WB4VLQ
ELECRAFT K2 STUFF:
The K2 knob revealed:
I recently was given an extra K2 knob (courtesy of Rich KB2CPE / K2 #1102) to experiment with. There are several jpeg pictures of the knob in it's disassembled state listed below. In order to soften the edges of the knob (which I found somewhat sharp for my taste) the knob was turned on a lathe to remove a portion of the face. As it turned out, the metal center portion of the knob was very thin (50 mils?) and quickly came off during the turning operation. While I thought this was a disaster, what appeared below the metal face was quite interesting. It turns out that the knob has a groove that runs around the outer edge of the face, a groove that looks much like an o-ring groove. I have access to a large collection of o-rings at work and it turns out that a standard 025 o-ring fits perfectly in the groove around the knob face. This gives a softer feel at the knob edge and a better grip for fast tuning. The groove is just the right depth so that it tightly grips the o-ring but leaves the o-ring higher than the rest of the knob face. Since the metal faced was glued in place, the glue left some small bubbles and distortion in the knob's plastic face. This was carefully wet sanded away with fine grit sandpaper. I much prefer the plastic face as it doesn't show finger wear as prominently as the old metal face. Note that it is very easy to remove the brass weight in the knob by running hot water over it. This seems to quickly heat the plastic (but not the large thermal mass of the brass) so that the brass insert can be easily removed.
The brass insert back (note side hole to counter balance the set screws)
The knob inside view (with brass insert out)
The knob face (with o-ring not fully seated)
The knob face (with o-ring)
Elecraft K2 Parts data sheets:
As a service to other Elecraft K2 builders, owners and users, this site contains PDF format data sheets for most of the major components of the K2. In the future I hope to better organize things, but for now I just wanted to make this info available. I will be adding more of the transistors and other devices as time allows.
Front Panel Board:
U1 - Philips Semi, PCF8566 Universal LCD driver for low multiplex rates
U2 - Fairchild, 74HC165 Parallel-in/serial-out 8-bit shift register
U3,U4 - Texas Instruments, TPIC6B595 serial in to 8-bit out shift register
Z1 - C U I Stack, Inc., EC202C025A-2TP Panel/PCB mount rotary shaft encoder
Q1,Q2 - On-Semi, PN2222A general purpose npn transistor
D4-D6 - On-Semi, 1N5817 schottky diode, 1A, 20V
DS2 - Green LED array
Control Board:
U1 - Philips Semi, SA612 (SA602, NE602) Gilbert cell double-balanced mixer IC
U2 - National Semi, LM833N Dual audio op amp
U3 - National Semi, LMC6482 CMOS dual rail-to-rail in/out op amp
U4 - National, LM2930T-8
U5 - 7805T (78M05) 5V linear regulator
U6 - Microchip, PIC16C77-04/SP 40-pin, 8-bit CMOS microcontroller with A/D converter
U7 - Microchip, 25LC320 32K SPI bus serial EEPROM
U8 - Maxim, MAX534 +5V low-power 8-bit quad DAC (rail-to-rail output buffers)
U9 - National Semi, LM380N-8 Audio amplifier
U10 - National Semi, LMC660 CMOS quad op amp
D1,D2 - 1N4148 General purpose switching diode
D3 - On-Semi, 1N5817 schottky diode, 1A, 20V
Q1,Q2 - 2N3906 pnp switch
Q3-Q5 - Fairchild, 2N7000 N-channel enhancement mode DMOS transistor
Q6, Q7 - Fairchild, J310 N-channel jfet RF amp
Q8, Q11, Q12 - On-Semi, PN2222A general purpose npn transistor
Q9, Q10 - On-Semi, MPS5179 NPN high frequency transistor
RF Board:
U1 - Microchip, PIC16C72(A) 28-pin, 8-bit CMOS microcontroller IC
U2 - 78L06 6V regulator IC
U3,9 - Linear Technology, LT1252 Low cost video amp
U4 - On-Semi, MC145170P2(P1) PLL Frequency Synthesizer with serial interface
U5 - Linear Technology, LTC1451 12 bit rail-to-rail micropower DAC
U6 - National Semi, LMC662 CMOS dual op amp
U7 - not used
U8 - National Semi, 78L05 3-terminal positive regulator, 5V, 100mA
U10,11- Philips Semi, SA612 (SA602, NE602) Gilbert cell double-balanced mixer IC
U12 - On-Semi, MC1350P Monolithic IF amplifier
D1-D7, D11,D13 - 1N4007, diode rectifier, 1A, 1000V
D18, D36
D10, D12 - Fairchild, SB530 schottky diode, 5A
D16, D23-D26, D39 - On-Semi, MV209 Silicon epicap voltage variable capacitance diode
D17, D21, D22, D29-D34 - 1SV149
D37, D38
F1 - Tyco/Raychem, RGE300 Polyswitch reset-able fuse
Q2 - ZVN4424A
Q5, Q21, Q22 - 2N5109
Q6 - 2SC2166
Q7, Q8 - 2SC1969
Q10, Q12, Q17, Q20 - Fairchild, 2N7000 N-channel enhancement mode DMOS Q23 transistor
Q11, Q13, Q16 - On-Semi, PN2222A general purpose npn transistor
Q18, Q19, Q24 - Fairchild, J310 N-channel jfet RF amp
I recommend the Edsyn 951SX Soldering Iron. This is an excellent iron and reasonably priced (around $100-$150 from Carlton-Bates).
e-mail: WB4VLQ
You can contact Elecraft at:
[email protected]
See Elecraft web site at:
www.elecraft.com