Mulla oli yksi ylimääräinen kapistus radiossa kiinni, mitä en yleensä siinä käytä.. Nimittäin mikrofoni. Sen kun nyppäs irti niin ongelman hävis eli RF meni ilmeisesti mikrofonin kautta sisään.
Ja varmaan tuo windomi teki osansa... kunnon dipolilla ei välttämättä olis ollu ongelmia.
Mutta hatun nosto taas elecraftille. Laitoin illalla vielä sinne kysymyksen olisko niillä antaa vinkkiä ja vastaus tuli tosi nopsaan.
Hi Jarno,
It could be due to RF getting into the rig, since the 40m band has the most
power gain and if problems are going to happen, that is usually the band on
which they will occur. It might help to try an antenna tuner too, either a
manual tuner or one of the automatic tuners we make such as the KAT100 150w
auto tuner.
But first be sure all of the shield grounding measures are in place
correctly, including the 2 solder lugs between the KPA100 PA shield and one
screw of the SO-230 antenna connector. The 3 spring clips should also be in
place, and making good contact with the insides of the K2 side panels and
KPA100 rear panel. Be sure to remove all paint in the area where the clips
make contact. See the attached template for where to remove the paint.
Also ground the mic connector. I do this by removing the left side panel and
scraping away enough green solder mask right next to the threaded part of
the connector so that I can solder it directly to the PCB ground plane. If
you remove the PCB coating about 1/4 of the way around the threaded portion
of the mic shell, it’s enough to allow a good soldered connection. A tiny
jewelers screwdriver works well for removing the resist. Use the side of a
soldering iron tip and enough heat to get the shell hot enough to take
solder and then apply solder between the PCB and the bottom edge of the
connector shell. Cool the threaded mic connector with a damp rag or sponge
when done, so you don't burn yourself on the hot connector.
Be sure all chassis screws are tight, and all of the green, paint masking
tape was removed where the threaded 2-D fasteners connect the panels. The
mounting screws on Q1, Q2 of the KPA100 PA transistors will loosen after the
first few minutes of operation, and they will need to be retightened.
Do not leave the internal frequency counter probe installed in TP2, as it
can pick up RF and cause problems. It can also be damaged when the KPA100 is
installed due to close clearance between the K2 and the KPA100.
In some difficult cases, you may find it necessary to adjust the length of
the feedline, antenna, or the station ground to change the impedance and SWR
seen by the rig. Changing the feedline by 1, 2, or 5 feet sometimes will
move a hard to match or high RF current or voltage away from the rig. It’s
usually pretty easy to add in or remove a short section of feedline, so that
is one the first things to try after the things mentioned above. Coils of
the feedline or ferrite beads on the DC and RF cables may also be helpful in
some cases.
In some cases where a good RF ground is not possible, such as on poor soil
or a 2nd or 3rd story building, you may need to use an electrical 1/4
wavelength ground counterpoise wire, or an artificial ground tuner like
those made by MFJ. You can use more than 1 counterpoise to operate over
several bands, with each one cut to the proper electrical 1/4 wavelength, if
it is necessary.
If the antenna is close to the rig, or if there is a lot of RF in the shack,
you may need to change the grounding, use a 1/4 wave counterpoise, tuner, or
relocate the antenna. Sometimes just moving the rig around and how it is
connected will calm things down.
Some linear-mode (not switching mode) Astron power supplies have been know
to cause problems when RF gets into their regulator circuit. Try another
power supply if this is suspected, if possible.
Try removing the mic, headphones, or paddles to see if RF is getting into
the rig from that path. Then transmit with the TUNE button and see if the
power control is more stable.
Be sure the RF cables between the rig and the antenna are in good condition,
with no loose or intermittent connections, poor shield connections, or
corrosion.
I assume you installed the 1K resistor across RFC3 on the KPA100, and
checked that the HV bias is at least 110-150VDC or more. The higher the
better, to ensure good RF t-r switch isolation. This is mentioned on the
most recent KPA100 errata, which I have attached.
If the rig just changes the RF output level too much when the Power knob is
adjusted, do the mods shown at:
http://www.elecraft.com/Apps/Power_Control_Mod.html--
73, Gary AB7MY
=========
gary@elecraft.comElecraft Technical Support
niin ja mulla on tuo sivukansien maadoituspaikkojen hionta jänyt tekemättä... oon kai ohjeessa harpannu yli tai en oo huomannu ollenkaan.... siis paikkoja joihin PA:n maadoituskielet osuvat.
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