[Elecraft] K2 and HW-101?
[email protected]
[email protected]
Wed Jan 16 13:23:01 2002
In a message dated Wed, 16 Jan 2002 11:25:29 AM Eastern Standard Time, Vic Rosenthal <[email protected]> writes:
> [email protected] wrote:
> > K2VCO said:
> > > Well, you could just use a 1-4 toroidal transformer
> > > between
> > > the input and a 200 ohm swamping resistor.
> > That might work, if the toroidal transformer can drive the capacitive load of
> > the tubes over the frequency range. Neutralizing would be disabled and a TR
> > system installed.
> You might have to add a small inductance to tune out the reactance the
> grid-cathode capacitance on 10 meters, which is effectively in parallel with the
> swamping resistor.
Where would you put the inductance?
> This is annoying, because we are trying to get away from
> input circuit bandswitching.
Why are we trying to do that?
As I recall the HW-101 circuit, the 80 meter coil in the 6146 grid circuit has a link on it that is used for receive antenna input. The other coils are switched in parallel to reduce the inductance. Why not just keep the grid coils and feed the RF in through that link via a suitable T pad (to absorb some of the K2's output and reduce impedance variation)
What I'm beginning to envision is this:
1)Get a basket case HW-100, HW-101 or SB series equivalent. Use a hacked-up hangar queen, not one that has a decent chance of ever working again. SB-400/401 might have possibilities, too.
2)Remove the meter, final amplifier and driver components ONLY. Sell the rest to keep other Heaths alive.
3)Transfer these to a nice new chassis (could be a couple of pieces of sheet metal held together by genuine Elecraft 2D connecters and panhead screws, or 6-32 sized shameless copies if you have machine tool capabilities). Original final cage and meter are reused, too. New front panel with nice knobs and meter(s). Eliminate the troublesome "rubber band" drive and the concentric plate/load nonsense of the HW series and have a nice clean front panel. Tune, Load, Band, Meter, Mode, Power.
4)Design TR system to match K2 and bias system for various modes. One possibility is to use the 160m/2nd RX adapter so that all the amp has to do is switch between amp output and 2nd ant input.
5)Power supply can be HP-23 if you have one or homebrew if you don't.
Waddya think, sirs?
--
An even stranger version:
Get a torn up Johnson Viking 2 and use just the final. Will work 160 thru 10 and the WARC bands. They are well shielded, rugged and easy to work on, but real desk-crushers. BA purists will recoil in horror at the idea, anyway.
--
It's legal for us hams to do this as a homebrew project for our own use, but not legal for Elecraft or any other company to
do it, either as a kit or an assembled unit. Something
wrong there.
73 de Jim, N2EY