The symptoms below are consistent with the tube working into too low a load impedance (loaded too heavily) and not developing enough Voltage swing on the tube's plate. Loading comes from reducing the
Let's cover four kind of interference * Radiated emission from the amplifier o High E or B fields inducing currents on the PIC board * Conducted emissions from the amplifier o Signals entering the PI
Absolutely. In fact, the PIC probably doesn't really like 3 KV on it's A/D inputs. ;-) The usual approach calls for a 1000:1 resistive divider that puts out a voltage of about 1 Volt for each KV (dep
Out of curiosity, how does a zero crossing solid state relay work? I had thought it had a triac inside, but your comment about voltage drop makes me question that assumption. jeff, wa1hco ___________
Scott... I learned a lot about practical RF network design from using a computerized Smith chart program. Those programs let you play around with values and explore results in seconds. You don't need
Dan... The input impedance of a transistor at RF frequencies runs a few ohms, depending on a variety of factors, with high power meaning lower impedance. 30 dB in power means 1000:1 in power or about
Paul... Since the H bridge generate a square wave voltage on the primary and not a sine wave, the output should also have a square ave stepped up by the turns ratio. The 1.4X or 0.9X rules apply to s
I think the statement about grid impedance is true because it refers to a principle of _tube_ operation. The grid does indeed have a high impedance with _respect_ to the cathode without grid current.
Plate output capacitance doesn't matter too much because it gets absorbed into the plate output network. The biggest consequence becomes the high Q and high circulating currents that naturally occurs
If that line of reasoning were true, then we would be required to never talk softly when transmitting. It seems obvious that once tuned for 1500 watts, any output less than that will result in lower
As a former 75 AM'er, it's, "yea-yea-yeayaaaaaaaaaallo" jeff, wa1hco _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo
Steve... A different inductance will only change the Q of the tank, not the match, assuming you tune and load the amp properly. Making the inductor smaller will require more tune capacitance to reson
When I play with this design, it appears that 5 uH for the inductor at 3.8M is just too low. Rp 1000 Cstrays 20 p Ctune 410 pF L 5 uH Cload 1660 pF Those values seem to agree with what you described.
When i responded to your original email, I ignored the in/out more/less capacitance because you said that you could get 1.5 kW out. That means you can get a match. That email didn't make it to the li
If you want a Q of 12, values of about 430pf, 4.6 uH, 1900 pF do work. But you really only need a Q of about 7 to comfortably match 1000 Ohms to 50 Ohms. The Q of 12 rule was created in the days of h
Roger... The best place for design examples of 2 meter amplifiers is http://www.nd2x.net/base-1.html It's aimed at amps using the Russian tubes but the designs work with any tube having a similar siz
This might be getting off topic, but how does one "hiss a cow"? ...something about vacuum perhaps? jeff, wa1hco _______________________________________________ Amps mailing list Amps@contesting.com h
Gary... You will see only 10 dB gain at 2500V...so about 1000W out for 100W in. Plate current can swing to 1A, but you may not be able to get it much above 800 mA. Grid current can get very high comp
Superb kits do exist... - Cheaper than commercial (by _far_) - Better performance - More advanced technically than a rice box - Significant learning experience - Compatible with entry level or kids h
What do people think of the amplifier by Bill W4NFR shown in the latest QEX? It uses an LDG tuner on the amplifier input instead of a set of filter/matching networks for each band. It seems like an i