After a long hiatus, I have begun using Tech Pan again (a friend gave me an out-of-date 50 sheet box of 4X5). I used Tech Pan extensively in the late 1970's and early 1980's, developing it in POTA and a buffered POTA variant of my own devising. My results were excellent but EI's were very low.
I have been using Pyrocat-HD with Delta 100, Pan F+, Acros 100 and TMax 100 with outstanding results. I have also been testing a variant (suggested by Patrick Gainer) with these films that replaces the catechol 1:1 with Hydroquinone and eliminates the bisulfite and bromide (results - so far -are fully equivalent with Pyrocat-HD). I have been testing Tech Pan in this Pyrocat-HD variant developer and the results have been excellent.
Phenidone: 0.2 grams
Hydroquinone: 5 grams
Dissolve these chemicals in a small amount of methanol, then add Ethylene Glycol to 100 ml and mix (I do these steps under a ventilated lab hood wearing Nitrile gloves). The Ethylene Glycol acts as the preservative, so the bisulfite is not needed. I am not having film fog problems, so I eliminated the bromide, as well.
Potassium Carbonate: 100 grams
Dissolve the carbonate in 70 ml of boiled deionized or distilled water. The resulting volume of solution will be 125 - 135 ml.
As a starting point, try an EI of 64 and develop in 10 ml of A plus 10 ml of B plus 1000 ml boiled deionized or distilled water (the resulting one-shot solution will be a yellow-amber color). This is the 1:1:100 dilution. In a small tank or tray, develop Tech Pan for 12 minutes at 21 deg C with no agitation. Rinse with water and Fix in a non-hardening Fixer (I use TF-4).
The resulting D-Log E curve is similar to the ones produced by Tech Pan developed in POTA and Technidol.
If you look at the Photographer's Formulary Modified Windisch Developer, the working solution concentration of catechol is .3125 grams/liter. This suggests that a 6:6:1000 dilution of Pyrocat-Hd or the Hydroquinone variant would also work and my initial tests with this dilution confirm this. A suggested starting point is an EI of 64 for Tech Pan developed for 16 minutes with no agitation at 21 deg. C.