K3/100 Voltage Drop when transmitting

I suspect the problem is the power supply and Don has some good
suggestions. I am not sure what the actual K3 power requirements are.
FWIW, Astron's are rated for ICS, if you really want 25 amps continuous
you need a 35 amp linear power supply.

John KK9A



Don Wilhelm donwilh at embarqmail.com
M
Jimmy,

Astron power supplies have a nasty habit of having loose wiring
terminals.  They use only pressure to hold the ring terminals on the
inside to the terminal bolts.
If you can detect even a slight rotation of the bolt when tightening
terminals on the outside, remove the covers and tighten those bolts from
the inside.

The other problem is improperly assembled APP connectors.  If you look
straight into the end of the connector, if you can see the tip of 2
blades in either side, give the contact blade an extra push from the
wire side until the contact blade locks over the locking tab.
That is also a cause of APP connectors which tend to pull out with very
little tension.

73,
Don W3FPR

On 2/25/2019 2:12 PM, James Walker wrote:
> I have a K3 that behaves similarly to what Mike described. I switched
from an Astron 25 amp (15 years or more old) power supply to a switching
power supply. Problem solved. One would think the problem was my Astron
power supply, but I don’t see any such power drop when I use my Astron
with other 100 watt rigs. Very strange.
>
> Jimmy Walker, WA4ILO
> Macon, GA

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[Buck]

There are two adjustments in my Astron 35A supply.  One on the board,
adjusts the voltage.  Another on the meter, calibrates the meter.  I
found my output on the terminals was almost a volt low even though the
meter read full.

I adjusted the pot on the board and then calibrated the meter using two
different VOMs.  Now, all is well.  Trust but verify...

Buck, k4ia
Honor Roll
8BDXCC
EasyWayHamBooks.com

On 2/25/2019 2:44 PM, [hidden email] wrote:

> I suspect the problem is the power supply and Don has some good
> suggestions. I am not sure what the actual K3 power requirements are.
> FWIW, Astron's are rated for ICS, if you really want 25 amps continuous
> you need a 35 amp linear power supply.
>
> John KK9A
>
>
>
> Don Wilhelm donwilh at embarqmail.com
> M
> Jimmy,
>
> Astron power supplies have a nasty habit of having loose wiring
> terminals.  They use only pressure to hold the ring terminals on the
> inside to the terminal bolts.
> If you can detect even a slight rotation of the bolt when tightening
> terminals on the outside, remove the covers and tighten those bolts from
> the inside.
>
> The other problem is improperly assembled APP connectors.  If you look
> straight into the end of the connector, if you can see the tip of 2
> blades in either side, give the contact blade an extra push from the
> wire side until the contact blade locks over the locking tab.
> That is also a cause of APP connectors which tend to pull out with very
> little tension.
>
> 73,
> Don W3FPR
>
> On 2/25/2019 2:12 PM, James Walker wrote:
>> I have a K3 that behaves similarly to what Mike described. I switched
> from an Astron 25 amp (15 years or more old) power supply to a switching
> power supply. Problem solved. One would think the problem was my Astron
> power supply, but I don’t see any such power drop when I use my Astron
> with other 100 watt rigs. Very strange.
>>
>> Jimmy Walker, WA4ILO
>> Macon, GA
>
> ______________________________________________________________
> 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]

John and all,

A 25 amp power supply should adequately power the K3 at 100 watts - but
check the K3 specifications if contemplating 100 watts for DATA modes.
The K3 is rated for ICAS and not for continuous duty.

Also keep in mind that the K3 is a bit different than other amateur
transceivers in the way it controls power.  The K3 attempts to maintain
the power in watts rather than just the drive level when you set the
power knob at 100 watts.
That means if the voltage drops during transmit, the K3 will increase
the drive and maintain 100 watts.  It takes more current to produce 100
watts at 11 volts than it does at 13.8 volts.

73,
Don W3FPR

On 2/25/2019 2:44 PM, [hidden email] wrote:
> I suspect the problem is the power supply and Don has some good
> suggestions. I am not sure what the actual K3 power requirements are.
> FWIW, Astron's are rated for ICS, if you really want 25 amps continuous
> you need a 35 amp linear power supply.
______________________________________________________________
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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Please help support this email list: http://www.qsl.net/donate.html