BulbCollector Forums

VACUUM TUBE COLLECTING => Tube Discussion => Topic started by: Tedd on January 13, 2006, 12:01:40 am

Title: Age of Blue or Red Glass Seals in Geissler & Crookes Tubes?
Post by: Tedd on January 13, 2006, 12:01:40 am
I'm interested in ways to estimate the age of Geissler and Crookes tubes, and lately I've been wondering about the blue and red glass seals I've seen in some. ?I have tubes like each of these examples:

1. external wire loops (no terminal caps) with blue glass inside to seal the feed-thru wire to the internal electrode.

2. small dome-shape terminal caps with red glass inside to seal the feed-thru wire to the internal electrode.

Does anyone have information on when each of these colored glass seals was used (approx. start and end dates)? ?Is there any specific reference material you can point me to?

Thanks in advance for any info!

Tedd