KXPA-100 to ICOM PW-1 amplifier

[George Rebong]

I used the RCA from the KX-3 to KXPA-100 adapter cable to connect the PW-1. I can not change transceiver selection on my PW-1 and the RX signal goes deaf/attenuated. Is there a setting that I can change to make my KXPA-100 key my PW-1?

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[Charlie T, K3ICH]

You better make sure you have a reliable ALC connection in there somewhere
because you'll smoke the PW-1 if you hit it with a hundred watts.  They
normally take about 35 -45 watts drive for full output.

Why not try driving the PW-1 directly with the KX3?  I did and it works
fine.  I don't get a KW out, but it's quite respectable power out with 12
watts drive.

73, Charlie k3ICH


----- Original Message -----
From: "George Rebong" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, July 29, 2014 3:25 PM
Subject: [Elecraft] KXPA-100 to ICOM PW-1 amplifier

>I used the RCA from the KX-3 to KXPA-100 adapter cable to connect the PW-1.
>I can not change transceiver selection on my PW-1 and the RX signal goes
>deaf/attenuated. Is there a setting that I can change to make my KXPA-100
>key my PW-1?
>
> Sent from my iPad 3G
> ______________________________________________________________
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[Josh Fiden]

Just to clarify... use of ALC with the PW-1 is not to adjust drive
power. That's a bad practice. You MUST use the ALC line because the amp
uses this as a primary means of protection. Without ALC, a fault
condition can damage the amp.

73,
Josh W6XU

On 7/29/2014 12:41 PM, Charlie T, K3ICH wrote:
> You better make sure you have a reliable ALC connection in there
> somewhere because you'll smoke the PW-1 if you hit it with a hundred
> watts.  They normally take about 35 -45 watts drive for full output.

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[Don Wilhelm-4]

Josh,

If one insists on using ALC for amplifier protection, set the level well
above that which will cause ALC to reduce the driving transceiver's
power during normal operation.

Most well designed amplifiers provide adequate self protection and
should not rely on ALC to reduce the drive in the case of a fault. If
the amplifier design relies soly on the use of ALC to provide fault
protections, I would call that 'risky design'.  If it is the primary
means of protection, that is an example of poor design IMHO.  To rely on
an external device for such protection is to rely on a device that also
is subject to failure - in other words, poor design IMHO.

73,
Don W3FPR

On 7/29/2014 9:54 PM, Josh Fiden wrote:
> Just to clarify... use of ALC with the PW-1 is not to adjust drive
> power. That's a bad practice. You MUST use the ALC line because the
> amp uses this as a primary means of protection. Without ALC, a fault
> condition can damage the amp.
>

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[Charlie T, K3ICH]

> Just to clarify... use of ALC with the PW-1 is not to adjust drive power.
> That's a bad practice. You MUST use the ALC line because the amp uses this
> as a primary means of protection. Without ALC, a fault condition can
> damage the amp.
>
> 73,
> Josh W6XU

Well, yes it is when connected to an Icom transceiver it is used precisely
to control drive power.

I have the PW-1 connected as recommended in it's manual to an IC-7600.  My
output control is set for about a hundred watts barefoot and 1 kW when the
amp in enabled.   The output power when driving the PW-1 is far less than
100 watts and the only thing controlling the drive is the ALC line.

Besides, I thought that's exactly what I said.....

The proverbial fly in the ointment is that the I don't believe the KX3 HAS
and ALC input.

Chas


----- Original Message -----
From: "Josh Fiden" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, July 29, 2014 9:54 PM
Subject: Re: [Elecraft] KXPA-100 to ICOM PW-1 amplifier

> Just to clarify... use of ALC with the PW-1 is not to adjust drive power.
> That's a bad practice. You MUST use the ALC line because the amp uses this
> as a primary means of protection. Without ALC, a fault condition can
> damage the amp.
>
> 73,
> Josh W6XU
>
> On 7/29/2014 12:41 PM, Charlie T, K3ICH wrote:
>> You better make sure you have a reliable ALC connection in there
>> somewhere because you'll smoke the PW-1 if you hit it with a hundred
>> watts.  They normally take about 35 -45 watts drive for full output.
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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[Josh Fiden]

Sorry, my error. You CAN use ALC to control drive power, but it should
not be used for that purpose. If you set the transceiver to 100W and let
ALC reduce it during normal operation, you generate trash in your
transmitted signal.

Prior to replacing my Icom transceiver with the K3, a neighbor
complained that I had bad key clicks. Turning down drive power on the
transceiver, rather than relying on ALC, substantially improved my
signal. This was using a PW-1.

PW-1 uses ALC for protection. Unless I misunderstand, running the PW-1
without ALC, even directly from a KX3, may not be a long term reliable
solution.

73,
Josh W6XU

On 7/29/2014 8:05 PM, Charlie T, K3ICH wrote:
>
> Well, yes it is when connected to an Icom transceiver it is used
> precisely to control drive power.

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