Current requirements for KPA100?

[Bill Coleman-2]

During a recent contest, I received a report of poor signal quality on
my CW signal on 80m.

I've run some tests and find that on 80m and 160m, there's a distinct
hum on the signal when running over about 80 watts. I've also noticed
that the current used seems to jump in discrete steps as I increase the
power level. It could be that this hum is present on the power supply
at higher current levels. On 160m, the rig pegs the scale on my power
supply ammeter when running full power.

Do the current requirements of the KPA100 increase on these bands? And
what would cause the discrete steps in current consumption at the
higher power levels? We're talking a jump in current about every 10
watts or so.

Prior to the contest, I performed the KPA100 modifications for high SWR
operation and installed the new firmware. I've noticed that the heat
sink is running noticeably hotter than before. This while transmitting
into a 50 ohm dummy load.

Any suggestions would be appreciated. The rig appears to operate just
fine, I'm just a little concerned about the signal quality and the
extra heat.


Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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[Ron D'Eau Claire-2]

Your idea of hum coming from higher current sounds plausible here,  Bill.

You didn't say what your K2/100 is actually drawing but, yes, mine draw more
current on 160 and 80 than on most other bands.

I plugged in a dummy load and here's what mine requires at 100 watts on each
band:

160m = 17.5 amps

 80m = 17 amps

 40m = 14 amps

 30m = 15 amps

 20m = 14.5 amps

 17m = 17 amps

 15m = 17.5 amps

 10m = 15 amps

That's total current reported by my Astron power supply.

Ron AC7AC

-----Original Message-----
During a recent contest, I received a report of poor signal quality on
my CW signal on 80m.

I've run some tests and find that on 80m and 160m, there's a distinct
hum on the signal when running over about 80 watts. I've also noticed
that the current used seems to jump in discrete steps as I increase the
power level. It could be that this hum is present on the power supply
at higher current levels. On 160m, the rig pegs the scale on my power
supply ammeter when running full power.

Do the current requirements of the KPA100 increase on these bands? And
what would cause the discrete steps in current consumption at the
higher power levels? We're talking a jump in current about every 10
watts or so.

Prior to the contest, I performed the KPA100 modifications for high SWR
operation and installed the new firmware. I've noticed that the heat
sink is running noticeably hotter than before. This while transmitting
into a 50 ohm dummy load.

Any suggestions would be appreciated. The rig appears to operate just
fine, I'm just a little concerned about the signal quality and the
extra heat.


Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"


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[Bill Coleman-2]

Gary Surrency provided part of the answer.

He suggested that I reset the bias adjustment and re-calibrate the SWR
bridge. After doing this, I'm no longer getting hum on 80m, and on
160m, the hum is reduced.

So, if any of you do the KPA100 upgrade, be sure to re-do these
calibrations.

On Aug 16, 2004, at 1:19 AM, Ron D'Eau Claire wrote:

> Your idea of hum coming from higher current sounds plausible here,  
> Bill.
>
> You didn't say what your K2/100 is actually drawing but, yes, mine
> draw more
> current on 160 and 80 than on most other bands.
>
> I plugged in a dummy load and here's what mine requires at 100 watts
> on each
> band:
>
> 160m = 17.5 amps
>
>  80m = 17 amps
>
>  40m = 14 amps
>
>  30m = 15 amps
>
>  20m = 14.5 amps
>
>  17m = 17 amps
>
>  15m = 17.5 amps
>
>  10m = 15 amps
>
> That's total current reported by my Astron power supply.
>
> Ron AC7AC
>
> -----Original Message-----
> During a recent contest, I received a report of poor signal quality on
> my CW signal on 80m.
>
> I've run some tests and find that on 80m and 160m, there's a distinct
> hum on the signal when running over about 80 watts. I've also noticed
> that the current used seems to jump in discrete steps as I increase the
> power level. It could be that this hum is present on the power supply
> at higher current levels. On 160m, the rig pegs the scale on my power
> supply ammeter when running full power.
>
> Do the current requirements of the KPA100 increase on these bands? And
> what would cause the discrete steps in current consumption at the
> higher power levels? We're talking a jump in current about every 10
> watts or so.
>
> Prior to the contest, I performed the KPA100 modifications for high SWR
> operation and installed the new firmware. I've noticed that the heat
> sink is running noticeably hotter than before. This while transmitting
> into a 50 ohm dummy load.
>
> Any suggestions would be appreciated. The rig appears to operate just
> fine, I'm just a little concerned about the signal quality and the
> extra heat.
>
>
> Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
> Quote: "Not within a thousand years will man ever fly!"
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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