KPA-100ModKt

[Tom Althoff]

Last week I ordered parts to upgrade my unbuilt KPA-100 that was manufactured in Jan 2004 to the current revision.

Instead of receiving a FWKPA100 firmware, KPA100Modkt and KPA-100 Shield upgrade all I recieved today was the shield upgrade.   Mis-communication somewhere I suppose.

I've been sitting with my KPA-100 built except for the resistor changes, xtal change and firmware upgrade.   I would REALLY like to get this thing tested and on the air for this weekend.

1) The mod instructions says the original crystal still meets spec.  What if I leave it in?
2) The mod says the new firmware and the resistor changes allow for delaying power foldback until a 2:1 SWR is reached.  Without the mod it folds back at 1.5:1.  What if I use the old resistors?

My biggest concern is that keeping the older parts might result in an unstable PA or higher than normal spurs etc.  

Is there anyone on this list still running the old value resistors/xtal in their KPA-100?   Any problems with it?

I am definitely going to install the clips and the new shield plus the speaker shield but am tempted to just slap in the old electronic parts and upgrade at some point in the future.

Comments?

Tom K2TA
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[Bruce McLaughlin]

Tom, I've never installed any of the upgrades for my KPA100.  I just
haven't seen the need for them here.  I use a Mosley Pro 67B which tends
to have a somewhat higher SWR at the lower end of 40 (I set the antenna
for a compromise between CW and phone on 40) so I run the output of the
KPA100 through a little B&W 300 watt matchbox.  That presents a 1:1
match to the output of the KPA100 and it seems quite happy.  Without the
matchbox there definitely is significant fold back observable.

The higher bands do not seem to need that.  If I am chasing after the
more elusive DX and wish to make a bit more noise I run the KPA100
output through my Command Technologies HF 2500 and the input SWR appears
to be very close to 1:1 on all bands.  Since I need only about 30 watts
from the KPA100 to drive the amp to levels approaching the obnoxious,
everything works quite well.

In no way do I suggest the mods aren't useful or desirable - - it's just
that I seem to have another way of operating which does the trick.  At
least if the bands are open to any extent, the K2/100 snags DX with good
signal reports.

Bruce - W8FU



Is there anyone on this list still running the old value resistors/xtal
in their KPA-100?   Any problems with it?

I am definitely going to install the clips and the new shield plus the
speaker shield but am tempted to just slap in the old electronic parts
and upgrade at some point in the future.

Comments?

Tom K2TA



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Elecraft web page: http://www.elecraft.com