Most DC relays without indication of "+/-" polarity are non-polarized. For
QSK operation, it may be best to add your own snubbing diodes to all relays,
including the vacuum relays. It may also be helpful to review the following
discussion concerning the use of relay snubbing diodes:
http://www.cliftonlaboratories.com/diode_turn-on_time.htm
Paul, W9AC
## I use a 1N5408 across the coil of my vac relays. Some of the vac
relays I use have 26.5 vdc coils, some have 12 vdc coils. All get a 1N5408
## To INCREASE the RLS time of a vac relay...[faster rls]... that uses a
diode
for back emf suppression... insert a 2-3 W MOF resistor in series with the
snubber
diode.
Use a value of 200-300 ohms. Resistor can go on ether side of the diode of
course, as both the diode and resistor are in series. This technique is not
described
in the above url that Paul posted.
## The diode + resistor combo is used on the INPUT vac relay...[ + bias relay].
The OUTPUT vac relay gets JUST the diode only !
## End result is [ with ALL 3 x relays sped up] all 3 x will operate <1.8
msec.
The OUTPUT relay will RLS dead last.
The bias relay the fellow wants to use does not look like a reed relay to me..
dunno.
In any event, the AUX contacts on it are only rated for 28 vdc !! You will
destroy
them, if using + 120vdc for switching cut off bias. +120 vdcv for cut off
bias is
dinosaur technology. Better to simply use a 100 K 3 watt MOF in the CT of
the
fil xfmr.. and short the same 100 k R out with the contacts of the bias
relay.
Only a spst relay is required for this.
On another note. He is using 2 x vac relays + 3rd relay... with all their
coils in series, plus
a shunting resistor across the bias relay coil. This will work with +120
vdc.. and
speed all 3 x of em up.
On the 2 x GS35B 6m amp, I helped a friend with... we used 3 x Gigavac
GH-1's
[like a rj1a] one for input, one for output, 3rd one for the bias [ shorts
out the 100k R]
All of em have 12 vdc coils. All are very easy to speed up with an
overvoltage.. and just one
series dropping resistor. If u want to speed em up even faster, install a 50
uf lytic across
the dropping resistor. Then u end up with a 'RC hotshot speed up circuit' .
On the 6m amp.. both GH-1's mounted side by side, with 2 x SO-239's above them.
Bypass swr on 6m is dead flat.
For his proposal, I would deep 6 the idea of using +120 vdc for cut off
bias.. and
use the 100k R in the CT of fil xfmr. We always use 2 x 100 K in
parallel,,, for
redundancy.
later... Jim VE7RF
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