[TowerTalk] Remote Antenna Switches

[Steve Katz]

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 at pacbell.net]
> Sent:	Tuesday, February 04, 2003 7:37 PM
> To:	Steve Katz; 'KG4QDZ'; towertalk at 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 at jmr.com>
> To: "'KG4QDZ'" <kg4qdz at arrl.net>; <towertalk at 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 at arrl.net]
> > > Sent: Tuesday, February 04, 2003 9:46 AM
> > > To: towertalk at contesting.com
> > > Subject: Re: [TowerTalk] Remote Antenna Switches
> 
>