[amsat-bb] Re: Easy to make, low cost omni-directional antennae

[Bruce Robertson]

On Thu, Mar 27, 2008 at 4:17 PM, Bill Dzurilla <billdz.geo at yahoo.com> wrote:

>  If you do go omni, get it high enough to be in the
>  clear.  And unless you get a preamp, use very good
>  coax and keep the line as short as possible.  You can
>  get a 70cm receive-only preamp from Ramsey Electronics
>  for $17, but with that you'll need a separate coax
>  line for the 2m uplink, or a duplexer.

You can get such a preamp from Ramsey, but as one who has built their
preamps in hopes that they will suffice for satellite operations, I do
not recommend it. Remember that the improvement that a preamp makes
(for a given position in the receiving system) is related to the gain
and inversely to the noise figure. Gain is easy, low noise figure is
not; but without the latter you will receive more noise on 70cm, not
more signal. I would strongly recommend a ARR or SSBUSA preamp for any
beginner. Since the marginal expense is not that great, you are much
better off getting a switching model appropriate for out-of-doors use.
Get switching also because you will want to diversify into mode-B
operations, using VO-52 in particular.

I have enjoyed many Ramsey kits in the past, but my experience is that
their preamps are not designed for improving weak-signal reception on
either the VHF or UHF satellite bands.

73, Bruce
VE9QRP