Sorry for the confusion... Maybe I wasn't very clear on my post. First
of all, my Micor is a repeater station, unified chassis.
I performed this mod:
For the Transmit Exciter, you have a choice:
1.) To enable the exciter all the time, connect pin 19 to pin 20 on
the top row of 30 {transmitter} interconnect board pins that come
through the backplane. These are the 3 sets of 10 pins sticking
through the backplane board on the top. Pin 19 is F1 channel element
select and pin 20 is ground.
2.) For those who don't care to have the transmitter oscillator
running all the time, you can use the (switched ground) logic provided
by the Station Control Card that was originally intended to drive the
antenna change-over relay to key the exciter channel element during
PTT. The Station Control Module Modification explains how to do this.
Ensure that you place the transmit and receive channel elements into
their respective F1 positions.
SO NO, the exciter itself is not on until the repeater is keyed up..
I have a bird & dummy load on the exciter (no PA) and I have about 2.5
Watts out when the repeater is keyed up. BUT with the mod in place, I
have no power out to the bird, but do have a signal (which I'm calling
the oscillator). Is this mod just for the base station and not the
repeater station? I don't see any performance difference with the mod
in or out. (other than the signal floating around :) )
Thanks everyone,
Jordan
--- In Repeater-Builder@yahoogroups.com, "Milt" <[EMAIL PROTECTED]> wrote:
>
> The exciter should NEVER be run full time.
>
> A Micor exciter will develop 400 milliwatts, that's 0.4 watts and
that much
> loose RF running around loose in the station is asking for trouble.
>
> Running the channel element full time is often done, but not a good
idea,
> it's much better to switch the channel element on as needed. The
use of the
> antenna switch transistor on the station control module as shown on
repeater
> builder is an excellant idea.
>
> Milt
> N3LTQ
>
> ----- Original Message -----
> From: "Bob M." <[EMAIL PROTECTED]>
> To: <Repeater-Builder@yahoogroups.com>
> Sent: Wednesday, May 30, 2007 6:41 AM
> Subject: RE: [Repeater-Builder] Micor oscillator mod question
>
>
> > No one has answered his original question, that is:
> >
> > What benefit does he get by wiring the exciter to be
> > ON all the time?
> >
> > I think he's discovered one of the non-benefits and is
> > trying to figure out if the leakage he's experiencing
> > is worth the effort. Even a well-shielded and filtered
> > repeater station will leak something.
> >
> > Personally, I think I'd only keep just the oscillator
> > running all the time, not the entire exciter. The only
> > reason I can think of doing this is if the oscillator
> > is slow to come up to frequency when the station is
> > keyed. I would expect it to take only milliseconds for
> > stability to occur, so there really shouldn't be any
> > noticeable benefit. The exciter is putting out a whole
> > lot more RF power than the oscillator. Perhaps this is
> > really what he's done, or should do.
> >
> > Bob M.
> > ======
> > --- Eric Lemmon <[EMAIL PROTECTED]> wrote:
> >
> >> Jordan,
> >>
> >> Assuming your Micor station has a unified chassis,
> >> was it always a repeater,
> >> or was it converted to repeater use from a base
> >> station? Repeater stations
> >> have a great deal of extra filtering in the
> >> interconnect boards that connect
> >> the RX and TX shelves to the backplane. The
> >> repeater chassis also is
> >> equipped with extra shield plates that cover the RX
> >> and TX shelves, which
> >> plates should be secured with all screws in place.
> >> The purpose of the extra
> >> filtering and shielding is to prevent (or greatly
> >> attenuate) any direct
> >> radiation from the exciter oscillator or the RX
> >> injection oscillator.
> >>
> >> 73, Eric Lemmon WB6FLY
> >>
> >>
> >> -----Original Message-----
> >> From: Repeater-Builder@yahoogroups.com
> >> [mailto:[EMAIL PROTECTED] On Behalf
> >> Of twoway_tech
> >> Sent: Monday, May 28, 2007 9:15 PM
> >> To: Repeater-Builder@yahoogroups.com
> >> Subject: [Repeater-Builder] Micor oscillator mod
> >> question
> >>
> >> I just modified my micor UHF for the exciter to be
> >> on all of the time.
> >> I am not for sure that I really like this mod. The
> >> oscillator signal
> >> seems to carry pretty far. Can someone tell me
> >> exactly what is gained
> >> by wiring the exciter to be on all of the time. Is
> >> it just for faster
> >> transmit response time?
> >> Thanks & I'm sure there will be more questions to
> >> come!
> >>
> >> Jordan, K9NZF
> >
> >
> >
> >
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