Does this Hellp ? Re: [Yaesu] FT-1000(X) S-meter calibration

[Tyler Stewart]

I recently realigned one of my MP's and found the S meter to be right on the
money as found....I used a calibrated signal generator in a Motorola service
monitor.

..and it agreed with the figures you quote from the manual.

Since 100dbu = S9 + 60db, I assume that S9 has to be +40 dbu.  Using the given
0dbu = 0.5 uV from the manual, you can come up with the 40dbu= 50uV

73, Ty K3MM

-----Original Message-----
From: WD8ARZ <wd8arz@null.net>
To: yaesu@contesting.com <yaesu@contesting.com>
Cc: peca@galeb.etf.bg.ac.yu <peca@galeb.etf.bg.ac.yu>
Date: Tuesday, November 11, 1997 16:04
Subject: Does this Hellp ? Re: [Yaesu] FT-1000(X) S-meter calibration


>After reviewing the FT1000MP Service manual, I can provide the following
>information about what Yaesu calibration procedure directs.
>
>On page 3-1 in a note it says: Signal levels in dB referred to in alignment
>are based on 0 dBu=0.5uv.
>
>On page 3-8 it says for S-meter full scale: Connect the RF signal generator
>to the antenna jack, and inject a +100dBu signal. Tune for peak indication
>on the S-meter. Adjust VR2002 for S9+60dB on the S-meter.
>
>There are earlier steps for setting the S-meter segments to just being off,
>and just being full scale for minimum and maximum settings of the rf gain
>control. Rf and if stages have also been calibrated prior to the S-meter.
>
>If this information is valid (main manual is dated august of 95, but I am
>sure some updates have occured on some of the pages), then unless I am
>missing something, full scale is 100dB for +60dB over S9.
>
>With just a 40 foot peice of wire, I have seen +60dB over S9 on some
>shortware stations. Such as on 5.070 Mhz out of Nashville Tn. If a FT1000MP
>is always reading too low on the S-meter, and there is not a rig problem,
>then it needs to be calabrated. Also note that some of the calibration for
>this radio is part of the hidden 9-x menu options. Making changes to those
>settings will affect calibration and must be done correctly with elaborate
>calibrated test equipment.
>
>Band noise on 80 meters most nights routinely hold the s-meter over S9. If
>anything on my rig, I find the receivers to be hot and quite often have the
>IPO off and a attenuater value switched in. (this improves audio quality on
>strong signals and the signal to noise ratio)
>
>Hope this helps.
>
>73 from Bill Stamps - WD8ARZ
>E-Mail Reply to:
>wd8arz@null.net
>
>----------
>> From: peca@galeb.etf.bg.ac.yu
>> To: yaesu@contesting.com; 1000mp-list@jehosophat.com
>> Subject: Re: [Yaesu] FT-1000(X) S-meter calibration
>> Date: Monday, November 10, 1997 10:21 AM
>>
>> Tyler Stewart wrote:
>> >
>> > The MP is full scale at S9 + 60 DB, which Yaesu sets for +100dbu.
>> > That would make S9 a +40dbu, which tranlates to 50 microvolts
>> > on a 50 ohm sig. gen.
>> >
>>
>> Could someone please explain this ????
>> It is my job to know things about dBu, dBm, uV, etc, but this conversion
>> is totally unclear to me!
>>
>> Isn't it dBu = 20log(U/1uV) ?
>> where:
>> U is expressed in volts,
>> 1uV is what it looks like it is:) and
>> 'log' is a base ten logarythm.
>>
>> So, 50uV/1uV = 50 -> 20log(50) = 33.979dBuV
>> And +40dBuV would be:   10^(40dBuV/20)*(1uV) = 10^2 = 100uV
>> If you write it down on paper it's much more clear.
>> And for power it's dBmW = 10log(P/1mW)
>>
>> Hmm...unless you mean dBuW when you say dBu ? (which almost sure doesn't
>> fit into my definition, too :)
>>
>> 73 de YT1ZKB
>> zoran
>> kn04ft
>
>
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