[Amps] conversion scale from dbu to microvolts

[Martin Sole]

Hi Fern,

You need to be a little careful with some of the Japanese conversions 
'sometimes'.

Ok, 0dBuV (for most people these days) is 1uV p.d. or loaded or 
terminated or however you or your generator refer to it. In some cases 
though Japanese documentation uses 0dBuV = 1uV e.m.f. or open circuit or 
unloaded however you or your generator refer to it. Clearly the 
difference is 6dB !!!

Long years ago many people used the open circuit numbers, now with most 
things being 50 ohm the loaded numbers tend to dominate in which case

-7dBuV = 0.446uV p.d. or 0.892uV e.m.f

-13dBuv will be half the above (6dB difference) so 0.223uV p.d or 
0.446uV e.m.f

+20dBuV 10uV p.d or 20uV e.m.f

In all cases 0dBuV = 1uV, 6dB up or down doubles or halves it 
respectively. So if by chance they use the unloaded uV as a reference 
you need to reduce the above numbers accordingly.

73
Martin HS0ZED



Fern Rivard wrote:
> 
> 
>>    I just received the service manual for my Yaesu FT-1500M and would 
>> like to calibrate the S-Meter but unfortunately Yaesu uses dbu's which 
>> is all dutch to me as all of my test gear use either microvolts or 
>> dbm.
>>    It would be nice to find a conversion scale for this but Google did 
>> not bring up a chart for me.  For now, I need the conversion into 
>> either microvolts or dbm of:
>>
>> 1)   -7dbu
>>
>> 2) -13 dbu
>>
>> 3) + 20 dbu
>>
>>    Thanks from Fern
>>
>>
> 
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