The 900 MHz amp I got the sweetheart deal on has arrived.
It's actually two amps, in fact.
The big one only has about 37 dB of gain. My thinking at the time was that its output at maximum input would not be sufficient for my needs. But now, my thinking has changed. If I feed the thing the maximum power from the exciter of 12 dBm average, the output power would be 79 watts average. Well, as we now know, the peak-to-average ratio of ATSC is 5 dB (at least it is 98% of the time), so that's actually 250 watts peak, which is probably too much (we'll have to get the thing on a scope to see for sure).
I bought that amp, plus a companion amp designed to boost the signal from -2 dBm to up to 5 watts. But I think, in retrospect, that given what I've learned that I'll probably just run the big amp by itself.
The first stage amp does have the advantage of having a power control pin that can be used to reduce the gain, but the exciter also has software output power control.
One thing that the big amp lacks is a PTT line (that is, something that can key the bias voltage for the modules on and off). This is something I'll likely need to add myself. The kind folks at the factory said they'd be happy to help with that when I got to that point.
It also lacks a cover. I'll need to get some sheet metal bent somewhere to fix that.
First step, however, will be trying it out on the air. But that will have to wait for a 28 volt power supply.
I'd like to publicly thank Ken and Lance - you two know who you are. I'd mention the company name, but I am not sure whether they would appreciate the publicity or not. If they would like a plug, I'll edit this post and add one happily. They are very nice people to deal with.