adjusting the K3 to not over-drive an amplifier

[Tom Whiteside]

I've had my K3 for 8 years now and just love it...  My only complaint is
that in SSB I have trouble throttling the power back enough to not
occasionally trip an Alpha 87A.  The K3 just ignores the reins and charges
ahead...   I notice this on a 40M sked where my antenna is close to 2:1 SWR
- It doesn't seem to misbehave into a dummy load so I'm thinking it is
related to that...  (The antenna is a beam stack on a tower over 400 feet
away and not pointing at me so it's not an RFI issue...)  I've rerun the
power calibration routines with no difference noted.  Headset is a
Radiosport and mic gain is down to 5 compression level of 11.

I know this group will be able to tell me just how to correct this.

Tom N5TW

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[Wes (N7WS)]

Since your amplifier is rated only to SWR <= 1.5 maybe that is the issue. What's
the fault indicator telling you?

Wes  N7WS



  On 1/2/2015 9:10 AM, Tom Whiteside wrote:

> I've had my K3 for 8 years now and just love it...  My only complaint is
> that in SSB I have trouble throttling the power back enough to not
> occasionally trip an Alpha 87A.  The K3 just ignores the reins and charges
> ahead...   I notice this on a 40M sked where my antenna is close to 2:1 SWR
> - It doesn't seem to misbehave into a dummy load so I'm thinking it is
> related to that...  (The antenna is a beam stack on a tower over 400 feet
> away and not pointing at me so it's not an RFI issue...)  I've rerun the
> power calibration routines with no difference noted.  Headset is a
> Radiosport and mic gain is down to 5 compression level of 11.
>
> I know this group will be able to tell me just how to correct this.
>
> Tom N5TW
>

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[Mike K2MK]

Hi Tom,

Since it behaves into a dummy load it's probably the SWR but you could also take a closer look at the TX gain calibration. Even after running the calibration routine I have had to touch up the numbers on a couple of bands.

Take a look at the K3 manual page 62 for TXGN{pwr}. The last paragraph gives advice on changing the setting manually. Put the K3 on 40 meters, turn off TX ALC and reduce TXGN slightly. Then turn on TX ALC and give it a try.

73,
Mike K2MK