Well, you guys have given me quite a bit to think about here.  There is no Al wiring in the house--I've replaced virtually all the switches and outlets myself and it's all copper.  That said, now you've got me wondering if I messed something up when I replaced the outlet the amp is plugged into--something easy for me to check anyhow.  It never dawned on me that RF might be messing up the multimeter, and I think that's a very likely possibility.  One leg of my dipole crosses over the roof near where the shack is, about 30 feet above the room.  I'll try to verify if RF is the culprit this weekend.

As I mentioned in my first post, I'm only running the amp on this common circuit until I get the 240v circuit, which should be in the next month or two.

Thanks very much to all of you!
Mike

Well the voltage drop surprised me, and I have to wonder about the conductor size in that circuit.  It's one of the longer runs in the house, at about 30' horizontal run from the panel.  My house is one of about 20 small ranch styles that were all built in the same area by the same developer in 1983 and 84, so it wouldn't surprise me if the conductor size is smallish.  Regardless, I did inadvertently verify the breaker works several months ago by trying to power up an old Dentron gla-1000b that had problems.  I also did a lengthy test transmission using Olivia 8/250 and ran back to the panel and felt the breaker, and it never got any warmer than the surrounding breakers.

To clarify my tuneup method, I switch to AM, key the mic and quickly tune.  Then I'll switch it to SSB.

But no real issues for operating the amp at such low output levels?  (100 - 200 watts)

Until I can run a dedicated 240v circuit for my AL-80B, I'm currently running it on a 120v circuit that already has several things on it (2 computers, room lights, power supply for HF rig).  Naturally, if I try to drive it to max output I see a voltage drop and the lights dim, computers sometimes go nuts, etc.  My multimeter shows a nice stable 120 volts AC at the outlet with the amp off, and line voltage drops to about 70 volts when pushing output power above 600 watts.

For the time being I'm limiting my output to no more than 400 watts (and frequently as low as 150 - 200 watts) but I'm wondering if I'm causing new problems by running it that low?  I've been trying to follow W8JI's instructions for tuning up where I work up to about 400 to 500 watts and then reduce my drive power.

This is my first amp, so maybe I'm just being overly cautious, but I thought it might be worth a question here.  Am I harming the amp in any way by operating it in this manner?

Thanks,
Mike

The 5 ft. should have leg separation allowing you to lag the feet into rafters instead of plywood.  With the 3 ft. you'll only be able to get two of them into rafters (assuming 16" centers") and you'll have to do what Bob suggests and install some extra bracing for the third leg. 

I installed a 3 ft. tripod my roof for a 10' 2m vertical, and I wish I'd done the 5 ft. tripod instead.

Mike

Redundant.

Yep, same thing here in Alaska.

Few people these days remember that Hawaii and Alaska are both within the US.

I've been using nylon line to tie off the ends of my dipole, but when I got my 45' mast and needed to install guy ropes I went with 3/16" dacron.  I don't mind a bit of stretch in a line securing the end of a dipole leg, and if it eventually breaks it's easy to fix.  But when it's a big steel pole that might come crashing down against my house I thought fifty bucks for a 500' spool didn't sound all that expensive.

I am going to be doing this very thing as I'll be moving to a new house soon.  I was wondering about using that expanding spray foam stuff though, instead of fiberglass insulation or steel wool.  My worry is that the foam is usually urethane based (I believe--I may be wrong) and I'm wondering if that might harm coax sheath.  Anyone know if that might be the case?

Thanks,
Mike

I appreciate the comments re: dissimilar metals--I'll probably just get a stainless bolt, nut and washer and attach them using that, with the washer separating them.

This is great info--I appreciate the responses.

I did run across some 12.5 gauge aluminum wire, so that's an option too.  I'll probably stick with the 14 gauge to start with--the stuff is less than $50 per 1/4 mile spool, so it's pretty cheap.

Thanks,
Mike

Okay--that makes sense.  For some reason I had it stuck in my head that it's aluminum so it may not handle higher power.

Thanks,
Mike

I've been thinking about using either 14 or 17 gauge aluminum electric fence wire to make an 80m horizontal loop, but I was curious how well the wire would handle power above 100 watts.  At this point I'll almost certainly use the 14 gauge wire, if for nothing else because of the mechanical strength of the wire.

I can't imagine there would be any problem running 100 watts through it, but I'm curious if I'd have any issues using my AL-80B with it?

Thanks,
Mike

Great to hear--thanks!  I have a couple other questions, but I'll start a different thread so I don't hijack this one any further than I already have.   

Mike

I'm looking into using aluminum fence wire for a horizontal loop too, and I was curious if icing or even rain might have any effects on the uninsulated wire.  Any odd behavior I should look out for?

Thanks,
Mike

I'd be curious to see where those CATV drops are grounded to, and possibly try grounding to the same point.