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@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Tom
Osborne
Sent: Thursday, January 01, 2015 20:09
To: towertalk@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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