[R-390] Two questions

[Scott, Barry (Clyde B)]

Oops.  It wasn't a keyer, but a TTL to RS232 converter.  I'm building a keyer and had it on my mind.  The question stays the same, though.

Barry(III) - N4BUQ

1.  Did all 390 models include the squelch.  It was an option on the 390A.

2.  I was looking at a schematic (a keyer) a couple of days ago and noticed there were two caps in parallel -- a 22mfd and a 4700pfd.  These feed a solid-state VR.  Why would it be necessary to have this arrangement?  When caps are in parallel, doesn't the circuit see this as simply the sum of both capacitances -- in this case 22.0047mfd.  It would seem the 4700pfd is insignificant with respect to the 22mfd cap and I can't see the need for it.  Any thoughts as to why this was done?

3.  Hammarlund.

Thanks,

Barry(III) - N4BUQ