Scot
Big problem is if you have a division in the drive train ... depends
what mode you want to transmit , if you can select a shift x2 or
x4 the required , then you can drive down the divider train , which
in turn reduces the deviation to the required level by /2 or /4
harmonics are another way , bit messy , but say to tx wspr on 500 ,
take the first harmonic of the 'correct' 500 wspr drive , 1 MHz @ shift
x2 , > filter> then present this to the divide /2 driver chain , tx
is then 500 'correct'
Gary has used this to TX ROS and WSPR on 500 in the past via his class
D amp
There was / is a version on ROS MF that could be used to drive a DDS
, (although time expired , will run if the pc clock is retarded)
The ROS 8 KHz data mode has a class E/D setting, where the TX audio
drive is outputted at 16KHz , with x2 shift , to simplify the use
of a logic drive amplifier ..
Patrick of MULTIPSK , did code a special test version that produced
a x2 shift , that may be of use ,
It all depends which mode you want to transmit .......
However , something that may of passed un-noticed , Jim's design
for a EER transmitter uses a pair of complimentary output devices ,
thereby allowing the direct amplification of any mode , without a
divisional drive system to produce the 'complimentary' drive to the
final ...
G..
--------------------------------------------------
From: "Scott Tilley" <[email protected]>
Sent: Wednesday, April 20, 2011 9:32 PM
To: <[email protected]>
Subject: LF: MSK with a Class D transmitter...?
Hi All
I wonder if someone can explain to me how to feed an MSK signal into a
typical Class D transmitter?
I mean by typical that the TX has a 4013 type /2 system feeding two FET
drivers to drive FETs in a push-pull configuration.
If I understand correctly due to the fact MSK does not have amplitude
component to its signal that a non-linear transmitter can be used.
So, how do you do this with a Class-D TX as often used in LF/VLF?
Thanks,
Scott
VE7TIL
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