[Yaesu] FT-900 Modification for Variable "RF" Gain Control

[Dave Jordan]

Donald,

I'm going to make the RF gain mode today... it turns out to be another 10k
resistor R2334 (the sister to the R2335 -- noise blanker mode). Reducing the
resistance lowers the RF gain.  My plan is to run a wire to pin #6 of the CAT
connector.  That pin is not used.  I can then use a pot to set the RF gain to my

favorite level and then substitute the pot with a fixed resistor.  I presume the

same technique could be used with the noise blanker mode.

I too use the FT-900 for strickly mobiling.  In addition to the FT-900 noise
blanker I also use a JPS ANC-4 RF noise reduction system. The combination of the
both completely eliminates noise from my RV MSD Ultra-high voltage ignition
system. WIthout the ANC-4 the noise was about "S9" but with the ANC-4 the level
drops to "S1"...very quiet.  I'm now using 6.6K ohms for
R2335.

I use the upgraded SSB crystal filter from Yaesu.  It did clean up the skirts
noticeably...like the difference between running the noise blanker or not.

Yaesu has already gotten back to me on the question from last night. As soon
as I get the diagram I'll scan it in and be happy to make it available to anyone

who wants it.

HAVE FUN,
dave
WA3GIN


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