Tube Anode Suppressor 1 watt Allen Bradley

[n8fvj]

Can a tube anode suppressor be wound on an Allen Bradley 1 watt carbon resistor with 5 turns? Normally 2 watt resistors are used with 3 turns. 5 turns makes up lost inductance on larger 2 watt resistor 3 turn inductor due to smaller diameter AB 1 watt using 5 turns.

[Pete, WA2CWA]

There's no rule that says you have to wrap the coil directly on the resistor. Also, if you plan to wrap the coil around the resistor body, the wire gauge determines how many turns you can fit on the resistor. There are many suppressor designs where the resistor is outside the parallel coil.

[n8fvj]

There's no rule that says you have to wrap the coil directly on the resistor. Also, if you plan to wrap the coil around the resistor body, the wire gauge determines how many turns you can fit on the resistor. There are many suppressor designs where the resistor is outside the parallel coil.

So, you agree 1 watt is ok?

[ka1bwo]

Jim, I have had failures even with 2 watt resistors, cracking with a conditional stability event.
attachments: suppressor type used and measured impedance

[KD6VXI]

There is no 'formula' for turns vs wattage, etc in regards to Psupp's.

They are tuned for a resonance you want to suppress.  Different tubes mounted different ways in different enclosures will all have a resonance in a different place.

Ergo, you have to have the right suppressor for the amp in question.

I prefer a hairpin inductor.  Others smarter than I have stated that it's better to have the coil outside the inductor due to the magnetic field set up inside the coil.  Makes sense, I moved mine to outside the resistors at that time.  Later I moved to a hairpin style just because they where easier to make. Way easier to make a half turn an inch or so wide vs 2 to 5 turns around a small resistor! And way less Cstray to cause issues with the suppressor.

It bears mentioning that the suppressor needs to be in circuit when it's tested.  Making one up using a free air test jig means little when it's installed in a shielded metal enclosure.

Saw your ad selling parasitic suppressors.  When did they come with a wattage rating?  I've never heard such nonsense.  A parasitic suppressor will usually pass more power at the lower frequencies than, say, 10 meters.   But made correctly they will be nearly invisible to the intended pass frequency and be enough to prevent an oscillation from taking off at Fparasitic.

Anyway.....

--Shane
WP2ASS / ex KD6VXI