Actually what you're measuring isn't far off.

The T11 has a "typical max SWR of 1.8" but that's not guaranteed, and most of your readings are below that.

I don't have a T11 but do have a T8 and also had a T6 and noted the coax positioning is pretty critical.  Tennadyne in their original instructions (mine was made in Texas, part of the "original" Tennadyne line) recommended tying the coax to the lower boom and running it along the lower boom from the feedpoint back to the center bracket.

I tried that, and SWR was bouncy, and there was common mode current coming back down the shield.  So, I rearranged the coax routing based on what I'd seen in many military and commercial LPDA applications, where they let the coax "droop" from the feedpoint down to several feet below the antenna, only pulling it back up towards the antenna at the center bracket where it then forms a loop to go down the tower or mast.

Common mode issues went away, and SWR was flatter: So, I left it that way, forever.

Tip about replacing this type of transistor (irrespective of part number):

Loosen the two machine screws (Allen type, usually, but may be Bristol or Spline or almost anything) that mount the transistor first, before attempting to unsolder the emitter or collector tabs.  This will make the thermal transfer ("heat sinking" effect) from tabs to the heat sink much less efficient, and allow the tabs to be unsoldered pretty easily.

If you leave the transistor firmly bolted down, it takes an awful lot of heat to unsolder the tabs, and that can burn the board or degrade the board and attached components.

When soldering in the new device, I just place the machine screws and turn them in but not fully tight, until after the soldering operations, and then fully tighten them -- for the same reason.

There is likely a tiny amount of thermal grease on the back (flat mounting surface) side of the transistor where it rests against the heatsink.  I'd clean that away, make sure the HS surface is very clean, then apply a small amount of "new" thermal grease on the backside of the transistor before placing it onto the heatsink.  The Wakefield white thermal grease works fine, but there are other choices.  Don't use much -- the layer of the grease should be very thin.

Based on the reported observations, it does seem like the driver transistor failed and the output transistors are still good.  And of course it's true the TE "Repeater" amps use no biasing, they're Class C and intended for FM use only.

I have a 6BTV and have installed a lot of them.

They can be "adjusted" for SWR <2:1, using a proper radial system, for most of 10m, all of 15m, all of 20m, all of 30m (as narrow as that band is!), and almost all of 40m.  I set mine to "dip" to nearly 1:1 near the center of those band segments.  On 75/80m, it's another story altogether and can only cover about a 50 kHz slice of the band <2:1, if that.

So, if you use the antenna on 80m, a tuner will really be required unless you only operate in a very narrow segment of that band.

But on the other bands you really shouldn't need one, if you spend some time adjusting the antenna itself.

I'm using an elevated installation (base about 22' above ground) with "tuned" radials for each band, so mine has 20 radials attached (four per band, and using the 40m radials for 15m also) and after making the antenna adjustments, I "fine tuned" the whole system by adjusting radial lengths -- which does work.  With the radials sloping as they are (they slope about 20 degrees from antenna to ends), I achieved a 1:1 or very close to 1:1 SWR on a center frequency in every band.

Good "used" rotators include the Alliance HD-73 (very good rotator, no longer made but I see them used pretty often), and the Hy-Gain CD-45 (still made; it's strong and accurate but has no brake -- with small antennas you shouldn't really need a brake).

The HAM-series Hy-Gain rotators (HAM-M, which is very old, HAM-II which is quite old, HAM-III which is pretty old, and HAM-IV which is still on the market but has been made for decades) are also available used and even reconditioned with warranty, pretty reasonably.  These all have a brake, so they will support "longer" antennas.

CATS sells used/reconditioned rotators: http://www.rotor-doc.com/sales.html

So does Norms: http://www.rotorservice.com/

In fact, I think Norm bought out all remaining Alliance rotator inventory, including parts, when they went out of the rotator manufacturing business.

Don't know but gray line propagation doesn't last three hours.   Gray line is pretty short lived, and usually occurs around sunrise and sunset local time; lucky if it lasts one hour, let alone three.

You've got something else going on there, I suspect.

My first guess after reading the latest dialog on the symptoms is the input isn't even connected.

See if you can trace from the RF INPUT connector to the base of the driver stage; I'd guess something's open (or possibly shorted).

I see TE used a "regular" amplifier PC board for the "repeater" version, and simply omitted the relays, preamp, RF sensing circuit, etc -- and substituted jumpers and coupling caps and stuff in place of the "normal" relay circuitry.  Something might be open there.

There sure is.

I was on 2m AM and CW, and then tinkered with SSB (very new mode on 2m in the late 60s) before ever using 2m FM other than just messing around modifying commercial Motorola and GE rigs ("taxi" radios).

2m is a huge wonderland, and FM is probably the most boring part of it.

Be careful with the antenna installed so low to the ground on a tripod in the school yard.

Assuming it's not behind a big locked gate and wall and might be accessible to kids or others walking by, this is dangerous.

The roof is a much safer environment for a transmitting antenna.

Even up there, don't let the "ends" (tips) of the radials come in contact with the roof or come close to anything flammable.  In "wet weather" (very high humidity, or rain), people are most surprised how far an arc will travel even with a 100W transmitter.  The tips of the radials are all high voltage points, and I've arced right across and through what many would consider to be pretty good insulators -- usually in wet weather.

Use ceramic or glass insulators and lead ropes at the ends of all the radials.

Anything's possible, but this is a pretty big re-build.

Not just changing the heterodyne oscillator crystals (pretty easy) but also their tuned circuits in the het osc cathode follower; as well as the 2nd TX mixer tuned circuits; the driver/preselector tuned circuits; and the final power amplifier tuned circuits.

A lot of stuff to change.  Worth it?

I agree with Dale.

Below 450 MHz or so the real thing to watch out for when making transitions is the quality of the adapters.

I've seen some "imports" (and "Radio Shack" types) that were horrible and quite lossy, evidently made of materials that probably shouldn't have been used for this.

But the U.S.-made Amphenol, Kings, Pomona, Trompeter, et al (people who are qualified to manufacture mil-spec connectors and adapters) are very good and have no measurable insertion loss up through the VHF spectrum.

There are things you can do to "track down" noise sources, but an S7/S8 noise level on 40m really isn't bad.

Many times my noise level on 40m is S9 at home (with no man-made noise sources at all -- it's all atmospheric) and it's easy to make lots and lots of contacts, since "station" signals are well above that.

The Butternut needs a good radial system, of course.  What kind of radial system are you using?

Of course it needs a source of DC current to work.

Did you check to see if the 14Vdc going to the amplifier power terminals remains 14Vdc after you drive the amplifier with 10W?

Did you check to see if the 14Vdc is arriving at the transistor collectors?

The photos show no signs of overheating or obvious abuse; of course, transistors can fail without any telltale external signs (a fast transient might do that), but with RF amps like these, they "usually" fail over time from overheating, and that leaves some signs which aren't evident in your photos.

"FB" means "fine business," and is equivalent to "very good" or "I like it," etc.

Never heard "full FB."

As I recall they were $10 each.  You might contact Frank K2AW if he's still around...he's the one who had them made and sold them for decades.

It's actually very easy; however I never use more than 3-4 memories anyway. 

I can't think of anything fascinating enough to send that requires more than four memories.

For contesting, I use:

1.  CQ de (my call)
2.  QRZ?
3.  599 05 (or whatever the exchange is)
4.  TU de (my call) -- or something similar to end the exchange

Can't even imagine what I'd do with the next four.

For casual operating, I don't use any memories other than the one between the ears which I admit isn't as good as it once was.

Also, my memory isn't as good as it once was.