K3 and ALS1306 Amplifier ALC

[Elecraft mailing list]

Hi, I need some help. I have a K3, the DB9 interface cable and an ALS (MFJ)1306 amplifier. I need to know if the amplifier handles power fold back for SWR by itself or needs to connect to the K3. Question 2 is whether the cable allows this.  I know there is a setting in the K3 for external ALC control.
     What is the proper way to set it up and provide ALC and SWR foldback?
       Many thanks in advance,   Doug K6JEY


 
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[Bob McGraw - K4TAX]

Doug:

The remote and radio band data connectors are specialized connections.
They are for use with Ameritron supplied cables only.  DB-DB15HE

I did see that the HV power supplies do have current limiting which
would imply there is some protection from excessive current based on
load impedance.   And I DID NOT see any specific values related to SWR
power fold back conditions.   Usually SWR values of 1.5:1  or less are
generally satisfactory.   As stated in the manual, PA failures are
generally attributed to excessive SWR values.

Regarding ALC, there is provision for ALC to be supplied from the
amplifier to the transceiver.  I would CAUTION that the set-up of ALC in
this configuration must be done absolutely correctly. Otherwise,  ALC
should not be active at power values less than 1200 watts into a 50 ohm
resistive dummy load.   Antenna loads and impedance's will vary and may
or can cause ALC action at less than 1200 watts rated power.   Most will
recommend that ALC not be used between the amplifier and the transceiver.

The transceiver does allow a power per band setting and I strongly
suggest using this method for power control.  Again, setting the correct
drive to produce 1200 watts into a 50 ohm resistive dummy load is the
absolute correct and maximum drive for the specific amplifier and
band.   Drive power  from band to band will be somewhat different
values.    Adjustment of the MIC gain for correct ALC indication on the
transceiver is imperative.   If you desire more punch, use the Speech
Processor or Compression and do not advance the MIC gain for more ALC
action.

73

Bob, K4TAX


On 1/24/2020 3:08 PM, Doug Millar via Elecraft wrote:

> Hi, I need some help. I have a K3, the DB9 interface cable and an ALS (MFJ)1306 amplifier. I need to know if the amplifier handles power fold back for SWR by itself or needs to connect to the K3. Question 2 is whether the cable allows this.  I know there is a setting in the K3 for external ALC control.
>       What is the proper way to set it up and provide ALC and SWR foldback?
>         Many thanks in advance,   Doug K6JEY
>
>
>  
> ______________________________________________________________
> Elecraft mailing list
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>
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