THE GI7b COAXIAL-PULSE-TRIODE
Lo Stadio RF con 2 x GI7b sul mio amplificatore per i 50Mhz....... 700w con 15w di ingresso.....
| GI7b data | min | nominal | max |
| Heater | 12V | 12.6V | 13.2V |
| Heater | 1.8A | 1.92A | 2A |
| Plate voltage | - | 1500V | 2500V |
| Plate Current | - | 400mA | 600mA |
| Plate dissipation | - | - | 350W |
| Working freq | 2.7GHz | ||
| 20 mA/V | 23mA/V | 26mA/V | |
| Pout | - | 250W | |
| P in | - | 10W | 20W |
| C g-k | 10pF | 11.1pF | 12.2pF |
| C a-k | 0.055pF | 0.075pF | 0.08pF |
| C g-a | 4pF | 4.6pF | 5.2pF |
| Grid bias | -15 to -17V |
With its 350 Watts plate dissipation this tube is
a good choice for producing medium power (300 to 500 Watts). At a plate
potential of 2000 Volts the gain is around 13 dB and the efficiency about
60% on 144MHz when build in grounded grid. A 432 MHz version with a
half wave-line will give an efficiency of about 50% when build in built in
grounded-grid style.
The GI7b (LD7) is also good on 23cm. In
grounded-grid style with 3/4-wave coaxial-tank, at a plate potential of
1500V and Ia= 300...350mA. The pwr gain is still around 12...13 dB or
more. The efficiency is same as with 70cm configuration or around 50%.
With a good matching in the cathode circuit only 10...15W of drive is
needed.
(by Tom/ES2RJ).
Equivalent types :
The tubes GI6b, GI7b, GI7bt, GI70b and GI70bt are all the same
GI7b (=LD7). GI7b and GI7bt are completed by factory with plate radiators
(HgAl) and the others (#70) without (normaly used in water cooling items).