[Amps] SB-220 saga continues (correction)

[Pete Smith]

Sorry, the second set of numbers should have been VAC.

73, Pete

At 04:30 PM 11/9/2008, Pete Smith wrote:
>With the relay enabled, the specs say the Mk5 can switch up to 60 VDC at up
>to 200 ma, or up to 100 VDC at up to 500 ma.  I *think* the TL-922 has a
>low VDC switching circuit, because the manual on my TS-930 says it can
>switch that amp with the transistor switch that is provided for QSK.  Other
>older amps with higher-voltage relay circuits are another story, of course.
>
>73, Pete N4ZR
>
>, Bob Maser wrote:
> >Hi Larry.  Why do you put an ammeter in series with the center conductor of
> >the key line and see how much current it is drawing when in the transmit
> >condition.  I would guess it would be somewhere around 100 to 150ma @ 26V,
> >which I think the Mark V can handle all day long. I don't know what the MkV
> >rating is but my FT1000D is good for 2A @ 30VDC!
> >
> >Bob  W6TR
> >----- Original Message -----
> >From: "Larry K4AB" <larry.k4ab at gmail.com>
> >To: <amps at contesting.com>
> >Sent: Sunday, November 09, 2008 8:24 PM
> >Subject: Re: [Amps] SB-220 saga continues
> >
> >
> > > 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 at 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 at subich.com>
> > >> >To: <amps at 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 at contesting.com
> > >> > >> [mailto:amps-bounces at contesting.com] On Behalf Of Roger (K8RI)
> > >> > >> Sent: Sunday, November 09, 2008 12:34 AM
> > >> > >> To: ke1fo at arrl.net
> > >> > >> Cc: amps at 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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