(Choice) 50's Vintage PHILCO UHF Converter, UT-20, UT-21, UT-21D

Description

You can now have your very own piece of early television history!!
These UHF converter units were left behind in my late father's electronics inventory.   He was a radio and television serviceman for much of his life, beginning right after WWII.   He must have stocked up on this inventory as the UHF channels opened up!   My husband did a bit of research to see exactly what these units were.   Here's a bit of what he found:
THE BIG FREEZE
:  By 1948, the US had about 50 television stations broadcasting on VHF.   By September 30 that year, the FCC had granted 110 licenses.   With additional applications in the 100s, the FCC instituted a "freeze" on new TV licenses.   At that time, the industry was overwhelmed by technical issues, which required careful study.   One of those issues was the need for a wider broadcast spectrum, which would require the allocation of UHF bands.
UHF RESEARCH
:   During the "freeze," the FCC licensed an experimental station for UHF broadcasting, located near Bridgeport, Connecticut.  In Dec., 1949, they began 2 years as a national resource for research.
THE BIG THAW
:   On April 14, 1952, the FCC resumed granting new licenses, including the new UHF frequencies.  By Sept, station KPTV in Portland, Oregon became the first commercial TV station to begin UHF broadcasting.     Manufacturers flooded Portland with UHF receivers and UHF conversion kits for existing VHF televisions, ushering in a new era of UHF broadcasting.
PHILCO CORP. FIELD TESTS
:   By 1953, PHILCO was marketing its TV-90 chassis with UHF reception.  On April 23, 1953, PHILCO conducted a TV field test of a 2-month old station in Roanoke, Virginia.  For their field test of Channel 27 UHF transmissions, PHILCO engineers used a 1953 PHILCO TV set with a 90-chassis.
THESE PHILCO UHF UNITS
:   These UHF receivers were designed for the 1953 TV-90 chassis--  the same chassis which PHILCO engineers used in the Roanoke field test in April, 1953.   An now you can own this museum-quality piece of television history!!
Apparently the first conversion kit was the UT21.   After 4 runs, PHILCO changed the part number to UT20.  It would seem that the UT20 is a re-designed and improved unit.   Since our unit was found in a shipping box, not a Philco box, with an exact fit for it, it would appear that it is a replacement part, and not a conversion "kit."   You decide from the photos.
The UT-21 units were designed to be installed to adapt the VHF PHILCO TV-90 series televisions to receive UHF.   What a piece of TV history!!
Installing one of these in your vintage PHILCO set would be like putting a hood ornament on your classic restored car!   (I don't have a photo of the factory sealed box.   Same photos as the opened box.)
The UT-21 is part number 43-6475, and the UT-21D's part number is 43-6778.   I'm not certain what models the UT-21D fits.  The UT-20 unit is no longer in the original box, and has been separated from the accessories package.
Other numbers on the unit are:   2733215,  76-7595,  6AF4 UHF OSC,  TPT-416.    My Dad wrote this on the box:   40 MC F1 Output.
That one is sold for parts only, or for display.    None have been tested, and are sold as is, as found.
The UT-20 and UT-21 are designed for chassis type '53 line TV-90 series.   Specific models are on Sam's Photofact index, May-June, 1953, p. 26 & 27, and also reprinted on the "americanradiohistory.com site, entitled "The following is a list of models which will accommodate the...".   Look for them on a Google search.
What fun displaying these, or even just "playing" with them to see the early TV technology near 70 years ago!!
Thanks for looking (and reading through all of this!).
(radio shelves)