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External AMP

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rcbenedict1545

External AMP

I am using my ancient Heathkit SB 230 (original tube) with my K3s. Is there a way to get 12 volts out of acc connector to power relay? Using K3 external plug for P3 power.
Ray
W8LYJ

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Nr4c

Re: External AMP

How many Amps does it draw? The external port can supply 1 AMP. The P3 between .5 and .75 A. (Depending on SVGA & TX-MON installed). If you don’t need more than .250 or so you can use a simple RCA>RCA/RCA splitter.

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...nr4c. bill

> On Nov 30, 2018, at 10:02 AM, Raymond <[hidden email]> wrote:
>
> I am using my ancient Heathkit SB 230 (original tube) with my K3s. Is there a way to get 12 volts out of acc connector to power relay? Using K3 external plug for P3 power.
> Ray
> W8LYJ
>
> Sent from my iPhone
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Elecraft mailing list

Re: External AMP

In reply to this post by rcbenedict1545

No. There is no power source in the ACC connector from the K3. Your use of the 12V connector is the right solution.

Jack, W6FB

> On Nov 30, 2018, at 7:02 AM, Raymond <[hidden email]> wrote:
>
> I am using my ancient Heathkit SB 230 (original tube) with my K3s. Is there a way to get 12 volts out of acc connector to power relay? Using K3 external plug for P3 power.
> Ray
> W8LYJ
>
> Sent from my iPhone
> ______________________________________________________________
> 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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Don Wilhelm

Re: External AMP

In reply to this post by rcbenedict1545

Ray,

That relay power is normally provided by the amplifier - you do not need
any voltage from the transceiver unless there is some strange and
unusual circuit involved.

Measure the voltage at the "PTT" or "KEYIN" jack of the amplifier. Is
it AC or is it DC? If AC, it will not work with the K3S which needs for
the voltage to be both positive and DC.

If it is DC, what is the polarity? It must be a positive voltage.

Many older tube amplifier designs depended on hard relay contacts for
keying that cold work with AC or DC and did not care about polarity.
In today's solid state world, one must care about such things.

On 11/30/2018 10:02 AM, Raymond wrote:

> I am using my ancient Heathkit SB 230 (original tube) with my K3s. Is there a way to get 12 volts out of acc connector to power relay? Using K3 external plug for P3 power.
> Ray
> W8LYJ
>
> Sent from my iPhone
> ______________________________________________________________
> 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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>

K9MA

Re: External AMP

The unmodified SB-230 used -130 V to switch the relay. Clearly a buffer
relay or interface circuit is required to use that amplifier with the
K3, or any "modern" transceiver.

Scott K9MA

On 12/1/2018 16:54, Don Wilhelm wrote:

> Ray,
>
> That relay power is normally provided by the amplifier - you do not
> need any voltage from the transceiver unless there is some strange and
> unusual circuit involved.
>
> Measure the voltage at the "PTT" or "KEYIN" jack of the amplifier. Is
> it AC or is it DC? If AC, it will not work with the K3S which needs
> for the voltage to be both positive and DC.
>
> If it is DC, what is the polarity? It must be a positive voltage.
>
> Many older tube amplifier designs depended on hard relay contacts for
> keying that cold work with AC or DC and did not care about polarity.
> In today's solid state world, one must care about such things.
>
> On 11/30/2018 10:02 AM, Raymond wrote:
>> I am using my ancient Heathkit SB 230 (original tube) with my K3s. Is
>> there a way to get 12 volts out of acc connector to power relay?
>> Using K3 external plug for P3 power.
>> Ray
>> W8LYJ
>>
>> Sent from my iPhone
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
> Elecraft mailing list
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--
Scott K9MA

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Bob McGraw - K4TAX

Re: External AMP

In reply to this post by Don Wilhelm

The only thing the SB-230 needs to switch to transmit is to ground the
center terminal of the RCA connector on the back. Now with the K3S you
will need to provide an Amp Interface such as the Ameritron ARB-704.
The switching rating of the K3S Amp Key circuit is not rated for the
voltage through the SB-230 relay.

73

Bob, K4TAX

On 12/1/2018 4:54 PM, Don Wilhelm wrote: