2 x 4x1 amp for 29.1 Mhz

[KL7OF]

Tnx Tom...   That is good infomation for me.  I'll let you guys know what I find. FUN Stuff.

[KD6VXI]

You're going to need 25 volts or more of bias at 5kv, and this is dependent on the condition of the tubes.

You want next to nothing for idle current key down no drive.   On my Sb220, that meant 15 mils key down.

My sb220 had zero issues making legal limit pep on am that way.

--Shane
WP2ASS / ex KD6VXI

[Opcom]

The amp is working with 5KV plate voltage.  I'm very pleased with the performance.  10 Meters has been open and I have been using the amp on AM and SSB with good reports.  I have found several voltage settings that give me slightly over 70% efficiency.  55-60% at most plate voltages.  I have built and painted the rack panels and enclosed the amp. The power supply is in a separate 20 inch Bud rack on casters.
    Driving with a FT102 25 watts AM, the amp will forward modulate a 400 W carrier.  This amp loves voltage and loves drive.  The testing continues...

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Excellent use for CRT bezels! That plastic may not last wothout an air blast. On the othe rhand, if you have a skilled glass shop around they can make you a square piece with holes in it.

[kb3ouk]

Class BC linear service is a nice way to run tubes for an AM only amp. When i used to run a FT-901 on AM i would even use it that way, there was enough range in the bias adjustments that you could pull the tubes below cutoff, and enough drive to be able to still drive it. Less heat out the back, slightly more power out, and I noticed you get slightly extended positive peaks vs running in AB.