Tuesday afternoon, March 14, 2023
I seldom write updates to this blog in the middle of the day, but I have time and the inclination, so here goes.
Last night I replaced the faulty dual needle watt/SWR meter in my MFJ Differential T antenna tuner. I found a suitable replacement (MFJ) on eBay about $22.
As you know, when you buy ham gear from a non-ham seller on eBay, its kinda pot luck if what you receive works or not. In the case of this tuner, it was in partial working order.
The original meter (pictured) was perpetually stuck at the 10 watt level. You could not “zero” the meter using the adjustment for that purpose. Additionally, the forward deflection of that needle was dead; no movement, no nuthin’.
Now the meter I bought is slightly different than the original. The replacement has a scale of 0-300 watts, while the original was 0-200 watts (2000 watts on the high scale). I suspect there’s an adjustment on the metering circuits to make the meter read more correctly; right now, 100 watts is showing up lower than that on the power output scale.
But does accuracy in the output really matter? With a dual needle meter, you’re really looking for the lowest SWR with highest output … whatever that output is. It isn’t like I need complete accuracy in readiing power out. Its all relative. Max power out with smallest reflected power.
The new meter works like a charm; I was initially concerned that maybe the problem was the metering circuitry and not the meter, but that was not the case.
BROKEN FEEDLINE??? Someone or something snagged my 300 ohm twinlead feedling and snapped it …. actually it looks like it was pulled in two. My wife said there are tire tracks on that side of the house, and it makes sense. The broken end of the feedline is up in a tree about 20 feet, as though it had been stretched taut and snapped, shooting it up in the tree limbs in the process.
The high winds of 10 days ago broke one end support rope, but other than the feedline, I think the antenna is intact. If I can pull the center down (if the support rope isn’t grown into the fork of the tree), I’ll replace the feedline with the new feedline I bought that’s higher gauge wire but still 300 ohms.
One of the side effects of soldering last night is that — for some reason — I can still smell it. Like hot plastic somewhere. I asked my son if he smelled it, and he says its in my head. No, its in my nose apparently.
I went ahead and ordered 150-feet of new copper wire and also 100 feet of 300-ohn twinlead, all of which is here now. I can Hopefully this week my son and I can drop my antenna down and replace the feedline. We’ll see!
73 es CUL …. de KY4Z …. SK SK …. (dit dit)