[Elecraft] K3: 630m amplifiers

[Edward R Cole]

Jim,

I was thinking of back in the 1950's when class-C was used with 
amplifiers for CW.  I guess the finals were direct-keyed and not 
driven by a keyed stage.  Its been awhile.  My DX-35 used grid-block 
keying and ran screen-grid AM on the 6146. But then you youngsters 
probably don't go that far back so would not know this.  Just yanking 
your chain a little, Jim, so don't get all riled up by that statement 
(you and I both were licensed in the 50's; ex-K8MWA).

I was thinking that my classic W6PO-8877 was running class-C but in 
fact is running linear (probably class-AB).  Class-C was used in the 
past for higher efficiency when gain was expensive.  Now even on 
microwaves gain is cheap.

But you missed the point that I am not planning to build a class-C 
amp for 630m: "I think its just
simpler to provide class-AB then its a non-issue"; a direct quote of 
what I said.

If you look at my original post on this topic:  "I am wondering what 
kind of interest there would be for a linear amp that could be driven 
by the K3s/K3?"  No where did I suggest anyone use a class-C 
amp.  Other's brought up using class-C, D, E.

On 630m spectrum is dear so clean signals are more important than 
other bands.  Likewise, frequency stability is also required to be a 
good citizen on the band.  The ARRL Group specifies 1-Hz for both 
accuracy and stability.  The K3 with TCXO-3 (1ppm) can do that.

I don't have a P3.  Guess I would have to use my old frumpy HP141T.

73, Ed - KL7UW
Jim, nice pics on your QRZ.com

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On Mon,7/27/2015 10:43 AM, Edward R Cole wrote:
 > CW, JT65, FSK all do fine with class-C, of course.

Ed,

I suggest that you drive a Class C amp with a K3 transmitting CW and
look at the spectra with a P3 both at the output of the rig and at the
output of the amp. Set the P3 display for 5 kHz.

73, Jim K9YC

73, Ed - KL7UW
http://www.kl7uw.com
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