>2 wrote:
>
>K7FM had written:
>>>I do have a Collins 30S-1 amplifier. It does
>>>not have parasitic suppressors.
>>
>>** Vern Baumgartner, a friend who worked as an engineer at Collins
>>Radio told me that Ni-Cr alloy was used as a conductor in the
>>4cx1000A's anode circuit.
>>
>Let's be careful with the facts here. Looking at the schematic of the
>30S-1, there is no conventional R/L parasitic suppressor.
** who said there was a R/L suppressor in the 30S-1 ?
>There is an
>"L101" between the anode connector and the HV blocking cap, right where
>you would expect a parasitic suppressor to be. The photograph shows a
>substantial inductor of 3-4 turns of thick wire, about 0.75-1in diameter
>and 2-3in long.
>
>This is the only place where it could make any conceivable sense to put
>a parasitic suppressor; but what L101 is made of, the manual sayeth not.
>
>At a glance, there's something connected to the anode called "Z-101"
>that looks like a parasitic suppressor, but it is in the path to the
>capacitive divider that provides RF negative feedback. In that location,
>Z-101 cannot damp the VHF parasitic resonance of the plate circuit.
>However, this deliberate additional RF feedback path will also make the
>30S-1 behave differently at VHF than amps that don't have this feature.
>
>The 30S-1 is a unique amplifier. It contains many RF, power-supply and
>mechanical features that were highly innovative and individual to that
>amplifier. Some of these features will only work together as a
>"package". Attempts to copy individual aspects have generally not been
>successful, because the copiers weren't as smart as the original Collins
>engineers, and didn't understand how everything interacts.
>
>In short, the 30S-1 is a dangerous precedent for *both* sides of the
>nichrome controversy!
>
** I was unable to confirm Vern Baumgartner's (W6HW) statement about the
30S-1, which is why I omitted it from the January, 1994 QST article.
However, in the 8169 and 8170 amplifiers I built, instead of a
conventional R/L suppressor, I tried the idea of a resistive anode
circuit conductor. It seemingly worked. In the 8170 amplifier, there
were several big-bangs before I switched to a more resistive conductor.
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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