[Icom] ICOM rigs with other amplifier brands

[W3UIO]

Thanks Larry and others for some great info. That web
site in one post was excellent; however, all the
buffer circuits mentioned require external power. I
have built a circuit which was provided by ICOM
Technical Service which requires only one transistor,
one 1 K resistor, and one 1N4002 diode. The transistor
for the Alpha is 2SB834. Pop those into a little box
and no power need be provided. The transistors are
Japanese and hard to find. They can be had quickly
from Radio Shack Parts (order in store) or the parts
are all available from ICOM.

ICOM provided two circuits (one PNP and one NPN), and
two different transistors for each, depending on
whether the amp is keyed positively or negatively and
whether that keying voltage is <> 60 volts.

I have been using a Ten-Tec Omni VI Plus with a 20
year old Alpha 76 CA, and no buffer is needed. Now I
want to hook up my 706 plus pick up one of those high
filutin' 756 Pro 2's. I'm also going to upgrade my amp
to an Alpha 99. If I can get the ICOM provided
circuits scanned in a day or two, I'll post them here.
Several ICOM-with-amp friends have been using this
circuit for several years with no problems.

TNX AGN to all ES 73,

--- Larry Benko <benko@aztek-eng.com> wrote:
> Larry,
> 
> Many of the new amps such as Alpha 87 and 99 and the
> Acom
> 1000 and 2000 are fine to use without any buffer
> circuitry
> as they have buffer circuitry and only have open
> circuit
> voltages of 5 to 15V and short circuit currents of
> <10mA.
> Both the Acom and Alpha web sites provide specs.  I
> have
> driven an Alpha 87 and an Acom 1000 for more than
> 15,000
> qsos from a 756 PRO with no buffer circuitry. 
> However if
> you are not certain that the amp only requires a low
> voltage
> and current to key it then be certain to get a
> buffer relay.
> Also some buffer circuits will only drive amps that
> have
> a positive voltage (many old Heathkits had an AC
> voltage).
> Also some of the buffer relays may not operate fast
> enough
> (the 756 operates the send jack 9 to 10 ms. before
> the RF)
> to guarantee that the amp does not hot switch which
> would
> burn up the amp output relay and generate huge
> amounts of
> RF splatter.  Tell us what amp you are planning on
> using
> and someone her probably has experience with it.
> 
> 73,
> Larry, W0QE

=====
Larry, W3UIO

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