Ken;
Years ago the factory had to change doorknob vendors. I wound up with a
Titan that would drop off as I tuned to 1500 watts, and stabilize around
900-1000 watts. Larry Worth, then Service Manager obtained a different
vendor doorknob and shipped to me. I ran it all weekend long on 160 and
reported my findings to Larry Monday morning. This cured the power drift
problem.
So this may be your only problem.
Good luck-I would think T-T could still supply the doorknob (only
switched in for 160M use) to you.
73,
Jim Miller, K4SQR
http://www.comteksystems.com
4-Square Experts, Stack Yagi
& Remote Antenna Switching Systems
On Fri, 10 Oct 2003 14:44:35 -1000 Ken Brown <ken.d.brown@verizon.net>
writes:
> Hi All,
>
> My Titan 425 has a drift problem with tuning on 160 meters. I have
> posted this question before and got some conflicting answers. All
> seem
> to agree that the problem is caused by capacitors in the tank
> circuit
> that change their capacitance as they heat up, and that the problem
> can
> be cured by replacing the large disk ceramic capacitors with bigger,
>
> better doorknob capacitors. Some have said the problem is in the
> plate
> DC blocking capacitors (the ones that couple the RF from the anodes
> to
> the Pi-L tank, while blocking the DC plate supply) C6 & C7. Others
> have
> said that it is either C15 the capacitor that is paralled with the
> plate
> tuning variable capacitors C14 and C28 when on 160 meters (my
> schematic
> leaves out an important line, and shows C14 and C15 connect to
> nothing
> except ground and the band switch), or the problem is caused by one
> or
> more of the capacitors C16, 17, 18, & 19 which are paralleled with
> the
> variable loading capacitor C21. While it is possible that all of
> these
> capacitors may contribute to the problem, I suspect that there are
> one
> or two that have a larger role in this problem than the rest. I
> wonder
> if anyone can tell me which ones? When I posted a question about
> this
> problem many months ago I got referrals to suppliers of the
> neccessary
> capacitors, which I promptly ignored, because I was sure that I
> would
> find my stock of doorknob capacitors and not need to buy any. Having
> not
> found my doorknob capacitor stock, it seems that I will have to buy
> some
> after all. So I need a repeat of that information too.
>
> Thanks in advance for any help,
>
> Ken N6KB
>
>
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>
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