ORIGINAL MESSAGE:
On Tue, 11 Dec 2012 08:43:00 +0000, G8TIC wrote:
>When you get your RF deck built its worth replacing the tube with a 2200
>carbon resistor to ground (to simulate RL) and using a VNA make sure
>your tuning/matching is in the right ball park before putting the tube
>in and applying volts ;-)
REPLY:
Wrong, especially on a high frequency like six meters.
The procedure should be done with the tube in place, but not powered
up. The 2200 ohm resistor does not "replace" the tube, it just
simulates what the tube's impedance will be when it is powered up.
Both tube and resistor should be in place, otherwise you're wasting
your time.
Incidentally, you don't need anything as fancy as a real VNA. A simple
MFJ SWR analyzer will do the job perfectly.
73, Bill W6WRT
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