Wednesday, August 25, 2010

160 Meter capable

My K2 is now 160 Meter capable - but not without a few heart stopping moments along the way - all caused by myself, of course.

I've posted previously about my phobia with opening up the K2. My philosophy is, "If it ain't broke don't fix it" or put another way, "Why jump out of a perfectly good airplane?". But, if you want to add options to a K2, you have to open it. I guess another way of putting it is, "If you want to make mayonnaise, you have to break some eggs". So I took a deep breath and proceeded to crack a few eggs.

In whole, the procedure wasn't as bad as I had feared. I installed the 160 board without any difficulty. As it turned out, all I had to do was remove one jumper from the K2's RF board, add three capacitors and do the actual physical installation of the board. I was lucky enough that my K2 is of recent enough vintage that I did not have to swap out two designated capacitors on the RF board. The existing ones were of the right value. I don't enjoy replacing components. Too much chance to do damage to the circuit board - and that's with 22 years of electronics repairs under my belt. I've seen "simple procedures" turn into deep doo-doo.

The alignment, such as it was, was a piece of cake. Using my OHR Wattmeter, I was able to peak L3 and L4 for maximum power output on both 80 and 160 Meters. If I so desire, I can go past 10 Watts out on both bands without breaking a sweat.

The bad things started happening when I started buttoning things back up. The first piece to be put back together was what Elecraft calls the heat sink. The K2's two PA transistors attach to this sheet o' metal (which also acts as part of the housing) in order to transfer heat away from themselves. However, there are two fiber spacers that go between the transistors and the circuit board in order to insure that the transistor bodies A) stay away from the circuit board and B) stay close to the heat sink. Of course, in the process of putting things back together, one of the two fiber spacers went into orbit.

I got out the heavy duty flashlight and checked the basement floor for what seemed like an eternity. I checked my pockets, I checked my socks, I checked my sneakers, I checked everywhere, to no avail. Then I did what some "Old School" Catholics do when they lose something. I said a short prayer to St. Anthony, to ask for his aid in helping find this minuscule piece of insulating collar. In a short while, I was hit with an inspiration. What if the darned thing had never hit the floor? I decided to check the pockets of my antistatic mat. Sure enough that's where the little bugger landed! No need to call Elecraft and wait for a week while new ones were delivered. Thanks, St. Anthony!

Having everything put back together - heat sink, bottom cover, top cover - I connected the antennas, plugged in the key and external power supply. I turned the unit on and ....... no receive audio! What the ........ ??????? (Break out the defibrillator, Honey!) Plugging in headphones ensured me that I was still able to hear received signals; but ...... ????? I disconnected the top cover completely and ran a 9 Volt battery across the speaker terminals. I heard the satisfying crackle which indicated that I had not somehow damaged the speaker. But that probably couldn't be anyway, as I was not getting anything from either the internal or my external speaker.

Slow down, take a deep breath and figure out what's wrong. The thing was working a half hour ago - what stupid thing did I do? It had to be something stupid that I had done.

Sure enough, it was.

When plugging in the wires for the speaker, I had placed the connector on the two pins where you would hook up the internal battery - if I had one! I removed the connector and placed it where it was supposed to go and viola' - sweet audio came racing out of the speaker(s) both internal and external depending on which I had chosen. (You can take the defibrillator back to the hospital, Honey!) I was listening to N1ZZ call "CQ DX" via CW for a few minutes and then went up the band a ways and went into LSB mode to listen to some ragchewing. Everything sounds great! I can even get the K2's internal ATU to get the G5RV down to about a 1.3:1 SWR. But I'm not kidding myself into thinking that that's a long term working solution. Gotta get that 160 Meter vertical built before winter sets in - but I'm sure that will be another story.

72 de Larry W2LJ
QRP - When you care to send the very least!

1 comment:

  1. This is a great post Larry It was a hoot to read. We all can relate to dropping a part and for some reason it appeared to vanish. I had a smile on my face as I too have been down that road. Glad all worked out and the rig is up and running. I just finished removing the top covering of my K2 to put the KPA100 I am building through a checkout. All went well cover is back on until the KPA100 is done.
    Good luck on 160m