...> wrote:


Bob, did you try it?



Doug W
 

On Tue, Aug 11, 2020 at 05:27 PM, Bob Lunsford wrote:
I wish there were a way to have the comments relate back to the previous comment by a thread link or merely posting the previous comment with the posting comment as is done here.
If you are on the website, all you need to do is highlight part of the post you are replying to before clicking reply and it will show in your post as a quote like I have done here.
 
--
www.bitxmap.com


Bob Lunsford
 

I used "reply" to post this comment. Thanks for the advice, didn't know this could be done. But a "reply" with Firefox contains the whole/original comment.

Wish others would do this but since I'm a 'noobie' here, maybe others also do not know what you just told me. Thanks again.

Bob — KK5R

On Tuesday, August 11, 2020, 7:00:26 PM EDT, Doug W <dougwilner@...> wrote:


On Tue, Aug 11, 2020 at 05:27 PM, Bob Lunsford wrote:
I wish there were a way to have the comments relate back to the previous comment by a thread link or merely posting the previous comment with the posting comment as is done here.
If you are on the website, all you need to do is highlight part of the post you are replying to before clicking reply and it will show in your post as a quote like I have done here.
 
--
www.bitxmap.com


Mick
 

On Tue, Aug 11, 2020 at 07:00 PM, Doug W wrote:
If you are on the website, all you need to do is highlight part of the post you are replying to before clicking reply and it will show in your post as a quote like I have done here
Cool the highlight works, Thanks
 
--
 

73
Mick VA3EPM