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Registered Member #54724
Joined: Mon Mar 30 2015, 01:12AM
Location: Livermore, CA
Posts: 7
Hi:
I have some tubes that I think may be better to sell off and use the money to buy other tubes more suited to VTTC use:
2 of VT-4-C / 211 6 of VT-101 / 837 1 of 830B
I heard that I should sell off the 211 tubes and get a 833 instead. I'd like additional tube recommendations considering the following:
I wish to make a small VTTC, running from a plate supply of about 400V / 0.1A to about 1000V / 0.2A. I'd like to start with the smallest VTTC / lowest voltage levels first.
Recently I've obtained a bunch of TV Horizontal Output tubes, ranging from small (6BQ6GTB: 6kV, 11W) to the largest (6LF6/6LX6: 8kV, 40W). I think that these should be good for small VTTCs running at lower voltages since they are relatively lower impedance tubes vs. many RF amp. tubes, and so may be better for VTTC operating at lower input voltages.
Registered Member #561
Joined: Sat Mar 03 2007, 02:46AM
Location: Adelaide Australia
Posts: 230
If you're using an 833A (I'm building one right now, actually) or 833C you would use a MOT with a voltage doubler to get 4kV in very short runs of 1kW or so.
11W and 40w is absolutely miniscule and you won't get very much performance from either. 400v to 1kV is also on the very low side for VTTC voltage though I can't think of a reason why it shouldn't work - though I'm no expert in the field.
You can pick up a Soviet clone of the 833A called the GU-48 for about US$100-120 on eBay.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Any transmitting/oscillator tube with adequate plate dissipation rating will work in a VTTC, just the right grid voltages and currents need to be selected (and sometimes additional grid supplies are needed, but this can be worked around with a cleverly tapped grid coil). The list is just too long, there are literally hundreds of usable tubes. Just from the top of my head / lyin around (mostly Russian/European tubes): GU81M, TB5/2500, TB4/1250 (any other TBx/xxxx tube from Philips), SRS360, SRS457, T380-1, RD200B, GU5B, GU39B, GU43B, GU47B, GU56, GU46, GU48, 304TL (a great tube, can supply large cathode currents) and finally the GMI-2B (more of an artifact - one of the largest glass tubes, pulse modulator beam tetrode rated at 32kVdc/110A peak current).
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Tubes to sell off for better VTTC ones
