Probably 120 cycle hum instead of 60, and likely the filter caps.  In a rig of that vintage and earlier, I'd consider replacing the filter caps at the first hint of hum.  While you're at it, consider replacing any and all other electrolytic caps in the rig.  When the others fail, and they will, troubleshooting can be much more difficult that bad filter caps.  

I had a few NPNs in the junk box and found that the specs on the 2N2222 say it can handle 800ma. OK.  Wasn't aware that it would be that high for a 2N2222.  Anyway, built and installed the circuit and it works just as advertised.  

There's at least one rig (Elecraft K2) that's sensitive to the amp's relay switching speed.  It brings up carrier very fast before the amp's relay has transferred, thus seeing a high SWR from the open circuit.  The mod results in a higher than normal DC voltage being applied to the relay coil momentarily, thus speeding up the relay activation.  

I have the amp on the bench today and thought I'd install the K6XX circuit for speeding up the antenna relay.  I wonder what transistor other Ameritron amp owners have used in this circuit -the relay reportedly draws around 100ma.  

The 765 does not in its stock form.  There are a couple of different mods available to add it.  One was published in QST and was rather complex.  The other, from the same source, is pretty simple and works every bit as well.  I have modified my 765 and like the result.

I believe the 201 MK III came factory equipped with 572Bs.  MK II was the last with 811As.

You've just discovered one of the great unknown facts about RCA TVs!  I struggled with this one for months before finding it.  The large screen RCAs have switching supplies with NO shielding of any kind.  The broadband noise radiates directly through the plastic cabinet, and very little actually gets out through the cables.  I found that the audio out cables were especially troublesome, but choking them down helped very little.  The ultimate solution is to NEVER buy an RCA again!  All large screen TVs do NOT have this problem - I've tested Toshibas, Sonys, Hitachis - no noise.  I finally went down to the local Home Depot and bought a remote control switch that the TV plugs into, allowing me to completely kill power to the set without getting down on hands and knees to unplug it.  Of course, the RCA doesn't like this, and presents you with the initial power-up menu when you turn it back on.  Another thing that worked to some degrees was an MFJ noise cancelling unit, but I had to run a sense antenna under the carpet to just below the TV in order to pick up enough of the noise signal for the cancelling unit to work properly.  By the way, this problem with RCAs was first reported in a letter in QST several years ago.

Give one of the switching supplies like the Astron or Alinco a try.  If you don't operate 160 meters, chances of your having any problems with noise are almost nil.  As you know, these supplies are very small, and they don't produce audible hum from mechanical vibration of the cabinet, etc.  Otherwise, you won't notice a difference unless you're using an Elecraft K2, in which case you don't want to put an Astron linear supply within 6 feet of the rig because of transformer flux leakage modulating the rig on transmit.  Switching supplies have been used inside some of the more common transceivers, such as Icom's IC-765 and have proven very reliable.

I use a serial port for a homebrew interface box for PTT, CW, and FSK lines.  A separate USB/Serial port converter is used to interface the radio itself to logging programs via a W1GEE adapter which takes the place of the much more expensive Icom adapter and performs perfectly.  

Did you try ALPS?  I think they're still in the pot business.

The total length should be about 1005 divided by the frequency of operation in MHz.  For a square loop on 20, this works out to about 17.8' on a side.  I use loops instead of dipoles in cases where the support structures (usually trees for me) are too close for the dipole length.  A triangular or delta loop also works well if you have just a single high support point.  The feedpoint impedance for the loops will be 100-120 ohms in my experience, and I match them with a matching stub at the feedpoint so I can feed them with 50 ohm coax.  If you want to use the loop on multiple bands, open wire or ladder line works fine with a tuner.  The loops can be fed at different points for vertical or horizontal polarization - check out the W4RNL website for lots of loop info:
http://www.cebik.com/radio.html

If everything is original, you might want to think about replacing the filter caps.

You can buy them from West Mountain Radio.  They sell them in bags of various quantities.  I don't know if their price is as low as other sources.

Hogwash!  The vast majority of interference with electronic equipment is due to absurdly poor design of the interfered-with equipment with no consideration at all given to preventing such problems. The FUNDAMENTAL signal radiated by your antenna is causing the problem - not harmonics, as you guys seem to be suggesting.  Properly designed solid-state transceivers have effective low pass filters, switchable by band, that adequately attenuate harmonics.  Those who used tube rigs understand that in many cases the harmonics weren't getting out through the antenna at all - they were being radiated through improperly shielded meter cases, poorly made cabinets that leaked RF, etc.  One manufacturer who understood the problem was E.F. Johnson and a properly assembled Johnson transmitter could be used in weak-TV signal areas with little chance of harmonic interference to the TVs in the area.  On the other hand, Drake and Heathkit were among the worst offenders when it came to harmonics.  I'm sure there are many late-model solid-state rigs with the same poor harmonic performance, and for reasons similar to the poorer performing tube rigs.  It has nothing to do with whether the final amplifier is tube or transistor.  

I ordered something from them last week and it shipped OK, but can't get to their website today either.  

I would say NOT.  Your symptom sounds like radiation from the power supply of a TV (unshielded switching supply).  Try unplugging your television and see if the noise disappears.  Just being turned "off" leaves the power supply ON so that the set can respond to the remote control.