[Elecraft] 160 Power loss

[Masleid, Michael A.]

Hi Bob,

>Switch to 1850 -
>power level starts close to normal and decays over 20 seconds to zero
>power. This shows on the internal meter (ATU=3DPout) and an external =
power
>meter. At end of decay display will alternate between 0.0 watts out and =
a
>Hi Curr message.=20
>Tuning receive signal loss is evident whenever transmit power is low.
>Receive sensitivity goes to zero.

Some possibilities:

Hook up an antenna to the RX antenna, and use RANT menu to select it
for 160 meters, see what you can hear.  Heat things up at 1850 KHz,
and see if the receive sensitivity still goes to zero.  If receive
sensitivity is still good, the problem is in the low pass filter on
the R160RX board, or else the antenna tuning unit.  If the receive
sensitivity is zero on the RX antenna, the problem is in the band
pass filter on the RF board.=20

Sounds like something is getting hot, and it depends on frequency.
Most likely in the low pass filter or band pass filter.  My guess is
that it will be hot enough for the burnt finger test.  The parts around
L5 are suspect, but not likely, because there's not much power at that
point.  Look for heat at C11, C12, C13, C14, C15, and C16.  With C13
and C14 unique to 160 meters.  Also L5, L3, and L4.  More serious power
is going through the low pass filter on the K160RX.  Look for hot
connections and hot capacitors (and cores?).  These are C1, C2, and C3
on the K160RX board.

Of course, don't touch them while your transmitting.

73, Michael, AB9GV