I recently acquired a slightly used 8410 (mfg 3/2014). I was surprised to learn it had 4CX1500B tubes rather than the 4CX1000A's. Looking at the RF Concepts website for tubes I notice the price is lo
The first thing that comes to my mind is, the grid dissipation is 0W (4CX1000A), and the plate dissipation is lower than a 4CX1500B. I'm not sure about the o/p being lower in the 4CX1500B; should be
Hi Peter, I believe the drive on the 1500B is lower than the 1000A. Here is a deal for you. I have two never used 4CX1500B Eimac tubes never been in a socket for that matter. I'll sell the for $420.0
I believe the difference between the 1w grid dissipation rating of the 1500 and the 0w of the 1000 isn't significant and may only be a matter of how the engineers decided to present it on the data sh
To all tube specialists out there, I wonder whether the 4CX1500B is _intrinsically_ a low distortion tube, by any special construction techniques, or if the good IMD rating comes simply from the oper
This last contest weekend I was at the CE6TC contest site. It was a two station setup, one equipped with an Alpha 89, the other with a Ten Tec. Both amps worked great, but the streams of hot air blo
Welcome to tetrodes Manfred. Very few are designed for very low IMD and excessive, IMO, idle current is a way to appease the masses in the ham world. The 600W dissipation Russian GU-74B was fraudulen
Funny, most TV transmitters in Europe with combined sound and vision amplification have been with tetrodes in their final because of their high linearity. I never saw a commercial communication HF am
Indeed Peter. And high plate bias current and associated low efficiency is part and parcel of achieving high linearity and low intermod from AB1 tetrodes. Low plate idle current and low IMD are mutua
And in North America the emphasis has been on both types as both have their uses in broadcasting and in communications where the latter mostly use grid driven with low power driver stages and large s
Welcome to tetrodes Manfred. Very few are designed for very low IMD and excessive, IMO, idle current is a way to appease the masses in the ham world. The 600W dissipation Russian GU-74B was fraudulen
If you look at the characteristic curves on the datasheet, you can see that it is a different tube. I wonder whether the 4CX1500B is _intrinsically_ a low distortion tube, by any special construction
Indeed Peter. And high plate bias current and associated low efficiency is part and parcel of achieving high linearity and low intermod from AB1 tetrodes. Low plate idle current and low IMD are mutua
One nice thing about home brewing a grid driven tetrode amp with the GU74B is that you don't need a tuned input, just a 50 Ohm resistor. With 2 tubes, 50-60W drive gives you 1500W out. With suitable
Don't be concerned over idling current in tetrodes. As long as you can cool the tube, let it conduct to whatever it takes for IMD. I've made amplifiers from ~3 to 200 MHz, for 30 years now, as work r
Yes Jim, the maximum impact bang of course comes from PTT operation... Leigh VK5KLT Indeed Peter. And high plate bias current and associated low efficiency is part and parcel of achieving high linear
Quoting John Lyles <jtml@losalamos.com>: Enjoy building amplifiers and don't make it a pain for yourself or your peers. 73 John K5PRO Good post John, Sounds like you had the perfect job for a ham rad
I don't remember the tube designations any more as it's been 30 plus years since I worked on them, but we ran 200 - 250 KW as an oscillator, induction heater. They were heavy (compared to an 8877, 4C