About CountyComm GP-5/SSB dBu and S/N ratio

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billcox5

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Hello,

The manual doesn't explain in detail what these are and how to understand these numbers in relation to when listening to a station.

For example, which is more important, the dBu number or the S/N number when tuning a station? Is a high or low number in the dBu or S/N good or bad?

Can anyone explain to me in layman's terms about the numbers in the dBu and S/N column? Thanks
 

billcox5

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Hello radio fans,

I found this youtube video showing the countycomm gp-5/ssb. Perhaps a video is worth a thousand words. On the top display there are two columns of dBu and dB. What are these numbers below them telling me about signal? For example, is it good or bad? Do I need to do or adjust something based on the numbers in the dBu and/or dB columns?

I appreciate any help or comments. Thanks

https://www.youtube.com/watch?v=iUEGbKy8e3Y
 

majoco

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There is nothing you can do to 'adjust' the dBu or S/N - dBu is a measure of the strength of the received signal in units of "decibels above 1 microvolt" and S/N is the ratio of "audio signal to noise ratio" again in decibels.

30dBu is a big signal and as you can hear, it sounds pretty good. The S/N ratio is pretty meaningless as your Mk1 ear will actually tell you how good it sounds! The "dBu" may be handy as a measure of how good a different antenna is or as a bit of test gear to test a signal generator.
 

billcox5

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There is nothing you can do to 'adjust' the dBu or S/N - dBu is a measure of the strength of the received signal in units of "decibels above 1 microvolt" and S/N is the ratio of "audio signal to noise ratio" again in decibels.

30dBu is a big signal and as you can hear, it sounds pretty good. The S/N ratio is pretty meaningless as your Mk1 ear will actually tell you how good it sounds! The "dBu" may be handy as a measure of how good a different antenna is or as a bit of test gear to test a signal generator.
Hello majoco and thank you for the reply.

While I was waiting for a reply I was googling around about these two columns of dBu and S/N.

I came across this website S-meter and signal strength

Just to be sure I understand this. I will use the 30dBu as an example.

Is a 30dBu on the GP5/SSB equivalent to S4 or S9+30 on a receiver with a S meter? The chart on the sites shows S4 equals -30db and S9+30 equals 30db.

If you or anyone knows the answer It would be greatly appreciated.

Thanks again :)
 

majoco

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Ah, then you need my magic chart that I drew up many moons ago - you can see the date in the corner.....

Just read across from one scale to another .....

So you can see that +30dBuV is between S7 and S8. Just don't put too much faith in the "S" meter readings - there is no real standard but most manufacturers now agree on 100uV for S9.
 
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billcox5

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Ah, then you need my magic chart that I drew up many moons ago - you can see the date in the corner.....

Just read across from one scale to another .....

So you can see that +30dBuV is between S7 and S8. Just don't put too much faith in the "S" meter readings - there is no real standard but most manufacturers now agree on 100uV for S9.
Thank you majoco for the clarification. I have a better understanding now. God bless and have a happy 2017 year :)
 
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