Hello W6uv,
If you can tune in 5 seconds, you have nothing to worry about. Improper tuning in my view includes all you mentioned plus trying to get the meters to read the manual tuning values when on SSB.
Also not having a device to read watts at the output of the amp; switching bands while the amp is in the operate position. I am not condemning these inexperienced ops, just identifying their mistakes which could help them in the long run. All you have to do is read the amp forum often to see how confused some are. This also includes long time ops with no amp use experience.
You  could also include too much drive when adding drive does no increase power out from the amp as well as prolonged tuning exceeding the max currents.
I think I did all of the above when I first bought an amp.

Frank

Dave, I am glad to see that you clarified maximum amp power in your post. So many newbies read posts by others and think one has to use maximum drive to tune and that is not the case as you know.
Once the drive is set say to 50 watts, then you need to tune for max power out at 50 watts drive to get the efficiency you mentioned. Also It is my perception that many tube failures are the result of improper tuning with max drive by inexperienced operators. If I am wrong in my thinking I'm sure someone will call my hand.

Frank

A five band hex beam on a push up pole against the house or garage might be a consideration. One is available for around 500 bucks or less delivered. Requires only a TV type rotator.
A great two element beam type antenna, 25 lbs. or so with a small footprint.  One 50 ohm coax for all 5 or 6 bands. I use RG8X, not real expensive. Will work OK at 30 to 40 ft.
If you want to build your own, Max gain systems has parts and wire to roll your own.

I forgot to mention that if your multi-band dipole is a fan dipole, forget the  ladder line and run coax all the way. You can still use your tuner with coax.  Then install a MFJ or other 1 to 1 choke/balun to prevent RF on the coax up near the antenna.  I also use an MFJ 915 line isolator at the transceiver on my  antenna output. My field strength meter indicates no stray RF in the shack.

Frank

Could you give a little more info on the design of your antenna and the tuner info? I would vote for the feed through coax fittings installed in the metal building wall spaced to match your ladder line.
Then extend the shortest possible ladder line to your tuner balanced line terminals. You can use pins or solder to make suitable connections on the ladder line ends for the feed through as stated before.
The coax feed would probably work with your so 239 fitting on your tuner but not as well as the ladder line feed. At any rate ,depending on your antenna design, it may be touchy to tune on some bands. I would also buy me an inexpensive field strength meter if concerned about the RF exposure from the 4 ft. above your head. No guessing that way. Both Tisha and WB6BYU know more than I do about tuners no doubt in my mind. I do not remember if you mentioned how much power that you would run. That is a consideration for RF as you know.

If you have any old 73 or QST Mags. check Gotham Antennas in the advertisers index. They used to be in Florida. It may have been that company.

W7yen will  probably make you a cable as he sells all sorts on ebay. Just email him and ask if he will. I have bought a couple from him over the years for around 20 bucks and found them to be entirely satisfactory.   Genrlvideo@aol.com :        http://www.ebay.com/itm/8-PIN-MINI-DIN-LINEAR-CABLE-YAESU-FT-817-FT-847-FT-840-/350415986192?_trksid=p5197.m1992&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D14%26meid%3D7381095190316509377%26pid%3D100015%26prg%3D1006%26rk%3D1%26sd%3D350415986192%26

Frank

Hello Jack,
You will need a din for the radio end and a RCA plug for the amp. Here is a link to buy one for around 20 bucks. Most standard din plugs will not fit your radio so best easies way is to buy one made up for your specific radio.  http://www.ebay.com/itm/8-PIN-MINI-DIN-LINEAR-CABLE-YAESU-FT-817-FT-847-FT-840-/350415986192. This is one source, there are probably some others.
Good luck


Frank

The instructions read to tape the feedline to the boom. Tape the choke to the mast. The braid length feed pigtail is shown to be 4 inches. The other pigtail is not dimensioned but could be determined by measuring after the braid is connected and the coil is attached to the mast. With only 4 inches on the braid pigtail the coil will be very close to the boom and attached to the mast.  I would suggest using nylon or plastic ties in addition to the tape called for in the instructions. Running the coils around the boom is not an option if you are to follow the instructions and would most likely defeat the choke, but don't ever recall anyone who installed one that way, so can't be sure.

Clint gave you so good advice so don't ignore it. Most old towers are not safe to climb so don't do it. Forget the base as they are usually in concrete so plan on a new one fabricated or bought from the tower maker.

On your HDTV shutting down when using the transceiver, I would suggest using a good drop cord to plug the HDTV into another outlet or so to see if it still does that. Sounds like a bad connection on the same circuit, just a guess.
An amp will give you the opportunity for many more QSOs than a good antenna alone. Both would be a better situation, but in order of priorities, my suggestion would be an amp.
I always answer the best signal heard when calling CQ and I would bet most others do also. I support what W8JX and AD6KA wrote for an amp.

