[Amps] B&W 852 tank inductor question

[David J Windisch]

Hi, thank you, and HNY, all:

Ho-ly cock robin!  What a pleasant surprise of a response on such short notice.  Thank you for all the gorgeous pictures! 

In no special order:

1. From pics, it looks like I can add 2 same-diameter turns to the stock inductor at the 80M end, without major mods, which probably will take care of the 80M syndrome.

2. The use of vacuum relays for switching any external L-C components added has been advanced.

3. It has been suggested to insert a toroidal inductor for 160M like the (Alpha-to-Zulu) manufacturers do.

4. It has also been suggested to lengthen the overall assembly enough to fit in about 12 same-diameter turns of 1/8" tubing or #10 wire to accomodate 160M.  I kinda like that idea, but dunno if the resulting shape-factor will be optimum, or, at least, close enough for government work.  Does any one remember that old length/diameter rule of thumb? Was it 4/3 or am I thinking video aspect ratio?

5. Again from pics, extra switch sections can been added at both ends of the shaft for inserting tuning and loading padder capacitors.

I'm likely to combine the ideas in 1., 3., 4., and 5., ie, putting a toroid at the 80M end of the inductor with 2 added turns, inside a slightly-lengthened frame, with donor sections from a switch of unknown parentage for the tuning-cap and loading-cap padders.

Btw, the Zp I'm using in calculations is 2K (3-1000Z shack heater), and the pi-net formulae come from one of Geo (of happy memory) Grammer's ARRL pubs, iirc, _A Course in Radio Fundamentals_.

Thank you again.  It's most welcome to hear from a good group of amp builders.

Brgds,
Dave, W8FGX