Been working on a 2 tube reflex radio from a 1923-24 Radio Broadcast publication and thought I would share what I now hear. Just 9 seconds though, click on the picture.

Love it!

Hank

Awesome.

Sounds great! What sort of sensitivity are you getting from it, as far as DX stations?

I can pull in a lot of stations at night but the selectivity is bad.

Looking at building a 2 tube Doerle to replace this - just have not found the coil data for MW.

Great, and how appropriate that you tuned in KDKA, that station being a pioneer and about four years old when your radio plans were published.

The 2 tube Doerle is a sweet perfomer. Good sensitivity and selectivity. I can listen to a strong station across the room using 45V B+.

Calculate your coil to fit your variable capacitor. To tune MW you will need at least 365pF. 400 pF would be better.

The higher the C the higher the Q and selectivity, even 1000pf for the low BCB isnt excessive and Cardwell made them in the 20's with a fairly small .030" spacing so they arent for big transmitters.

Of course a 2 or 3 gang 365-400pf BC style could be wired in parallel.

Carl

Brian:

Do a Google search for Bill "Exray" Meacham's contact information. He built some 2 tube Doerle's in the past and can probably provide you with all of the information, coil and otherwise, that you'll need.

In fact, Bill built quite a few homebrews...that you'll see once you've located his webpage.

BR,

Terry

Bill's website is here:
http://sparkbench.com/
A contact email address is there.

His 2-tube Doerle is shown on this page:
http://www.sparkbench.com/homebrew/homebrew.html

BTW there are at least 2 different 2 tube Doerle circuits out there. One uses a throttle capacitor another uses a pot on the B+ to control the regen.

I prefer the B+ control because pots are cheaper (especially if you are using vintage components), easier to mount, not sensitive to hand capacitance and I have found they are less touchy, and require less adjustment as you change frequency.

I also omit the antenna capacitor or winding and just use a "gimmick" capacitor by wrapping an alligator lead around the antenna lead in. (Antenna length is a factor here.)

Kevin "krystallo" can verify that my 2 tube Doerle works best with an alligator clip simply clipped onto the insulation of my 300' longwire lead-in.

Your mileage may vary.

I have visited Bill's site many times.
Thanks for the link