This may be obvious to some, but the cheapest cure to the switch problem is to install an ICL (inrush current limiter) in the hot lead of the power supply used. This not only protects the switch but also makes your tubes last longer. They are available from most of the major suppliers in a few brand names. (I use Ametherm). Just follow the rules in the application page on MFR site. It can be a bit confusing but use the minimum resistance type, you do not need a big super heater in there, they got hot.
Good luck and 73, Dick KF4NS St Petersburg, FL 33714 USA Keep The Glow! ---------------------------------------------------------------------- Message: 1 Date: Sun, 08 Jan 2012 23:14:10 -0500 From: Garey Barrell <[email protected]> To: Kris Merschrod <[email protected]> Cc: drakelist <[email protected]> Subject: Re: [Drakelist] Yet another AC-4 rebuild (now :-) completed Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Excellent job. The relay is certainly an effective way to protect that switch. However ... A simple power strip with enough outlets for a single station solves the AC switch problem. The key is to switch the equipment on -OR- off _only_ when the power strip switch is OFF. None of our boatanchor equipment has an easily power switch, most are on the back of a potentiometer. I don't use ANY boatanchor power switches 'hot' any more. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs <www.k4oah.com> Kris Merschrod wrote: > Mark, that is a nice description of the AC-4 rebuild. Thank you for sharing > it with us. > > I have done a few of them but using Mike's (Solar) approach. I confess that > I did not strip it > all down and scrube the chassis! Very good idea to use new bushing etc. > > I have gambled on the old switches holding out - so far so good. > > Kris KM2KM > ----- Original Message ----- From: "Mark Pilant" <[email protected]> > To: "drakelist" <[email protected]> > Sent: Sunday, January 08, 2012 11:05 AM > Subject: Re: [Drakelist] Yet another AC-4 rebuild (now :-) completed > > >> OK, now the rebuild is really complete. Yesterday I added the relay >> to take the load off the On/Off switch. Here are pictures and a >> description of what I did: >> >> http://www.n1vqw.net/ac4rebuild/#phase2 >> >> Before the addition of the relay, I measured a current draw of about >> 325 mA with the power supply unloaded. This would also be the current >> on the On/Off switch contacts. Since this was on an unloaded power >> supply, I would expect this to rise when transmitting. >> >> After the addition of the relay, this current (from the relay coil) >> seen by the switch contacts dropped to just a bit over 10 mA. This is >> a substantial drop, and should make the switch contacts last much >> longer. >> >> Oh yes, comments, corrections, and suggestions welcome. >> >> 73 >> >> - Mark N1VQW > ------------------------------ _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
