radiotechnician wrote:
I read the IRE references, and are convinced they used 24-A (224) tubes,
not 235. They were doing some groundbreaking work then. I don't think
it was realized that those tubes could operate at 60 mHz.
The internal document from the lead engineer describes the chassis as having "one 227, six 224's and two pentodes". All six of the 224's are specifically called out, first detector, 1st IF, second detector, 1st amp, sync amp and picture amp. The only tubes not specified are the 2nd and 3rd IF's. This coupled with the extra contacts on those two, and only those two sockets verifies them as space charge pentodes. Unfortunately no other mention of the tubes has been found.
Looking at the specs for the P1, this is no doubt the type of tube used here.
radiotechnician wrote:
The tetrode circuits would have to work well outside the dynatron kink
zones for the tubes. Had they used 235 tubes, they would mentioned what
transconductance they chose, and perhaps if it varied, how the IF response
curve would change.
For whatever reason they actually used the negative resistance of the 224's for the scan oscillators which makes no sense as the lab work prior to this set used gas thyratrons and the the field test sets after this one used blocking oscillators. Why in heck did they use finicky dynatrons oscillators?
radiotechnician wrote:
As is, the paper has an error in one of the graphs, megahertz instead of kilohertz
Nothing in that setup could have worked at 400 mHz.
I never noticed this. Which graph was this? (Maybe someone was really optimistic about the performance

)