Thank you, That was how it seemed I just wanted to double check.
That amp seems a bit happier on 240 than 120.
From: Jack Brindle <jackbrin...@me.com>
To: Harry Yingst <hlyin...@yahoo.com>
Cc: Elecraft Reflector <elecraft@mailman.qth.net>
Sent: Sunday, March 22, 2015 4:20 PM
Subject: Re: [Elecraft] KPA500 Proper Transformer Tap setting
The one that keeps the no-load HV in spec and gives you the best performance.If
that is the Red tap, then use that one.
The two sentences are not in conflict. You should expect a major drop in HV
onkey-down due to losses in the power supply. This includes the components
inthe KPA500 (transformer, etc), the power cord, plug, wall outlet and wiring
allthe way to the main pole transformer. You can’t do much about most of
this,but making sure the power cord can handle the current without overheating
isa great idea. Of course this problem is worse with a 120V supply than
240Vsince the current is proportionately higher.
So, again, if the red tap gives you better output and keeps the HV within the
85Vspec under no-load conditions, use it. Make sure it meets both conditions,
though.
73,
Jack B, W6FBElecraft Engineering
On Mar 22, 2015, at 1:10 PM, Harry Yingst <hlyin...@yahoo.com> wrote:
My line voltage is 239 (which calls for the yellow tap) but on Key down it
sags to 59v
With the Red Tap it only sags to about 66v (80.7 no key)
So The proper tap would be?
From: Jack Brindle <jackbrin...@me.com>
To: Harry Yingst <hlyin...@yahoo.com>
Cc: Elecraft Reflector <elecraft@mailman.qth.net>
Sent: Sunday, March 22, 2015 3:58 PM
Subject: Re: [Elecraft] KPA500 Proper Transformer Tap setting
Both. The HV is directly proportional to the line voltage. This makes sense,
since the HV is derived through a linear transformer.
If your line voltage rises so that it causes the HV to go too high (spec is 85,
the KPA faults at 90V), then you have set the tap incorrectly.
Set the tap according to your line voltage as described on page 9 so that it
gives you nominal HV in the range as described on page 17.
- Jack Brindle, W6FB
Elecraft Engineering
> On Mar 22, 2015, at 11:49 AM, Harry Yingst via Elecraft
> <elecraft@mailman.qth.net> wrote:
>
> In the manual on page 9 it shows to set the tap for the line voltage, but on
> Page 17 under Note it states
> "The KPA500 operates to full specifications when the HV under full load
> isbetween 60V and 85V as shown on the LCD (Tap HV to display the voltageunder
> CW “key down” conditions at full power). The maximum voltage is setusing
> transformer taps as described on pg. 9."
> Which is correct?
>
>
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