You will want to use an external antenna tuner if you put it on the air in anger. Not because the pi network is not pretty wide range in impedance matching, but to make sure the harmonics are down to FCC levels.
Dave, W7UUU, has built a variant of this transmitter design (which is often referred to as the W1TS transmitter) and uses it actively. Dave, are you having a problem with harmonics? Maybe you're already using an external antenna tuner or a low-pass filter?
I had not planned to use an external tuner unless the antenna situation becomes sub-optimal. I have preliminary permission from my landlord to erect a full-size, coax-fed 80m/40m trap dipole arranged as an inverted-V so the match with the pi network should be very good. If my landlord and/or his wife decide they don't like my antenna, I may have to opt for something more stealthy and may need a tuner. Thank you for the advice.
I have a number of blocks of wood I use to support boxes etc for drilling and large hole cutting; with a suitable block and clamps, it's fine, but I'm much lazier than you!
Peter: There are several forms of laziness. Mine takes the form of procrastination. This transmitter project has been on the blocks for 45 years. That's right, it's in 1969 that my parents gave me "How to Become a Radio Amateur" and a Heathkit code oscillator kit for my birthday. I got as far as building a home-made tin "chassis" in the school workshop, but never populated it with parts. More recently, I became licensed in the USA more than two years ago and bought all the parts for this transmitter more than a year ago! They've just been sitting on the shelf!
It's true that work and family pressures were the main reason I didn't get the time to start building earlier. But it's also a maddening character streak: I like to get everything "perfect" and plan obsessively in advance. Result: things take ages to get done.
Martin, you should keep and cherish that box of FT crystals!
Al (K8AXW): I sure will. I'm 57 years old. Let's imagine I live to age 87. By then the crystals will be at least 90 years old!
FYI: I used to drill the tops of those chassis from the inside while on a plank of wood.
Allison: That's not always possible. There is a flange on the inside of the bottom of the chassis (for fixing the bottom plate) which gets in the way, even if you have a drill bit extender -- and I don't like extenders much, partly from a safety point of view. That places a limit on the location of the holes, because of the width of the chuck, among other things.
Thank you for the tip about using a plumbers' candle for lubrication.
The really cool way for the larger holes and odd shaped ones is a minimal set of drills and a Greenlee chassis punch set.
Good to have the endorsement, because that's exactly what I have. A set of conventional bit, and then eight Greenlee punches. These include the standard sizes for tube sockets etc. as well as some more exotic sizes, some of which are not made any more and had to be bought from an antique tool dealer. (Some components in these old ARRL books call for "intermediate" size holes that are no longer available in the Greenlee catalogue.)
A note on those crystals (FT243) many of those may be "dead" or very inactive now. The usual reason for this is the gasket has contaminated the crystal blank. They can be opened and with care to not break or chip they can be cleaned. That often restored full activity.
That's very useful to know. Fortunately, these crystals have seen duty relatively recently. I purchased them from Paul, K7IN, who was downsizing his shack and getting rid of older equipment including the crystals and a mint-condition Eico 720 transmitter. (I didn't buy the TX because of my "all-homebrew" philosophy.) I got the impression he had been using the crystals in that TX until relatively recently. However if there are any problems, I will follow your advice about checking the gasket. Thank you.