[Milsurplus] Identifying a WW2 improved WW2 SCR-718 high altitude meter

[Dongen, Nico van]

I'm trying to Identify some sort of prototype improved WW2 SCR-718 high
altitude meter. It came with a scoop indicator I-152-C that is date
marked Aug 1945 and with it is the Tx/Rx unit that I think is wrongly
labelled.
I expect this is some sort of pre-production model for evaluation or so.
It has a tag that reads: AVQ-9 No1, Supplied by James S. Spivey. The
connectors on the front are, AC input, Indicator, RX antenna, TX
antenna. In the documentation the AN/AVQ-9 is some laser aiming system
on a Phantom and this is definitely an Altimeter.
There is also a reversible tag on the set that reads: Set is wired for
115V. On the back of this tag it reads: Set is wired for 80V.  I was
told that 80 Volt was in use on WW2 British planes. The TX output valve
is a 6J6 that is frequency adjusted by a strip line, the same for the RX
input circuit. In it is a big DC-22-A crystal unit dated 1943 with a
frequency of 98.356 KHz
Because it is serial number 1 I guess this was some test model and the
Sets ID was later changed. Does it ring a bell to anyone?
This is not my line of collecting but it intrigued me because of the
serial No 1 , is there a dedicated user group on this kind of aircraft
instruments to see if anyone is interested in it? Indicator and set are
in good condition.

Thanks, Nico  PA3ESA