You don't want to be physically modifying by adding coils.
The fix could be to bend the 10 meter section only of the tank coil
slightly.
It should only take 1/4". For instance the difference between a 77DX and
77SX was we needed to stretch the 10 meter section of the coil up to 1/2"
longer in the SX... (and I did just a tad on 15 too) The lower plate
impedance required less inductance (and more cap) it worked fine on all
bands but 10... so try a slight stretch.
BOB DD
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Phil Clements
Sent: Thursday, December 21, 2006 2:41 PM
To: 'Rich Hallman - N7TR'; 'Gary Myers'; amps@contesting.com
Subject: Re: [Amps] Pi-L Tank on TenTec Titan 425
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Rich Hallman - N7TR
> Sent: Thursday, December 21, 2006 12:22 PM
> To: Gary Myers; amps@contesting.com
> Subject: Re: [Amps] Pi-L Tank on TenTec Titan 425
>
> I have seen this as well with the two Titan 425's I have. Seeing a fix
> here would be great! I love the amp....but would love to see the tuning
> more in the "mid-range" of the tune sweep.
>
> Thanks...
> Rich
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Gary Myers
> Sent: Thursday, December 21, 2006 8:07 AM
> To: amps@contesting.com
> Subject: Re: [Amps] Pi-L Tank on TenTec Titan 425
>
> Help!
>
> I have a nice Titan - works great for the most part even with a
> 20 year old tube... however on 10 meters the "peak" on the tune
> capacitor is right at the minimum capacitance point above about
> 28.1 Mhz. Is there anything I can do, simply, to raise this
> just
> enough to know I am tuned properly (i.e. requiring LESS
> capacitance)?
A "fix" has been shown for many years in the ARRL Handbook, and others. You
install a small inductor between the plate block capacitor and the tune
capacitor. The problem is that some "bread-slicer" style tuning capacitors,
along with stray C, result in too much C for 10 meters even when fully
unmeshed. You just add enough coil to make the resonant point attainable
with the tune C at 29 mhz. Too much coil could screw up the settings on
other bands. Check out the Handbook for details.
(((73)))
Phil Clements, K5PC
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