Hi Mark,
Nobody told me anything, I make my own measurements on relays and switches
using a network analyzer.
My comments about poor performance specifically related to VHF-UHF, not HF.
I use a c. 1935 copper bladed knife switch to switch 450 Ohm ladder line and
it has zero loss at HF -- also a perfect impedance match, since the blade
spacing is exactly right to make a 450 Ohm balanced line with an air
dielectric.
Most homebrew/relay switches start going to pot at about two meters (144
MHz) and really start to stink at 70cm (432 MHz).
WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: Mark [SMTP:aa6dx@pacbell.net]
> Sent: Tuesday, February 04, 2003 7:37 PM
> To: Steve Katz; 'KG4QDZ'; towertalk@contesting.com
> Subject: Re: [TowerTalk] Remote Antenna Switches
>
> Hmmm, -- who told you that? I have a home-brew I bought from an old-timer
> a
> year ago or so, and it works swell! I've swept it's frequency w/ MFJ 259
> ..
> and put in/out into dummy ... NO loss detected, no impedance bumps I can
> discern on 80 through 10 .. (I am sure there are some, always is, but ..
> NOT
> apparent .. soooooo?) Has super duper professional relays .. I will have
> to
> dig up the original info if I can find it, and .. it is fed 12 V up the
> feedline, which I did not like .. but, guess what .. worky worky, stick
> 1500
> watts there, and it dobedo just fine... NOT made out of junque, simply the
> best of home-brew... 73 --- Mark AA6DX
> Original Message -----
> From: "Steve Katz" <stevek@jmr.com>
> To: "'KG4QDZ'" <kg4qdz@arrl.net>; <towertalk@contesting.com>
> Sent: Tuesday, February 04, 2003 11:01 AM
> Subject: RE: [TowerTalk] Remote Antenna Switches
>
>
> > 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
>
>
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