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S-Meter Calibration

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Doug Kingston

S-Meter Calibration

I have access to signal generator similar to this (
http://www.circuitspecialists.com/sdg830.html), but its minimum output is
4mv. The calibration calls for 50uV of signal.
It looks like I could set the output to 40mv (I don't like working at the
bottom of the range), and then attenuate the output with 3 20db
attenudators (e.g.
http://www.fairviewmicrowave.com/20db-fixed-attenuator-bnc-male-bnc-female-0.5-watts-sa01b-20-p.aspx)
in series which would reduce the voltage by a factor of 1000. Does this
sound like a viable plan?

-Doug-, KD7DK
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Don Wilhelm-4

Re: S-Meter Calibration

Doug,

That may work as long as the signal generator and the attenuators are
very well shielded.
If the brand name were Agilent (used to be HP), I would say that it
would be well shielded, but I don't know about a product from the "Siglent".

You may do better to invest in the Elecraft XG3. The calibration can be
automatic and painless when controlled by K3 Utility.

73
Don W3FPR

On 8/5/2015 6:41 PM, Doug Kingston wrote:

> I have access to signal generator similar to this (
> http://www.circuitspecialists.com/sdg830.html), but its minimum output is
> 4mv. The calibration calls for 50uV of signal.
> It looks like I could set the output to 40mv (I don't like working at the
> bottom of the range), and then attenuate the output with 3 20db
> attenudators (e.g.
> http://www.fairviewmicrowave.com/20db-fixed-attenuator-bnc-male-bnc-female-0.5-watts-sa01b-20-p.aspx)
> in series which would reduce the voltage by a factor of 1000. Does this
> sound like a viable plan?
>
> -Doug-, KD7DK
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Bob McGraw - K4TAX

Re: S-Meter Calibration

From my "chart on the wall", at 50 ohms, 4 mV is about -34.8 dBm and
50 uV is -73 dBm. Thus you will need an attenuator supplying some ~35
dB of loss.

From your numbers and starting at 40 mv {-14.8 dBm}, using 3
attenuators of 20 dB each will get "close". As someone else suggested
the XG3 would likely be a better choice.

73 Bob, K4TAX

On 8/5/2015 7:16 PM, Don Wilhelm wrote:

> Doug,
>
> That may work as long as the signal generator and the attenuators are
> very well shielded.
> If the brand name were Agilent (used to be HP), I would say that it
> would be well shielded, but I don't know about a product from the
> "Siglent".
>
> You may do better to invest in the Elecraft XG3. The calibration can
> be automatic and painless when controlled by K3 Utility.
>
> 73
> Don W3FPR
>
> On 8/5/2015 6:41 PM, Doug Kingston wrote:
>> I have access to signal generator similar to this (
>> http://www.circuitspecialists.com/sdg830.html), but its minimum
>> output is
>> 4mv. The calibration calls for 50uV of signal.
>> It looks like I could set the output to 40mv (I don't like working at
>> the
>> bottom of the range), and then attenuate the output with 3 20db
>> attenudators (e.g.
>> http://www.fairviewmicrowave.com/20db-fixed-attenuator-bnc-male-bnc-female-0.5-watts-sa01b-20-p.aspx)
>>
>> in series which would reduce the voltage by a factor of 1000. Does this
>> sound like a viable plan?
>>
>> -Doug-, KD7DK
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
>
>