RCA UV-200 - Large plate detectors
The RCA 'Meatball' sticker is introduced
This time the cost cutting move was initiated to drop the RCA logo engraving from the tube envelopes.
A new sticker was applied to tubes, after production rather than during, and allowed the branding distinctions between Cunningham (C) logos and (RCA) logos to be moved downstream. Cunningham could now pick finished tubes, with blank bases and only the GE marks on it. It was then ink-stamped, got a sticker and voila! it was branded and ready to ship. Before this, any tube made with brandings engraved could not be substituted for one another to manage inventory.
Updates were made to drop the RCA logo etching on the envelope. This was replaced with the RCA 'meatball' sticker and simplified the cobranding efforts with Cunningham. Additionally, the GE logo was also no longer etched, but instead I believe it was applied with enamel paint. Many GE marks of this period are badly obscured. The example at left is a particularly good one.
RCA likely wanted to release the change to plate designs concurrently with the new envelope process. Retooling was expensive, and planned factory down-time unacceptable. Proving this isnt easy, but here is my evidence pushing strongly toward this conclusion. In reality however, simultaneous is never quite simultanous, and most variants come from this period of 'mix and match' assemby of different parts in different factories.
Plate vs Meatball sequencing evidence:
- No examples of uv-200 BBTT 'Meatball' variants have been found with 'winged plates', so plate changes preceded or coincided with the drop of the envelope engraving process (engraving <= plate)
- Prototype examples of new plate designs already use envelopes with lack of engravings, and enamel GE logo, further supporting that plate designs closely followed the engraving change. (engraving <= plate)
- An example of the (RCA) logo etching with the large smooth plate can be seen on uv201.com, so perhaps the assembly line was using up existing envelopes (plate <=engraving)
almost...simultaneously, there were new plate designs
Production probably started changing over to large plate design in May of 1923.
It was difficult to pin down this change, since the improvement did so little for the public, that the 'A' designator appears to have been dropped by everyone involved, instead, slipstreaming the changes into production as 'Model UV-200' tubes.
Planned to coincide, or not, developers in the Cuyahoga research labs were busily prototyping improvements to the 'winged' plate design. Plate designs were used for other tube types, such as the 201-A The approach of stamp-cuting four 'wings' to attach to supporting rods was tedious, and vibrations during oscillation often contributed to the 'howl' reported by users tuning their sets. Engineers experimented with stamping metal sheets to encapsulate the support rods. Tiny electric welds fused the crimps creating a much more stable and consistent result. It wouldnt be the last hand-work to be removed from the manufacturing process.
Small seamed-plate variants:
The introduction of 'pink' detector tubes
Pink tubes. Not just pink-ish, but deep pink throughout the envelope interiors.
Sometime after Aug 1922, the Cleveland plant began painting plate assemblies with a small amount of Phosporous amalgum. This resulted in a unique series of highly evacuated? detectors. I am unaware of any direct mention of the phenomena by RCA or General Electric, no have I found any attempt to market the pink tubes as superior.
I think making detectors was a problem for Cleveland, not because they couldnt produce quality tubes, but because they couldnt find the equivalent 'thoriated tungsten' breakthrough that they had done with amplifier tubes. So they experimented, a lot. Everything I have read suggests Cleveland was regularly 'on their own plan' when it came to tube production procedures.
-- research note: document references to argon use/detection here. Were are uv-200s Argon filled?
As we have seen in earlier variants of their work, they had already experimented with plate size, materials, and spacings between plate & grid. I suspect they 'slipped' many of their barely acceptable experiments into the production output.
In Jan 1922, when the Harrison plant opened, it was designated & setup for only magnesium getter use. Im further guessing, but at this point, experimentation in the Cleveland plant had probably made for some messes and batch contaminations.
Production demands were 3-5x higher for the 201 series tubes, and they burned out faster. Magnesium getters paired with thoriated tungsten was a big win and so Harrison was full steam making almost exclusively uv-201-a 'silvered' tubes.
So back at Cleveland, the pressure was finally off the uv-201 production lines, and they could 'fiddle' with the uv-200 production.
Using the Phosphorous amalgum that was about to be made obsolete, they 'painted' the outer two stem supports prior to assembly. During the evacuation and oven baking, a light, well-distributed getter was disbursed. I have seen slight variations in pink, but what makes this variant fascinating is that it was successful enough to span the transition from brass to bakelite base, and from tipped to tipless envelope.
- All examples of pink detectors have stem pressings marked 'H-14'
- All examples of pink detectors have large smooth plates
- Pink H-14 examples exist as: BBTT, BBNT, BKNT
- There are no pink examples with bakelite bases and tipped envelopes (these would have been WLCo. if existant)
- There are no pink examples with early (RC) style or
- There are no pink examples with WLCo. envelope etchings.
All of these details are clues to the origin, and rarity of these variants
Pink BBTT detectors were made after January 1922 in the Cleveland factory. It may be that the start date is much later. They were made until 15-Aug-1924 (max 30 months production)
Pink BKNT detectors were made after 1-Feb-1925 in the Cleveland factory. They were made until the switch to the UX base 15-Aug-1925, since they knew the UX-200-A was coming down the pipeline from Cuyahoga development. (max 6 months production)
Tipped large smooth-plate variants:
Tubes go topless
- tipless envelopes
- no more meatball stickers, though GE remains
- enameled RCA logo on envelope top
- new 'arched' style logo ink-stamped on brass base
UV-200 tipless large plate variants:
Tipless large smooth-plate variants: