Homebrew switches using relays do not fare well at VHF, and less so at UHF.
Relay and wiring reactance takes over pretty quickly. Even using small form
factor relays interconnected by a good circuit board layout such as
Ameritron does, performance drops off pretty quickly above 144 MHz for the
"control line" version, and the "biased through the coax" version is worse.
For VHF-UHF remote antenna switching, I'd go with surplus Transco motorized
coaxial switches. Pretty much what everybody uses at VHF and above, most of
the Transcos are good to at least 2 GHz, some higher.
-WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: KG4QDZ [SMTP:kg4qdz@arrl.net]
> Sent: Tuesday, February 04, 2003 9:46 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Remote Antenna Switches
>
> I am trying to design something similar.
> Have you measured loss? How do you think these would do at VHF/ low UHF
> freqs? Has anyone tried these at higher freqs?
>
> 73 Skip (KG4QDZ)
>
>
> ----- Original Message ----- >
> > I made my own switch box. I used 10 amp Radio Shack relays. I have had
> one
> > relay burn up on me when I was having trouble with one of my mono
> banders,
> > and I burned the insulator on an SO-239 when the PL-259 barrell
> loosened.
> I
> > run 1500 watts cw & ssb, 160, 80, 40, 30, 20, 15 & 10, and the box has
> been
> > in service for 9 years. 1500 watts into 50 ohms will have about 5 1/2
> amps
> > of current.
> >
> > And the relays are very similar to the ones in an Ameritron relay box
> that
> > was given to me.
> >
> > As long as the spring contacts have sufficient power rating, a little
> follow
> > (wiping action) when the contact makes or breaks, and mounted so the
> relay
> > springs are vertical (so any dust will fall out), You should be able to
> use
> > just about anybodies box.
> >
> > de Paul, W8AEF
>
>
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