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 knob's parts

The brass insert back (note side hole to counter balance the set screws)

The brass insert front

The knob without the o-ring

The knob inside view (with brass insert out)

The o-ring

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

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