[Amps] SB-220 saga continues

[Bob Maser]

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.
>> > >> > _______________________________________________
>> > >> > Amps mailing list
>> > >> > Amps at contesting.com
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>> > >> >
>> > >> >
>> > >>
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