During the past weekend I participated in the phone Sweepstakes and observed high VSWR on my OMNI-VII while driving my Titan 425 using the published settings for 75 meters when operating between 3.8
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Wed, 24 Nov 2010 18:48:22 -0600
High swr seen by the exciter points to the cathode circuit tuning. It may need to be adjusted if there are two input circuits for 80 and 75. Typically the Q of that cathode tuned circuit is very low
At some point, changes were made with the values of the capacitors around the bandswitch in the output stage. There is one less capacitor there than is shown in the manual. With the 3 Titan 425s I ow
Jim, I believe you have the answer as my TITAN 425, S/N 425-00516 (labeled as an export model) was sent back to TenTec for warranty work and upgrades shortly after I purchased it new from AD0S. The T
I use the recommended (by TenTec) method of tuning the TITAN 425.... alternate TUNE and LOAD for maximum power out for a given drive, increase/decrease drive and adjust TUNE and LOAD for max power ou
That is exactly right. And doing that will also minimize grid current, which is the main factor in tube life. 73, Jim K9YC _______________________________________________ TenTec mailing list TenTec@c
Hi Gary, You never said what your load Z was but it together with your feedline length could require more inductance in the amp's pi network. Once you adjust the "tune" and "load" caps for maximum ou
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 25 Nov 2010 10:50:31 -0600
According to the downloaded manual, the ONLY thing that changes between 75 and 80 meters is the value of the fixed capacitor at the loading point in the output Pi-L network. The coil taps and the inp
There are no individual tuned input matching circuits on a Titan 425. Basically the exciter drives the cathodes of of the two 3CX800A7s. The recommended feedline between the exciter and the amplifier
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 25 Nov 2010 13:06:46 -0600
The manual I have shows individual input circuits called low pass filters on the input low pass filter board. 81223. There is no more output filter after the PI-L. There is one per band from 160 thro
After careful review you are correct ("a rose by any other name is still a rose"..W.S.). 73 es DX, Gary - AB9M The manual I have shows individual input circuits called low pass filters on the input l
I use the Centurion amp, and noticed that the tune control has essentially no effect on grid current, and the load control has no effect on almost anything, except at very wide deviation from the rec
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 26 Nov 2010 09:51:20 -0600
In the Titan, and I've not looked at the Centurion, schematic on 40, 80 and 160 the load capacitor has a large shunt fixed capacitor so the variable is a small part of that capacitance so it has only
I'm probably missing something but it appears to me the only difference between the 75 and the 80 meter switched components is at bandswitch S1B where C19 (150 mF ) is switched out in the 75m positio
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 26 Nov 2010 12:18:06 -0600
That's the way I see it. Taking out C 18, 300 pf fixed requires adding that back with the variable loading capacitor. The cap labels are to the left of the part. And with the variable having only 500
right C 18 not C 19..... using the 75 m switch position the LOAD control is always at 10 or full mesh (not enough total capacitance)... using the 80 m switch position the Load control is at 2.5 or so