[TowerTalk] Tuner SWR won't stay down

[Tom Osborne]

Hi Dave

I did spray the bearings in the caps with some cleaner.  Forgot to 
mention that.

The caps are not grounded in this circuit.


On 1/1/2015 12:18 PM, David Robbins wrote:
> Well, lets see... you bypassed the swr circuit, that's good.  you replaced
> the roller inductor, that's even better, I melted down one of their roller
> inductors at the legal limit years ago.  So all that's left are the
> capacitors... or is there a bypass switch in there also?  its been a while.
> If there is a switch try taking that out of the circuit.  Also check the
> bearing points of the capacitors, if I remember right those are the grounded
> site of the capacitors and could be dirty or have some solvent/lube in them
> that shouldn't be there causing a bad connection that might change as they
> warm up with rf.  Clean them out or put a temporary jumper to the rotor to
> see if that stops the drift.
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Tom
> Osborne
> Sent: Thursday, January 01, 2015 20:09
> To: towertalk at contesting.com
> Subject: [TowerTalk] Tuner SWR won't stay down
>
> 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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