Frank

My suggestion would be Ameritron AL80B, AL 80A, AL811H, AL 811 in that order and of descending price.
These are a good value for the money and cover the bands well.

I have 5 acres of mixed hardwoods and pines and a group of buzzards roost there so often the ground has white spots. They have not roosted on my 5 band hex beam. I would probably have to talk to them if they did but nothing serious, just a warning not to come back.

Eric,
10 meters, my load is 8 plus 2 lines. The plate is at the end of the white beyond the number 15. The preset is 8 in the manual. I do have a 10 meter wire on my hex beam, but my tuned input is peaked for 12 meters a favorite band. The same coil in the tuned input is used for 10 and 12 meters. Likewise I peaked 17 meters which shares a coil with 15 meters. I like the warc bands.
I can only get about 750 watts out on 10 meters which I don't often use. I get about 900 on 15 meters on some frequencies., less on others further from resonance on my antenna.
I would suggest that you make several copies of the Amateur tuning log from your manual and record your amp settings. This will assist you in speedy tuning for switching bands. I also would
suggest that you copy the presets and always start from there on your load and plate settings. I usually advance the load about a half line after tuning for the max power out. W8JI suggested this I think.
Also I find that all my current readings are way below the max so I don't tune by them, I go  by the watt meter. Should I see a high grid current while tuning, I go to stand by if I cannot immediately drop it with the load and plate tuning. I have a clip board on the desk with the presets and my particular tuning settings  even after over 24 years with the AL 80A.
BTW, WIK, Steve, nailed your problem so congrats. there Steve, you haven't lost your touch. That was the one thing I called your attention to that was not normal when you answered my questions, but I was not convinced that was it like Steve. Also your old 3-500 is most likely OK, as I just put my 17 year old Amperex back in after  storage for over 4 years.
Good luck  Eric,and I'll be listening for a loud signal from you. My advice is don't run the old amp at max out. You won't see any improvement of 1K over 850/900 max. is my experience.

Frank

Eric,
You did well on the questions, the bad news is that everything looks normal except the load should be somewhere around 5 on 20 meters. The manual preset is 5.5 and I just checked my amp loading on a hex beam is 5 for about 750 watts out with 65 watts drive. Tom W8JI who designed the amp writes on his site that the power out should be about 12 times the drive power.
Here is what I would suggest if you feel comfortable doing it safely.

1.Connect a watt meter and dummy load to the amp output. Don't connect the ALC for this.
2.With the amp on standby and the transceiver on CW mode, 100 watts drive, key the transceiver and see if the power out is 100 watts. This will make sure your coax and transceiver output
are OK and the transceiver is not backing down on power under load bypassing the amp.
3. If this checks out OK, I would suggest checking the tuned input for 20 meters only at this time.Here is how I did that on my AL 80A:
Take all the screws out of your amp cover, and slide it back to expose only the tuned input behind your band switch. You will see a top, horizontal group with three openings for a tuning tool. Ameritron has the tools or can tell you what size to buy. I had one about 40 years old but don't know the size.
On the top horizontal group, the openings are as follows left to right. 10/12; 15/17: and 20 meters is on the right side. Set the amp up for 20 meter only adjustment at this time.
There is another three openings on the side of the tuned input and they are as follows from top to bottom in a vertical configuration. I suggest that you write these down for future use.
They are top to bottom 40; 80; 160. These are not identified on my amp so you might want to save the info. Ameritron gave the info to me when I had a similar problem to yours.

Insert the tuning tool until it engages the 20 meter slug so you can turn it. Make sure the amp cover is only exposing the tuned input for safety purposes. The cover should be heavy enough to keep the interlock engaged , if not put a book or other weight on the cover.
Turn on the transceiver and amp. Set the transceiver power on 5 watts drive out in the cw mode. Make sure that the radio and the amp are each on 20 meters and the dummy load is connected. Turn the amp to transmit and key the transceiver with the 5 watts drive. Tune the plate for max out on the watt meter, then tune the load for max out.
Go back and tune the plate again for max out. Advance the load control for about a half line and you are ready.
Turn the tuning tool and watch the watts out, if they increase you are turning the right direction, if not go the other way. Using the tuning tool, peak the watts out. Once the watts out are peaked the tuning is complete. Using only 5 watts drive with the amp in transmit won't hurt it or the dummy load and you should get about 45 to 50 watts out on a watt meter. The watt meter does not have to be accurate as you are just using it to peak the output.

Keep the direction and number of turns in or out in mind as you do this. In case it does not help you could retune the input back to near its original spot.

This is how I did my AL80A and it works. There are other ways to do it I'm sure but this will work to check the tuned input adjustment for 20 meters and is what I suggest you try.
Let us know how you make out and be careful always aware of where your hands are around high voltage. If this does the trick for you, Check the other bands that are in the horizontal top group for max out like you did the 20 meter. BTW, I use 65-70 watts most of the time on my Ten Tec Orion to drive my amp.
Good luck

Frank