Progress on the 813 amp; not vaporware anymore

(1/8) > >>

W3RSW:
Construction pix as of today.
Large parts placement complete and temporarily installed on plastic chassis overlay.  Most large holes and cutouts done, just the little stuff to go.  That'll be at least 50% of the work. Plus the wiring.  Still designing the input circuit. Probably will be separate coil/cap. for 160, 75 and 40; not like my single 813 rig, The  "Shoebox" which had one tapped coil and dual 365pf for tuning.  I need to get a decent plate choke; note the homebrew one wound on an oak broomstick handle.  Ho.ho. Well it worked ok on a single 813.

I'm leaving room in front left of deck behind the meter shield for a separate xtal osc. and buffer amp/driver  which may be installed after I play with the amp for awhile lashed to the Drake TR7 for carrier driver/receiver.  Mod drive is provided by a 25 watt PA amp into currently 811's soon to be triode connected 813's.

Iron from left to right is screen audio choke, bias fil./ Ry voltages(OA2 in front) and Raytheon fil. xfor for 813's.  The "Ray" is too big so will be buffered down with a 50 ohm, 50 watt r. in primary.  The bias will be OA2 for neg. 75 into grid resistor for next -75, a la K1JJ.  The 7kv tuning cap is under the quad loading cap (from some ancient TRF radio?)  Boy they sure don't make radios like they used to.

This deck will go into the top of the 32" rack that I picked up at Howard Co. fest a few years ago.  Power supply and modulator mostly done.

Can't wait to get this on 160 particularly in such a lousy 80 meter season. Shoebox is not working now since I "borrowed" a few components.

Rick

John K5PRO:
Nice work, great looking layout there! Gud Luck with her, I think you got a decent project there.

WA1GFZ:
Very nice but a suggestion. Swap plate tune cap with band switch to make distance between the tubes and plate cap short. Stability issue.

W3RSW:
Thanks John, it's been fun so far. 
- And 'GFZ', good point. Your wish is my command.

Meters are now on right side; panel simply flipped around. Nothing like symmetrical layout and Ctr. line drilling to make this sort of thing easier. Also the Screen AF choke is simply placed under chassis, same holes looking up with sufficient clearance for plate tune cap (now on posts, rotor will be grounded of course.)

Steve - WB3HUZ:
Hey, none of this homebrew talk is allowed on here. We need special section for it.

Navigation

[0] Message Index

[#] Next page