Even at low power, large currents can flow in certain components. This sounds
like something is heating up and changing value. A giveaway would be if the
match drifts faster at high power than at low power. Assuming that's the case,
can you get inside and, while running low power, feel around for anything
getting warm?
Kim N5OP
"People that make music together cannot be enemies, at least as long as the
music lasts." -- Paul Hindemith
> On Jan 1, 2015, at 14:09, Tom Osborne <w7why@frontier.com> wrote:
>
> Hi
>
> I picked up an MFJ-989C tuner that has a problem (don't want to hear about
> 'mitey fine junk).
>
> The problem is that the SWR goes down and then slowly creeps back up.
>
> I got a new roller inductor and installed it and the SWR still doesn't stay
> low, even at low power.
>
> I took the roller inductor out and put in a switch/coil combo to eliminate
> the coil problem. SWR still climbs up.
>
> Bypassed the SWR circuitry and ran the input from the antenna directly to the
> capacitor. Still won't stay low.
>
> I thought it might be the SWR circuitry but I put another tuner in front of
> this one and when I tune the SWR down with the other tuner, it stays down, so
> don't think it should be the SWR circuit.
>
> This really has me puzzled. Can't see anything left to check. Any ideas?
> Thanks and 73
> Tom W7WHY
>
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