I've been keying my TL 922 with a Mark V and haven't been using a keying
buffer. Do I have a problem just waiting to happen?
73,
Larry K4AB
On Sun, Nov 9, 2008 at 12:40 PM, Pete Smith <n4zr@contesting.com> wrote:
> My Mark 5 has one. My SB-220, though, now has a 300-volt FET to switch the
> vacuum relays.
>
> 73, Pete
>
> At 11:45 AM 11/9/2008, Carl wrote:
> >Most xcvrs havent used a relay in decades. SS doesnt like 120V @ 100 ma
> >
> >Carl
> >KM1H
> >
> >
> >----- Original Message -----
> >From: "Joe Subich, W4TV" <w4tv@subich.com>
> >To: <amps@contesting.com>
> >Sent: Sunday, November 09, 2008 10:20 AM
> >Subject: Re: [Amps] SB-220 saga continues
> >
> >
> > >
> > > The keying line (PTT relay) in the SB-220 is +120 V DC. The contacts
> > > of the "Linear" or "Send" relays in most transceivers can not handle
> > > the voltage and current "spike" generated by the high voltage PTT
> > > circuits in the older amplifiers (SB-200, SB-220, L4, L7, TL-922,
> > > etc.).
> > > You will probably need to replace the "Linear" or "Send" relay in your
> > > transceiver (if you are lucky, that will be all).
> > >
> > > I suggest adding a keying buffer (e.g. Ameritron ARB-704), modifying
> > > the SB-200 with the internal Harbach Electronics soft key circuit
> > > (www.harbachelectronics.com/main/page_products_sb220__sb221.html),
> > > or converting the SB-200 to faster, low voltage relays and electronic
> > > bias switching.
> > >
> > > 73,
> > >
> > > ... Joe, W4TV
> > >
> > >
> > >
> > >> -----Original Message-----
> > >> From: amps-bounces@contesting.com
> > >> [mailto:amps-bounces@contesting.com] On Behalf Of Roger (K8RI)
> > >> Sent: Sunday, November 09, 2008 12:34 AM
> > >> To: ke1fo@arrl.net
> > >> Cc: amps@contesting.com
> > >> Subject: Re: [Amps] SB-220 saga continues
> > >>
> > >>
> > >> Please do not cross post between reflectors.
> > >>
> > >> Roger (K8RI)
> > >>
> > >> Alfred Frugoli wrote:
> > >> > Hello everyone,
> > >> >
> > >> > So it seems I've got a problem with my SB-220.
> > >> >
> > >> > When the amp is off, but connected in the RF path,
> > >> everything is fine.
> > >> >
> > >> > When I switch the amp on I've suddenly got lots of attenuation
> > >> > happening on the receive path. Transmit seems fine - amp tunes OK
> > >> > etc.
> > >> >
> > >> > My first suspicion was that there were dirty relay contacts on the
> > >> > receive side. Cleaned the contacts with no success. Then
> > >> I realized
> > >> > that the problem only occurs when the amp is on. So a trip to the
> > >> > schematic tells me I don't understand. In the RX mode the RF path
> > >> > through the amplifier should be the same as when the power
> > >> is on. So
> > >> > I'm not sure where my attenuation is coming from.
> > >> >
> > >> > Just testing it a few minutes ago I can make an S5-7 station almost
> > >> > completely disappear by turning on the amp, so I've got
> > >> somewhere in
> > >> > the area of 20db of attenuation happening!
> > >> >
> > >> > Thoughts?
> > >> >
> > >> > Thanks.
> > >> >
> > >> > 73 de Al, KE1FO
> > >> >
> > >> > -----
> > >> > Visit my amateur radio contesting blog at ke1fo.wordpress.com.
> > >> > _______________________________________________
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> > >> >
> > >> >
> > >>
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