Date: Thu, 31 Mar 2011 17:25:42 -0700 (PDT)
From: Bill Smith <ko4nrbs@yahoo.com>
Subject: [Amps] PI Calculation using G3SEK Excel Spreadsheet
Are these values correct (in ??) for two 3-400Z tubes at 2500vdc and 800ma
Plate Current?
There is so much information there I get lost.
Input Supply voltage E 2500 V
Input Max DC anode current Ia 0.8
Input K factor K 1.6
Input RF power output W 1500 W ??
Info Estimated RL based on E, I and K 1953 ohms??
Input Efficiency e 56 %??
Info Estimated RL based on E, W, e and K 1458 ohms??
Input Enter your choice of load resistance to be used for the calculations. RL
1900 ohms??
Input 2: Antenna load resistance R2 50 ohms??
Input 3: Operating frequency F 7.2 MHz
Input 4: Overall network Q Q0 12
5: Strays compensation
Input Output capacitance of tube(s) Cag 10 pF??
Input Strays local to tube Cs1 5 pF
Cout = Cag + Cs1 Cout 15
Info Total effective parallel capacitance of tube, strays, RFC etc Cp 25.0 pF??
73,
Bill Smith KO4NR
### I have been using the GM3SEK pi/pi-l software for years now....and
it's always DEAD ON. It has been
used on several RF deck designs, from small tubes, to the yc-156 variety.
160-6 m too.
## It factor's in stuff that everybody else's doesn't. That stray uh.....
between anode and PI net makes a huge difference !
This is exactly how we get the bigger tubes to play on 10m. You will see,
that by adding just a tiny bit of stay L...like .5 uh
between anode and input to pi-net.......that ur plate load Z will be
transformed to a much lower value.
## You can then juggle the values of this stray L..... and the uh of trhe main
10m coil.... and also the loaded Q... and you will that
you can get almost any tube to work on the higher bands. You will also see
the effect it has on the next lower bands.
## Nobody elses pi pi-l software appears to factor in stray Uh and stray
pf. all those strays can easily be measured with a lcr meter..
including cabinet side walls and top lids etc,
Ian's software can't be beat...superb.
Later.......... Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|