[Kenwood] TS-830s IF Amp Alignment Question

Thu Jul 31 09:34:56 EDT 2008

> Page 37 of the TS-120 Service Manual has the level conversion chart. It's
> also in other Kenwood service manuals but not in the 830. I don't know why
>> Japanese "SG" American "SG" My Notes
> -6db .25uv
> 0db .5uv -113dBm
> 6db 1uv
> 12db 2uv
> 24db 8uv
> 30db 15.8uv
> 40db 50uv -73dBm

This chart is offset by one row under either column: 0 dB should be 1 uV,
-6 dB should be 0.5 uV, 40 dB should be 100 uV. I wrote down the correct
values in all my 120/130 manuals long ago.
One has to keep in mind that there is a difference, decibels-wise, between
doubling POWER, and doubling VOLTAGE: when you double VOLTAGE, the number
of dB increase is TWICE that as for power-doubling: that is, 6 dB. That's
why the formula is 20 * log of the ratio of the voltage increase. For
power, it's just 10 * the ratio of power increase (or decrease). 0 dBm is
1 milliwatt and 0 dBuV is 1 microvolt.
Steve, K0XP
> my TS-830s.
>>>> Service manual (third edition), page 36, step 15, "IF Amp Adjustment".
>> Calls for applying a 1.9MHz, 40dB signal from an RF signal generator and
> gradually decreasing the generator output to -6dB during adjustment.
>>>> My question: a 40dB signal decreasing to -6dB translates to what actual
> VOLTAGES?
>> My signal generator output is adjustable from 0. 1 microvolt to 3 volts
> (into 50 ohm load).
>> (I don't understand how to convert dB to microvolts).
>>>> Tnx, Bill, w0ng
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