Tuesday, December 7, 2010

December 7, 2010 Activities

It is nice being on vacation - I can fool around with radio stuff.

I spent a few hours trying to salvage the dummy load I built a while back which could not get to work. Having given up, I purchased a kit from OHR (Oak Hills Research) for an air cooled dummy load. I tried originally to solder a set of 20 1K-ohm resistors in parallel between two copper plates but the plates act too much as a heat sink for my 60w soldering iron. I got the plans originally from K4EAA who sold me the resistors. At any rate, I could not get the impedance to stabilize to an acceptable value - too many cold solder joints. I decided to take it apart today and start from scratch. First I tried de-soldering and that did not work too well. I just ended up clipping them to salvage the resistors. So now I ask myself - what do I do with a bunch of stub wire resistors. I checked all the resistors for resistance value and they mostly came 1000 ohms +/- 2 until with a couple that were off as much as 10 ohms - good enough for a dummy load.

I dug out some old 14-3 Romex and pulled out the bare copper ground. I hammered a hardwood nail into a sawhorse and wrapped the wire around the nail head making a tight loop. I pulled the loop taut until the hole is just big enough to pass the resistor leads. I repeated this twenty times x 2 wires spaced 5/8 inch apart. I then soldered the resistors to these loops. I tested the impedance with a VOM as I soldered each resistor making sure I have a stable resistance value. I then coiled the assembled resistor assembly into a tight spiral making sure none of the wires touch. I then soldered the ends to the SO239 on the lid of the quart can. Checked the impedance again and it registers 50.5 ohms. I poured a quart of mineral oil into the quart can and the put the cover with the resistor assembly and voila - a nice accurate dummy load for the shack.

Anyway, this is a gift for the young Stephen Belknap - 12 yr old general class operator and part of the talented Belknap family of hams. I visited with them and they are such great people to be around - plenty of stories to share about all things radio.

Before bedtime I worked a station in Dover PA - W3OKC on the low bands - 80m at 3.560Mhz. It turns out he is a FISTS member as well and his number is the one after mine 15356 (mine is 15355) . He instantly sent me an e-QSL which I confirmed straightaway. There has been a lot of QRN of late and so W3OKC had power up to 200w. I was at 75W. We both exchanged 599 RSTs. Nice QSO - short and sweet.

I learned something else new today - there is an LED indicator on my radio that blinks green when I am at zero beat - between listening to the tone as a I turn the VFO - looking for the green LED to flash makes zero beating a cinch.

No comments:

Post a Comment