Battery Eliminator, Aerodyne's design.

[Aerodyne]

I can't do better than to echo David's suggestion about a dummy load to see the HT drop. I think 27mA is rather a high value and I believe you may find the HT approximating more closely to the requisite 90V under the working conditions of the average all-dry receiver. It would be perfectly possible to regulate the HT but IMO an unnecessary complication and expense.
Interested to see how the final build looks, Mark. Pics when possible, please!
-Tony