Hello Mike:
Well, the 20 feet or so of RG 8 will not cause any loss of receiver
sensitivity, while eliminating power roll off of the exciter. It is a
pretty simple solution to a very common issue with transistor exciters
driving amplifiers.
73,
Mike Schatzberg
WB2AJI
----- Original Message -----
From: "m.ford" <k1ern@direcway.com>
To: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>
Cc: <amps@contesting.com>
Sent: Saturday, October 08, 2005 10:31 PM
Subject: Re: [Amps] TT Centuruion oscillation
>
> ----- Original Message -----
> From: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>
> To: "Henry Pfizenmayer" <pfizenmayer@worldnet.att.net>
> Cc: <amps@contesting.com>
> Sent: Saturday, October 08, 2005 6:03 PM
> Subject: Re: [Amps] TT Centuruion oscillation
>
>
> > Hello Henry:
> >
> > If you remove the coax from the Orion, while it is oscillating, does the
> > oscillation stop?
> >
> > Are you using the tuner, if yours is so equipped, in the Orion when the
unit
> > oscillates?
> >
> > If you are using the tuner, try turning the tuner off. If you have no
> > tuner, you might try inserting one between the Orion and the Amp.
> >
> > You may have a ground loop on 40 that might be causing some issues. You
> > might try a longer length of coax between the Orion and the Amp, say
about
> > 20 feet of RG 8 type.
> >
> > Also, it is worth trying a line isolator to help with the ground loop if
one
> > is present. I have an extra one if you want to try and see if it will
help.
> > They are not very expensive in any event. Place the line isolator
between
> > the Orion and the Amp.
> >
> > When you add the longer coax, see if the input SWR does not indeed
improve
> > from the 1.4:1 which you have now.
>
> When you add longer coax you increase the return loss thus improving the
SWR.
> If you add enough coax you can drive the return loss so high that you
appear to
> have a nearly perfect match no matter what is connected to the other end.
>
> Of course you wouldn't hear anything either.
>
> Mike k1ern
>
> >
> > 73 and Happy Dxing,
> >
> > Mike Schatzberg
> > WB2AJI
> > ----- Original Message -----
> > From: "Henry Pfizenmayer" <pfizenmayer@worldnet.att.net>
> > To: <amps@contesting.com>
> > Sent: Saturday, October 08, 2005 10:58 AM
> > Subject: Re: [Amps] TT Centuruion oscillation
> >
> >
> >> By any chance has anyone experienced self oscillation with a Centurion
> > key
> >> up after application and removal of drive ? Mine has decided to do this
on
> >> 40 meters only (into a good 50 ohm dummy load). It is fine on all other
> >> bands. On 40 it appears to tune normally and have normal power out but
key
> >> up it continues to put out about 250 watts PF and PR on the internal
meter
> >> (nothing is coming out of the amp because the TR relay is in
receive.)
> >> Have not determined the freq of oscillation as of right now. Input SWR
> > seems
> >> about normal 1.4 worst case on 40 .
> >>
> >> Once its oscillating - makes no difference if its in operate or
standby .
> >> You can kill it by pulling the key lines - or by turning the Orion off.
> > (no-
> >> the Orion is not putting out power key up - and have tried changing the
> > qsk
> >> delays)
> >>
> >> Using Orion driver - have tried changing to ant 2 and keying loop 2 -
no
> >> difference. Orion seems perfectly normal in all respects. (output power
> > does
> >> not hang on any band )
> >>
> >> Have checked the Centurion input filter band switching voltage to the
lpf
> >> board and it is switching ok. Have the lpf board out , all solder
> >> connections look fine , 40 meter filter has continuity - will check
the
> >> relay tomorrow .
> >>
> >> Just wonder if anyone has seen this . TT has not seen this and I have
> > tried
> >> several things they suggested on a couple different calls.
> >>
> >> Rgds-- Hank K7HP
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|