On Apr 2, 2006, at 11:52 PM, Steve Thompson wrote:
>
>
> Dan Hearn wrote:
>
>> I don't believe there is room inside the chokes for two 2watt
>> resistors in
>> parallel. I think the 2 parallel 1 watt resistors might run cooler
>> than a
>> single 2 watt job in this spot.
> Yes, they might have larger surface area, but they're still carbon
> comp,
> which is a fundamental flaw. Heat will change their value - not just
> running on 10m, but conducted and radiated heat from the tube. There's
> bags of room for a 3W metal oxide resistor, which will be far more
> trustworthy.
>
> Steve
Indeed, Steve, and to improve the VHF suppressor's performance, replace
the Ag-plated high-Q L with an L made from a more resistive material.
For example, the measured Q of a 922's orig. suppressor is c. 5 at
100MHz, and the Q of a suppressor made from #22 Ni-Cr wire is c. 1.5.
The benefit is a roughly 2/3 reduction in the 3-500Z's gain at 100MHz
-- which is definitely not good news for those who are trying to build
a VHF oscillator.
- end
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
Rich Measures, 805.386.3734, AG6K, www.somis.org
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|