Very interesting.
What IMD values would you consider "bad". "ok" and "excellent"? As
examples, QST July '03 rates the ICOM 703 transmit 3rd order IMD at 24
db below PEP when running 10 watts. The March '06 QST shows the YAESU
FTDX9000 3rd order IMD at 35 db below PEP when running 200 watts.
24 db below 10 watts is 40 mW +/-, a small but still respectable qrp
signal that's rf "junk".
24 db below 200 watts would be 1 watt +/- !
Is there an FCC mandated 3rd order IMD requirement?
Inquiring minds (at least mine) want to know ;-)
73,
Lenny W2BVH
Charles Greene wrote:
Darwin,
I have a linear that has about 1000 watts output when driven with
approx. 60 watts in class AB2 for CW and a little more when operating
class AB1 for SSB. It's an old Hallicrafter HT33A with a PL172
pentode amplifier tube. I tried it using my K2/100 on PSK31 with 20
watts average power from the K2/100. The amp put out 400 watts ave
power. The IMD coming out of the amp was identical to the IMD of the
K2/100 without the amp, indicating no more distortion was added by the
amp. I don't expect you to hunt for a HT33A, but the principles are
the same. The efficiency is lower because of the idling power, but
since it is all coming out of the power line, who cares?
73, Chas W1CG
At 11:13 AM 3/8/2006, Darwin, Keith wrote:
Since a linear amp is supposed to be "linear", is there any reason that
you have to run 65 to 100 watts into one? What if you used a linear
designed for 65 watt drive and only gave it 15 watts? Does the spectral
purity change? Does the efficiency drop? Does the linearity degrade?
- Keith KD1E -
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
