I don't have any experience with Moxtek, and I don't know, what version of JFET structure they employ. Besides two well known structures, which we have mentioned here already (substrate, tetrode), there are other variations, employed in ICs by AD - TOPGATE JFET, and by TI and BB - Di-FET.
Some clues about Moxtek FETs properties can be taken from the noise specs: corner freq. of ~10KHz, and not extending below 1KHz. May be they are optimised for relatively high freq. of operation. There are plenty of other transistors with impressive specs, developed/optimised for higher freq., like AM band. You may compare to these examples:
Philips BF851/861
2SK291
2SK445
2SK508
2SK518
2SK709
2SK1961
All d/s are available.
Some clues about Moxtek FETs properties can be taken from the noise specs: corner freq. of ~10KHz, and not extending below 1KHz. May be they are optimised for relatively high freq. of operation. There are plenty of other transistors with impressive specs, developed/optimised for higher freq., like AM band. You may compare to these examples:
Philips BF851/861
2SK291
2SK445
2SK508
2SK518
2SK709
2SK1961
All d/s are available.
Well, Kenpeter, I found p-ch TO-72 mosfet and did this experiment myself.
Supply was -30V, going through CCS 2SK246GR (3.1mA) to the drain.
Parallel to drain/source was 22K pot, viper going to mgate.
Substrate was connected via 300 Ohm to another pot viper, dividing 1.5V battery voltage for Subs-Source.
One DC voltmeter - to the subs., another - to the drain.
Mgate viper was adjusted to bias Drain to -15VDC. Mgate was at -4.77V (high thresh. voltage, low transconductance mosfet, Drain current was 2.3mA, 35mW dissipation).
Changing Subs. voltage by 0.1V changed Drain voltage by 0.1V. Mu=1.
No use for this type of connections.
Supply was -30V, going through CCS 2SK246GR (3.1mA) to the drain.
Parallel to drain/source was 22K pot, viper going to mgate.
Substrate was connected via 300 Ohm to another pot viper, dividing 1.5V battery voltage for Subs-Source.
One DC voltmeter - to the subs., another - to the drain.
Mgate viper was adjusted to bias Drain to -15VDC. Mgate was at -4.77V (high thresh. voltage, low transconductance mosfet, Drain current was 2.3mA, 35mW dissipation).
Changing Subs. voltage by 0.1V changed Drain voltage by 0.1V. Mu=1.
No use for this type of connections.
Someone mentioned (Ex soviet) parts KP901, 904, 905, 913. As far as i can understand Russian, these are low Gm MOSFETs for VHF-UHF power amps. I coul;d be wrong as there really are no datasheets for these on the net, save for general parametric data. These are relatively low voltage (50-70V), 4-5A, with fairly low transconductance (usually below 1A/V). The data does suggest a SIT but the text mentions insulated gates...
Then there is the 2P/KP701A (A702A/A702B), rated 400V, 17A, 40W (HF case type) with a transconductance of about 1.5A/V. It is not entirely clear, as the Russioan parametric tables make no difference between MOS and JFET, but some series 700 FETs with very close numbers cross to European BUZ and USA IRF types, so it is more likely it is a MOSFET. There are other references on the net, also suggesting it's a MOSFET.
So... unless someone has relable data, it seem there are no Russian SITs around
Resurrecting a REALLY old thread here...
Indeed there were Russian SITs but at this time I am not sure there are any to be bought, although there are some indications one may still be in production for military purposes, which makes it unobtainium.
The relevand part numbers are KP801 (copy/derivation of the NEC 2SK70), KP802 (High voltage version with lower current), KP927 (Advanced SIT, 400V/16A). All are in TO3 cases. There are differences depending on suffix letters A,B,V,G, mostly maximum voltages and linearity.
I have been able to obtain a few KP802, although the parameter spread is high (as with most SITs), all in all it's a very linear device, especially at higher voltages (100-300V).
Indeed there were Russian SITs but at this time I am not sure there are any to be bought, although there are some indications one may still be in production for military purposes, which makes it unobtainium.
The relevand part numbers are KP801 (copy/derivation of the NEC 2SK70), KP802 (High voltage version with lower current), KP927 (Advanced SIT, 400V/16A). All are in TO3 cases. There are differences depending on suffix letters A,B,V,G, mostly maximum voltages and linearity.
I have been able to obtain a few KP802, although the parameter spread is high (as with most SITs), all in all it's a very linear device, especially at higher voltages (100-300V).
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