[TenTec] Titan tuning drift on 160 meters

[Jim Miller]

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 at 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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