[AMRadio] Source Broadcast Xmtrs

[Ron Youvan]

Hi  Ed Sieb:

> I can tell you categorically that the FT-990  is very poor on AM.   For one thing, the ALC
> cannot be  removed, leading to compression and  backwards modulation on audio peaks.   The
> proper way to run a rice-box on  AM is to lift the ALC, so as to allow good positive
> peaks.  As well, the '990, unless modified, has  poor audio bandwidth on AM.

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   A Stradivarius is only of value to a master violinist.
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Operating manual for FT-990 - page 33.

AM transmission
   Transmitter power output in the AM mode is
limited to 25 Watts (carrier).  All you need to do is
to adjust the MIC control to avoid overmodulating,
and select the desired power level.

[] With the AM mode selected, set the meter selector
    to the PO position, and preset the RF PWR control
    fully clockwise.

[] Even if you have already set the MIC control as
    described for SSB transmission, you will need to
    readjust it to avoid overmodulation.

[] VOX operation can be used in the AM mode,
    but for now,  make sure the VOX switch is off, so
    as not to confuse adjustments.

[] Close the PTT switch and speak in to the micro-
    phone while adjusting the MIC control to the
    point where slight movement of the (PO)
    meter can be seen.  Don't set it too far beyond
    this point or your signal will be distorted.

[] Adjust the RF PWR control for the desired output.

     The speech processor is disabled in AM mode.
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   The FT-990 has a good reputation for good AM quality.
-- 
    Ron  KA4INM - You can't fool me ...
                       ... I'm a moron.