[EMAIL PROTECTED] made an utterance to the drakelist gang ---------------------------------------------------------------------- On Thu, 12 Jan 2006, Karl Henrik Laache wrote:
> I'm not sure, but I think there is a difference between the chimneys for > the 3-400 and 3-500 tubes. The 500s are slightly higher than the 400s, > and the chimneys for the 500s don't have the tapering at the top, where > the chimneys for the 500s are cylindrical. 3-400Z chimneys are a half inch shorter than 3-500Z chimneys. I have a pair of 3-400Z chimneys for sale, btw. Anyone interested, please email me - I can send photos when I get home after work. Eimac 3-400Z and 3-500Z chimneys have the tapered top to provide airflow over the anode seal and heat dissipator. 3rd party chimneys have a relatively small taper and don't do such a good job to cool the anode seal. Coleman lantern glass is cylindrical (has no tapered top) and is useless to protect the anode seal. Glass chimneys sold by Ameritron for 3-500Z tubes will not work with 3-400Z tubes in the Drake L-4 - they're too tall. You can get a rough idea of the form factor of the SK-416 inside my L4 by viewing these links: http://n1su.com/tubes/3-400Z-idle.jpg http://n1su.com/tubes/3-400Z-bias.JPG As discussed at length on the Amps mailing list, the chimney system used in the Drake L-4/L-4B does a poor job of protecting tube life - the only way to improve it without major modifications is to replace the stock fan with one that provides increased air flow - but the bottom line is it still doesn't provide a safe environment for exceeding the original design: 1000W input for CW and 2000W input for SSB. -- 73 Jason N1SU http://n1su.com/ ---------------------------------------------------------------------- Submissions: drakelist@www.zerobeat.net Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net ----------------------------------------------------------------------
