[Johnson] A question from A New BA operator.

Thu, 21 Mar 2002 13:27:13 -0500

Yes, this has been cleared up. I forgot the KWS-1 was running AB-1 and
the Valiant C. Very simple if I'd stopped to think about it before
responding.

Yes, I do know the difference between the grid bias control on the KWS-1
PS deck and the drive (carrier level) ocntrol on the KWS-1 RF deck.

73, Ray  W2EC

[email protected] wrote:
> 
> Ray & all:
> KWS-1 manual Section 3.2.3
> a. Tune the transmitter exactly as for cw ....
> b. Switch to AM operation
> c. Back off the CARRIER LEVEL control until power drops 1/4 the cw value
> (1/2 antenna current). This corresponds to a plate current of about 275
> ma.
> 
> NOTE: Section 3.1 c. Turn the PA PLATE voltage on. Advance PA grid bias
> control until PA idling current is 100 ma.
> 
> The PA grid bias control and the front panel carrier level control are
> two different things. Review Section III "Operation" in the manual.
> 
> Pete
> 
> On Thu, 21 Mar 2002 11:33:07 -0500 "Ray, W2EC" <[email protected]>
> writes:
> > That's interesting. As I said, I hadn't tried it on the Valiant. I
> > mentioned it only because that is the method indicated by Collins to
> > run
> > the KWS-1. According to the Collins manual, you load the KWS-1 (pair
> > of
> > 4X250B's) to full output, then reduce the grid drive (watching the
> > plate
> > meter and a power output meter) until you get to a power output
> > level
> > you want. For example, I load the KWS-1 to 500ma which gives about
> > 575
> > watts CW out. Then I reduce the grid drive to a plate reading of
> > about
> > 275ma, which gives about 140 watts CW out. This is the exact
> > procedure
> > as depcited in the Collins Manual for reducing power and is how I
> > run AM
> > with the KWS-1.
> >
> > Without thought or investigation I just took it that dropping the
> > grid
> > drive a bit in the Valiant would provide the same power reduction.
> > What
> > would be the different forces at play that would make it OK to do it
> > on
> > the KWS-1 but not on the Valiant?
> >
> > 73, Ray  W2EC
> >
> > [email protected] wrote:
> > >
> > > Always run the 6146's at their rated grid drive voltage. Loading
> > up the
> > > Valiant to full power and then using the grid drive control to
> > reduce
> > > power is wrong. It will cause AM distortion and drastically reduce
> > the
> > > life of the tubes. If you want to reduce output power, put a 3, 6,
> > 8, or
> > > 10db pad between the transmitter output and your antenna. A less
> > > attractive way, and not normally recommended, would be to put a
> > variable
> > > pot for the screen resister of the driver tube. Always run the
> > output
> > > tubes at their rated grid voltage.
> > > Pete,WA2CWA
> > >
> > > On Thu, 21 Mar 2002 09:12:55 -0500 "Ray, W2EC"
> > <[email protected]>
> > > writes:
> > > )........
> > > >
> > > > Another thought, and I haven't tried this, is to load the
> > Valiant up
> > > > to
> > > > full power (330ma for AM, 450ma for CW), peak the grid then back
> > off
> > > > the
> > > > grid drive (normally 8ma) until you get the power level you
> > want.
> > > >
> > > > 73, Ray  W2EC
> > > >
> > > > "Guy Olinger, K2AV" wrote:
> > > > >
> > > > > Correct. Run it at specs.
> > > > >
> > > > > The plate voltage is fixed, the screen voltage is fixed, the
> > L/C
> > > > > ratio's in the tank circuit are only partly variable since the
> > L
> > > > being
> > > > > used on a given band is fixed. The whole shebang is at
> > maximum
> > > > > efficiency at the specified settings.
> > > > >
> > > > > I've seen guys operate a Valiant AM until the cows came home.
> > > > Just
> > > > > don't drop a book on the mike switch and get up and leave.
> > When
> > > > your
> > > > > voice starts to hurt let the other guy transmit :>)
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Dr. Clifford L. Coleman" <[email protected]>
> > > > > To: <[email protected]>
> > > > > Sent: Wednesday, March 20, 2002 4:23 PM
> > > > > Subject: Re: [Johnson] A question from A New BA operator.
> > > > >
> > > > > > While restoring my valiant, I found(as the manual suggests
> > )
> > > > that
> > > > > less
> > > > > > loaded causes high modulator current-so I tune it up to
> > full
> > > > power.
> > > > > cliff
> > > > > > k9jts
> > > > > > ----- Original Message -----
> > > > > > From: "Mullin, Edward J." <[email protected]>
> > > > > > To: <[email protected]>
> > > > > > Sent: Wednesday, March 20, 2002 1:40 PM
> > > > > > Subject: [Johnson] A question from A New BA operator.
> > > > > >
> > > > > >
> > > > > > > Hello All,
> > > > > > >
> > > > > > > I've been lurking on this mail list for a while, as I've
> > been
> > > > > > > working on my Valiant.  So far I have gotten it working
> > > > again,
> > > > > (recapping
> > > > > > > and replacing a couple of tubes was all it needed:)   Now
> > I
> > > > want
> > > > > to use it
> > > > > > > on the air.  (I've been testing into a dummy load during
> > > > > restoration). I'm
> > > > > > > new to BA's (and Ham operations) in general, and  I've
> > been
> > > > > reading the
> > > > > > > manuals alot.  What I want to know is: What is the
> > correct
> > > > method
> > > > > for
> > > > > > > transmitting at less than full power. The manual is good
> > at
> > > > > describing the
> > > > > > > tuning process, but it doesn't really cover this
> > > > information.(at
> > > > > least I
> > > > > > > didn't figure out where it was.)
> > > > > > >
> > > > > > >
> > > > > > > 73 de KB1HYS
> > > > > > >
> > > > > > >
> > > > > > > > Edward Mullin
> > > > > > > >
> > > > > > > >
> > > > > > > _______________________________________________
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> > > > > >
> > > > > >
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> > > > >
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> > > >
> > >
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> 
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