[Milsurplus] MO-1 / MAK Operating Precautions

[mac]

Hue,

Yes, I can see what they're taking about.  The modulation reactor is  
located in the power supply, so the modulated HV line runs through two  
connectors with very close pin spacing.  Also, there is no provision  
for disconnecting or disabling the modulator during tune up and the  
only way to key the transmitter is with the microphone PTT switch.   
Problem waiting to happen here.  In addition, no variable links or  
roller inductors in this rig, all loading adjustments made via tap  
switches so holding loaded plate current in a 5ma window is somewhat  
problematical.

Thanks for the info.

More to follow as I get deeper into this little beast.

Dennis D.  W7QHO
Glendale, CA

On Jun 27, 2009, at 12:35 AM, Hue Miller wrote:

> Service Notes Navships 900,000.1
>
> Operating Precautions for the MO-1 / MAK Equipments
>
> Due to the high modulation capabilities of the
> MO-1 / MAK equipments, it is essential to assure
> that the final amplifier is loaded at all times when
> modulation is applied. Otherwise dangerously high
> voltages can be generated which may damage the
> insulation or the connector plugs. To eliminate the
> possibility of such damage to the equipments, the
> following precautions should be strictly observed:
>
> 1) Preliminary tuning should be accomplished with
> an unmodulated carrier.
> 2) Completely resonate the antenna circuit and
> adjust coupling so as to load the final amplifier
> to 95 to 100 mA plate current.
> 3) Do not apply modulation under any circumstances
> unless there is a load of at least 95 mA on the
> final amplifier.
> 4) With the final amplifier loaded from 95 mA to
> 100 mA, 100 percent modulation is easily
> obtainable. If the plate current is allowed to
> drop below 95 mA, the transmitter can easily
> be overmodulated. If the plate current is more
> than 100 mA, the plate dissipation of the tube
> will be exceed; also the percentage of
> modulaton will be low. Therefore, care should
> be taken to maintain proper loading on the final
> at all times.
> 5) When using ICW, it is recommended that
> the feed-back resistor R-122 be adjusted so
> that the percentage of modulation be adjusted
> so that the percentage of modulation does not
> exceed 80 percent with the power amplifier
> loaded to 95 mA.
> 6) Never attempt to shift frequency with the
> key down, using ICW. Under these
> circumstances, the final amplifier is
> momentarily unloaded and the insulation
> can be damaged.
> Since there have been several failures of
> connector plugs in these equipments
> which are directly attributable to improper
> operation, strictest compliance with the
> above precautions is recommended. In
> this connection, it is suggested that a
> notice be posted near the equipment,
> reading as follows:
> WARNING
> With The Final Amplifier Loaded To Less
> Than 95 MA Plate Current
>
> [ sic! that last line is verbatim, but seems
> incomplete! Also, at the end of paragraph
> 5, there is an odd partial line:
>
> " as 9, the separation between turns in L-112
> and L-114"
>
> That's all there was! I wonder if this line belonged
> to this equipment or fell in from some other
> equipment's page???
>
> via: Hue Miller   re: couple of members running
> this equipment!
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