[Amps] Re: QSK-5 Relays and PINs

Jim Reid jimr.reid at verizon.net
Sat Jan 25 10:11:32 EST 2003

Hi Bob,  you wrote,  in part:

>  I also have an AL1500 and an external QSK5.   As far as I 
> can tell (I actually have not used it much) my QSK5 is loaded 
> with PIN diodes but has no relays.  Are you saying it does 
> have a relay in it.........

Yes,  the unit has two relay assemblies.  One is a small,
sealed gadget,  probably a reed relay.  This unit, called RLY1
by Ameritron in their manual circuit diagram,  pgs 7 and 8,
is activated by a short to gnd.  into the Key 1 connector of
the QSK-5.  The RLY1 relay,  when not activated connects the
transceiver directly to the amplifier input terminal.  When active,
the relay switches the transceiver into the PIN diode switching
strings to which you refer in your note;  this occurs when a
PTT or Key down is sensed at the Key 1 input terminal of
the QSK5.  

The second,  large,  open frame relay,  Ameritron labels as just
RLY in the diagram; it is a three pole,  double throw on each pole.
When not activated,  the output terminal of the amplifier is
connected directly to your rig antenna system.  Thus with the
QSK5 not operating,  and with no signal into the units Key 1
and Key 2 terminals,  the QSK5 PIN diodes are completely
out of use,  and the transceiver is in RCV mode with the antenna
system "seem" by the xcvr directly through the "by-pass"
line of the external amplifier.  This open frame relay is also
active when Key 1 is activated.

When Key 1 is activated,  the amplifier T/R relays are activated
and the amp is set to transmit and if the xcvr is to recieve an
input signal from the antenna system,  it receives it via the
PIN diode switches within the QSK-5.  However,  when Key 2
of the QSK5 is activated, the rcv PIN diodes are blocked OFF,
and the transmit PINs become active allowing the rig system
to transmit.  

So,  the QSK5 has two sets of PIN diodes,  a set for rcv and a 
set for xmit,  AND two mechanical relays which,  in effect,
add or remove the QSK5 PIN diodes and biasing circuitry
completely from your rig system.  If the power is OFF to the
QSK5 unit,  the mechanical relays,  in their "relaxed" positions,
have the xcvr,  amp and antenna system all connected together
just as they would be were no QSK5 unit there at all.  And,
your system "returns" to this configuration after a 3 to 5
second time constant after key-up with no subsequent
key closure in the CW mode.  While you are sailing along
in CW transmit/QSK rcv,  the mechanical relays are held
active (closed)  and the two PIN diode strings in the QSK5 unit
are doing ALL the T/R switching for your system.

My set up is to connect the key/ptt line directly to
the  "Key 1" input of the QSK-5, and the "External T/R" output
on the back of the transceiver is connected to the "Key 2" input of
the QSK-5. I make NO connection to the QSK-5 AUX socket,  
no need (it is sort of an "after the fact" output signal that now the 
QSK-5 switch is activated,  I could not find  a use for it,  hi). 

Why this way--To quote a couple lines from the -5 manual:

" The transceiver MUST have the proper sequencing of the  RF and
QSK output lines.  The transceiver QSK line must pull low BEFORE
RF appears on the output connector and release AFTER the RF
envelope reaches zero to operate with any QSK switch."

Note,  in Ameritron's language,  "QSK line" = the T/R relay
output from your transceiver.

Also,  it seems the Key 1 input jack must go low immediately with
key down as this is what closes the linear amp relays.  A "ground"
input signal to Key 2 is what changes the diode gates from
rcv to xmit,  and THEN AUX is pulled low;  so I reasoned that
my xcvr amplifier T/R relay line was just the ticket to go to the
QSK5 Key 2 input terminal.  Works just great!

Hope all this helps,  Bob,  and you now see the uses for both
the PIN strings and the mechanical relays in the QSK-5.

73,  Jim  KH7M

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