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## [TowerTalk] Top Hat Switch

 To: [TowerTalk] Top Hat Switch richard@karlquist.com (Richard Karlquist) Wed, 18 Jul 2001 22:16:25 -0700
 ```Tom brings up some valid points. I have been using a 90 foot vertical with a top hat for several years. It has latching vacuum relays at the 30 and 60 foot levels, so that I can make it look like a 30 foot vertical for 40, a 60 foot vertical for 80, and a top loaded 90 foot vertical for 160. The voltage across these relays is brutal, as Tom correctly points out. I have had some reliability problems. I think that I really should pot the relays because the terminals are too close together when condensation occurs, which seems to be optimum when I am trying to work 75M long path in the morning. I am planning to rebuild the vertical, and I am thinking now of using pneumatically operated knife switches or something. This eliminates the problem of getting DC current up to the relays. I am thinking about looking into the actuators that are used in cars to open and close air conditioning vents. If anyone has any bright ideas along these lines, I would be interested in hearing about them. Previously, I had the same vertical without relays. On 80 meters, I simply fed the whole thing as a voltage fed antenna. Worked just fine. For 40, I just put up a separate little 30 foot vertical elsewhere. Details of the antenna are on my web site: www.karlquist.com Rick Karlquist N6RK -----Original Message----- From: owner-towertalk@contesting.com [mailto:owner-towertalk@contesting.com]On Behalf Of Tom Rauch Sent: Monday, July 16, 2001 5:54 PM To: towertalk@contesting.com; Ford Peterson Subject: Re: [TowerTalk] Top Hat Switch You are begging for problems. The relay is at a voltage point, and worse yet you have a vertical! The voltage can be as much as twice the voltage on a dipole at the end, assuming you have a good ground system. That means you could have the equal of what a dipole would do with 6 kW applied power!! I did this quickly using a 2" diameter vertical, and there was about 3 kV RMS with 2 kW of applied power. That's over 4kV peak voltage, that you'd have to handle in all kinds of weather. You're talking HV vacuum latching relays, which use a very high pull-in current. You have to be sure the path across any insulation, when wet, would remain open. 73, Tom W8JI W8JI@contesting.com List Sponsor: Are you thinking about installing a tower this summer? Call us for information on our fabulous Trylon Titan self-supporting towers - up to 96-feet for less than \$2000! at 888-833-3104 www.ChampionRadio.com ----- FAQ on WWW: http://www.contesting.com/FAQ/towertalk Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com ```
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