> Paul Kelley <[EMAIL PROTECTED]> wrote:
> The length of the cavity (more importantly the inner
> conductor of the cavity) sets the frequency.
The size of the typical cavity center plunger is most
often used to "set the frequency".
The classic Motorola T-1500 UHF cavity becomes a vhf
cavity with a change of the plunger size (and probes -
loops). The internal center plunger length of travel
is similar to the UHF bottle.
> Usually cavities are designed to cover a RANGE
> of frequencies... the tuning rod coming out the
> top adjusts the length of the center conductor
> inside the cavity. The tuning range varies
> depending on manufacturer and model... some
> typical ranges are 136-150, 150-174, 136-174...
> and many others.
The requirements to get a vhf bottle down into the
ham bands can be an extra few inches of length,
which directly translates into cost (obvious).
You will often see "short vhf bottles" (cavities),
which don't go below 150 very far because they are
a lot cheaper to make for the higher range only.
> > 3. How awful a compromise would it be to use available
> > cavities from a 2 meter system at railroad frequencies
> > (160-161 MHz) ?
In many cases they would probably work just fine.
> If the cavities will tune that high, they probably work just
> fine. If the are now on the 2 meter band (below 148 MHz)
> they may or may not tune at 160 MHz... it depends on
> whether the center conductor can be adjusted that far by
> means of the tuning rod.
Yep
cheers,
skipp
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Repeater-Builder/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
