Grid input network for K1JJ 813 rig

[WD8BIL]

If you do choose powdered iron you'd wanna stay with the XX-2 mix. Ex: 2" core would be 200-2 as Amidon calls'em. They're painted a dark red. Above 40 meters choose a -6 (yellow) mix.

[KL7OF]

Steve..Did you look at the grid tuner from the cal handbook referenced in an earlier post by me..  I took some of tom's suggestions and made a few little  mods and got it working very well with waaay more grid current than needed for MAX output.  The 813s properly neutered drive very easily...It doesn't take much current or voltage  on the grid so the bread slicers can be very close spaced and the coils easily wound.  As I write this, I wish I could remember more specifics but alas it was a while ago when I built my tesla...I had a lot of forum help.  Good luk ....

[w9jsw]

This is my go-to for this application.

https://www.rfparts.com/capacitors/capacitor-airvariable-panel-mount/20apl300de.html

John

[KK7UV]

Thanks Steve - I checked out the ideas in some 'Calif.' handbooks (presuming you mean the E&E/Orr Radio Handbooks).  They look the same or similar enough to what I am going for.  I have some B&W 3015 coil stock and a good selection of variables in the 150 - 360pF range and am building it similar to what W3RSW did.  It will be easy to swap out other variables if I need to.  Some fun experimenting coming up!

John - Thanks for the link to RF Parts.  I have a Hammarlund variable that looks very close to that and is my testing pile.

I thought I'd try a 40-turn piece of the coil stock (around 15µH) for 75m and tap it for 40m.  For 160m, I will have the bandswitch add a T-130-2 toroid wound with another 15µH in series for 160m use.  I could also have the bandswitch add a mica padder cap in parallel if the variable isn't enough for 160m tuning.

[w9jsw]

Here is the coil I used for both my 813 and the 4-400. This is the 4-400 one still under construction. The coil is tapped for 160-10M.

[W3SLK]

I have a coil set made by Bud for the Hose-Nose 500 currently in drydock. It is covers 160-10 and is to be used with a 100 pF variable. When I get home I will take a photo. But like some of the older B&W coil stock the partitions on the coils are beginning to deteriorate.
Edit: Here are 3 photos. I have one more.

[W3SLK]

Some of the coils do double duty I am sure since a couple of them are split. 160M/80M, 40M/15M, 20M and 10M coils.