"Gerry" <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- You hit the nail right on the head as to why manufacturers chose sweep tubes over transmitting tubes back in the old days. It's all about cost. Lower manufacturing cost equals higher profit margins. As to the comment made about plate dissipation ratings, that figure is for continuous duty. In SSB service, which is what most rigs of the time were intended for, you can safely exceed that value because SSB is intermittent service. What the word "safely" meant was always up to conjecture. It was always planned that at some future date, the finals would eventually go soft and you would have to replace them. But as pointed out, sweep tubes were cheap and plentiful so that was no problem. I think it must be astonishing for the original designers to see their designs still functioning some 20, 30, or 40 years after the product was discontinued! I know sweep tubes get hot but I can honestly say I have never seen the 6JB6's glow red. I have seen this in Swan rigs which had plate voltages over 750 volts. In fact the 1200X linear with 4 6950's ran the plates at 900 volts! My T-4XC still has the same finals I've had for the past 10 years and still shows full output on 10 meters. Though there was no fan in the original design, I have always used one on my Drakes. The main difference between sweep tubes and transmitting tubes is the type of glass envelope used. Transmitting tubes have higher temperature rated glass so if you can cool the glass envelope of your sweep tubes, they will last longer.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael Tallent Sent: Wednesday, July 07, 2004 12:40 PM To: [EMAIL PROTECTED] Subject: Re: [drakelist] Sweep tube's to 6146's Michael Tallent <[EMAIL PROTECTED]> made an utterence to the drakelist gang ---------------------------------------------------------------------- Becaus in the glory days of vacuum tube TV sets the sweep tubes were very cheap and available at the corner Drug Store, 6146's were transmitting tubes and cost more at that time. Now vacuum TV sets are gone, the sweep tubes have very little other uses and 6146's are still transmitting tubes. At that time most hams were happy to have the $1 sweep tubes instead of the $3.00 6146's. Mike Tallent W6MXV designed color TV stuff in the 1960's at RCA ----- Original Message ----- From: "PWells" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, July 07, 2004 10:18 AM Subject: [drakelist] Sweep tube's to 6146's > > PWells <[EMAIL PROTECTED]> made an utterence to the drakelist gang > ---------------------------------------------------------------------- > Peter > I thunk that you have made the right decision on converting to 6146's . > I plan to de the same wiyh a couple of Yaesu's that I love. > Hey, operating is what it's all about. We are first and foremost hams, > not antique dealers. I also agree that it was a mistake and also a bit > of a mystery as to why so many transceivers were made with sweep tubes. > Kenwood was the first to wake up with their TS 520/820 series and them > Yaesu caught on with the FT-101 ZD. I might even have to convert my TR-4 > one day! > > 73's > VE2FAR > ---------------------------------------------------------------------- On Behalf of Michael Tallent <[EMAIL PROTECTED]> Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ---------------------------------------------------------------------- ---------------------------------------------------------------------- On Behalf of "Gerry" <[EMAIL PROTECTED]> Submissions: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Zerobeat Web Page: http://www.zerobeat.net Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ----------------------------------------------------------------------
