ALC voltage input to the K2?

[omehegan]

I'm working on keying an external amp with my K2. I'm using this
example circuit from the Elecraft site:

http://www.elecraft.com/Apps/Amp_keying_ckt.htm

The amp is a Tokyo Hy-Power HL-45B. In addition to closing the STBY
and GND pins on its accessory jack to key the amp, it also has an ALC
pin that it wants hooked up. The manual says:

"In order to keep the output within the maximum limit and to avoid
signal distortion, ALC connection is most effective. Negative DC
voltage of 0~8V max. will appear according to the amp output level.
When this voltage (ALC voltage) is fed back to the radio, it works to
have the radio’s output power suppressed according to the ALC voltage
applied to the radio."

Is there any convenient place in the K2 where I could feed in this
voltage to get the desired effect?

--
Owen B. Mehegan ([hidden email])
"He is a dangerous mixture of sophistication and recklessness which
makes one anxious about his influence on other boys."

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[Don Wilhelm-4]

  Owen,

The short answer is NO.

The correct longer answer is that you should use the transceiver power
level to control the output of the amplifier and not depend on the
amplifier ALC.  Using the amps ALC to control the power level of the
transceiver is an invitation to distortion and degraded IMD in your
transmit signal - be nice to your ham neighbors and do not use the ALC
for power control.

If the concern is for shutdown of the transceiver in the event of an
amplifier fault condition, then it may be a valid concern, but the K2
was designed before solid state amplifiers became widespread and has no
provision for this type of ALC input.

73,
Don W3FPR

On 12/30/2010 6:39 PM, Owen B. Mehegan wrote:

> I'm working on keying an external amp with my K2. I'm using this
> example circuit from the Elecraft site:
>
> http://www.elecraft.com/Apps/Amp_keying_ckt.htm
>
> The amp is a Tokyo Hy-Power HL-45B. In addition to closing the STBY
> and GND pins on its accessory jack to key the amp, it also has an ALC
> pin that it wants hooked up. The manual says:
>
> "In order to keep the output within the maximum limit and to avoid
> signal distortion, ALC connection is most effective. Negative DC
> voltage of 0~8V max. will appear according to the amp output level.
> When this voltage (ALC voltage) is fed back to the radio, it works to
> have the radio’s output power suppressed according to the ALC voltage
> applied to the radio."
>
> Is there any convenient place in the K2 where I could feed in this
> voltage to get the desired effect?
>
> --
> Owen B. Mehegan ([hidden email])
> "He is a dangerous mixture of sophistication and recklessness which
> makes one anxious about his influence on other boys."
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html