[TenTec] Ig drift on amps

Ken Brown ken.d.brown at hawaiiantel.net
Thu Feb 12 01:43:50 EST 2009

Hi Gary,

> Here's a photo of the blackened wires. 
The enameled copper wire on the big inductor, not the toroid but the 
other one, appears darker than normal to me. The enameled wire in my 
Titan 425 is all pretty near the color of the wire on the toroid in your 
picture. None is that darker shade I see in your picture.
>  In this amp it is a 
> 15KV Series HEC HT57 doorknob and all the other doorknobs are 5KV 
> 828s doorknobs. 
> Anyone know if this cap is stock? 
Mine also had one which was a 15 kV rated one. I think they may have 
done this because that is the only way they could find the capacitance 
value they wanted, at a price they wanted to pay, and not so much 
because they needed the voltage rating. As you have discovered, you 
can't always get what you want (in doorknob capacitors) but if you try 
sometimes, you'll find you get what you need (but you may have to settle 
for higher voltage rating, bigger sized ones).

I have been following this thread, and wanted to give you the list of 
web sites I put together for doorknob capacitors. Unfortunately, it is 
on another computer. One of the names  I did not notice anyone else 
mention is Max Gain Systems. I think their url is something like 
mgs4u.com. Since you already ordered capacitors I guess the information 
is a bit late. Sorry 'bout that.

I put all new 7.5 kV rated doorknobs in my Titan 425 for the tank 
padding capacitors, and some axial lead disk ceramics, much beefier than 
the originals, for the  RF coupling/DC blocking from the anode to the 
tank. When I was all done I still had some Ig drift, but only on the 
dummy load on not on an antenna. I eventually used an ohmmeter to see 
that my termination was increasing resistance as it heated up. the 
increasing resistance must be in the contact to the resistor, because 
the resistor is rated at 250 Watts continuous in still air, and should 
handle 1500 watts in oil with no problem. My termination is is big black 
thing with fins, an N connector and no label. Based on size comparison 
with known terminations and construction it is probably only rated at 
500 watts, and good to 500 MHz or a GHz. I digress.


More information about the TenTec mailing list