Elecraft K2 - Serial Number 007239 Build. Day 24

Hours 1:31:00    Total Build Time:   43:17:00     Mar 11, 2012


Back to work on the K2 again.  This build session consisted winding several toroidal transformers and mounting them to the main RF board of the K2 radio.

T5 toroidal transformer

T5 toroidal transformer

Mounted position of T5 toroidal transformer

T7 toroidal transformer

The next two shots show the winding of the T6 toroidal transformer.  This transformer used a bi-filar winding technique where the red and green wires are twisted together before winding the coil.

T6 bi-filar toroidal transformer

T6 bi-filar toroidal transformer

Elecraft K2 - Serial Number 007239 Build. Day 22

Hours 0:31:00    Total Build Time:   41:46:00     Jan 08, 2012


Well it has been a long time since I have worked on the radio.  I thought that I had better start working on it so I could get it done.  Tonight I started slowly winding one more RF Choke.  The Choke is RFC11 and it is located on the bottom of the circuit board.

RFC11 installed on the bottom side of the RF board

Ramsey Headphone amplifier project 12/21/2011

Ramsey Electronics - Stereo Headphone Amplifier Kit.   1 hr 30 minutes construction time

This evening I took a break in the construction of the Elecraft K2 to put together a Ramsey Electronic kit that is a Headphone Amplifier (Christmas Present for my Father).  The amplifier takes a line level audio signal and amplifies it using 2 lm389M IC amplifiers.

Ramsey Stereo Headphone Amplifier kit

Compared with the Elecraft K2 amateur radio transceiver that I am building, this project seems really simple.  The circuit board is single sided and doesn't appear to have many components on it.

Single Sided circuit board

All the parts for the kit are bagged.  There is a good manual that comes with the kit that explains how the amplifier works.

Amplifier parts

This is a shot during the construction of the kit.   The sequence of parts installed on the board are from the top to the bottom going left to right.  The Elecraft K2 transceiver kit components were installed (it seems) based on the hight of the component.  The smallest components being installed first.

Voltage regulator

LM389N amplifier ICs

Below is a shot of the finished circuit board.  Before mounting the circuit board into the case, it was tested.  After checking to see that there are no solder bridges and that the parts that have to be installed in a certain position (like the IC's and the Electrolytic capacitors), it was time to power up the amplifier.

It worked the first time!   Powering up a kit for the first time is always exciting.  You don't know if it is going to work or not.

Completed Circuit board

The Ramsey Headphone line amplifier kit also includes a case.  The case for the amplifier is included in the price of the kit.  In addition to the kit I also purchased a AC power adaptor.

Case for Amplifier

Hardware for the case

Circuit board mounted in the case

Well here are the photos of the finished product.  After the circuit board was mounted in the case, I hooked up the amplifier to my Directv receiver line out.  Next I hooked up some Bose earbuds to test it out.  It didn't take much to drive the earbuds.  I barely had the volume adjusted from off cause it was so loud.

Completed kit.  Front

Completed kit. Rear

I am pleased with the quality of the kit.  The assembly was straight forward ( After working on the Elecraft K2).  In the future I may consider building other Ramsey electronic kits.

Elecraft K2 - Serial Number 007239 Build. Day 21

Hours 1:00:00    Total Build Time:   41:15:00     Dec 10, 2011


Well, I reached the section in the manual where it is time to wind the toroid chokes.  First the toroid  cores were separated into their groups.

Toroid cores

tinning the leads to the Toroid choke

The first RF Choke wound was RFC14.  It is shown installed in the photo below.  The manual had good instructions telling how to wind the choke.

RFC14 installation

Size of the RF Choke

 Here is another shot of RFC 16 which was also installed today.

RFC16

Elecraft K2 - Serial Number 007239 Build. Day 20

Hours 0:33:00    Total Build Time:   40:15:00     Dec 8, 2011


Tonight I worked on steps 13 and 14 on page 55 of the manual.  On these steps, the crystals are grounded to the circuit board.  Crystals X5  & X6 use a single ground wire from the top of the crystal to the circuit board.  Crystals X7 - X11 use two ground wires from the sides of the crystal to the circuit board.

Crystals X7 - X11 use 2 ground wires from the sides to the circuit board

Crystals X7 - X11 use 2 ground wires from the sides to the circuit board

Crystals X5 & X6 use a single ground wire from the top of the Crystal to the circuit board

Elecraft K2 - Serial Number 007239 Build. Day 19

Hours 1:25:00    Total Build Time:   39:42:00     Dec 7, 2011


Today started making a circuit modifiaction connecting components to the MC145170 PLL Synthesizer chip. 

Additional modification near MC145170 (PLL Synthesizer w/Serial Interface) 

Next Crystals were installed.  So far 3 of the crystals have been grounded.  There will be a special grounding technique that will be used on X7 - X11 crystals as shown below:

Filter Crystals X7 - X11

Filter Crystals

BFO crystals

Elecraft K2 - Serial Number 007239 Build. Day 18

Hours 0:32:00    Total Build Time:   38:17:00     Dec 6, 2011


I am off to a slow start today working on the K2 RF board.  The past week I was on vacation to the Western Caribbean on a cruise.  Now that I am back I need to get back to work on the radio.


Today I started out installing some RF chokes and Electrolytic capacitors on the board.  The RF Mixer Z6 was also installed.

Z6 - RF Mixer