>> If Mr. Rauch wanted to disprove the VHF oscillation theory, he would
>> recommend testing Rs (the VHF suppressor R) to see if its resistance
>> increased substantively. . It seems that someone is using filtered
>> science.
>
>Rich, your test seems to infer that VHF oscillation is the only thing
>that could cause a substantial increase in Rs. Is that the case? If
>so , is there a discussion somewhere that could be read?
>
>cheers, Paul
>ve7cqk
As I recall, this subject was touched upon in "Parasitics Revisited"
[QST, 9/90 - 10/90] and in "Improved Anode Parasitic Suppression......."
[QST 10/88] It was also covered during the VHF parasitic oscillation
debate, which may still be available in Will, KN6DV's archive.
Briefly:
There are two, fairly distinct types of Rs damage. Slow and fast. Slow
heating damage is the usually the result of using to much inductance in
Ls for 10m operation. Change in resistance is typically less than +50%
with a carbon resistor--unless the resistor burns out completely.
Damage to Rs from VHF energy is characterized by little or no sign of
external heating and a large change in resistance. This happens fast. A
'big-bang' is often heard. I have seen 100 ohm 5% carbon-comp. Rs
resistors that measured over 400 ohms--yet appeared to be in good
condition. OTOH, Rs can be burned out completely by VHF energy.
Since Rs can be completely burned out by either VHF or HF energy, it is
technoblatherous to state that only VHF damage can cause a substantial
increase in R. . However, a substantial increase in R with no external
signs of damage is probably VHF-related.
Rich---
R. L. Measures, 805-386-3734, AG6K
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