[ARC5] SCR-183/-283 4-5 MC Coil on 75 MTRs

[David Stinson]

----- Original Message ----- 
From: "AKLDGUY ." <neilb0627 at gmail.com>
Subject: Re: [ARC5] SCR-183/-283 4-5 MC Coil on 75 MTRs


> Referring specifically to the BC-xx-230 model:
> How does one determine the setting for the roller inductor?

I got a pencil, a slide-rule and a stack of paper.
Looked-up the tube characteristics, made exact 
measurements, graphed load lines and 
spent an entire afternoon doing eight pages 
of advanced calculus.

Then I folded the pages into paper airplanes, flew
them out the window and did it by "trial and error."
Took about 5 minutes.

I have both a "stock" 3.2-4.0 MC and a "padded"
4-5 MC coil set for 3890 KC. 
I'll post the tap positions later today or tomorrow when 
I write-up the successful use of 6AQ5 in all stages.

> Has anyone tried using the 1626 triode for VFO and PA?
I did some time ago with a BC-230.  
I jumpered the Modulator filament connections and supplied
12 V to the 1626 filaments.  I made no other circuit changes.
The 1626s neutralized and worked without trouble, delivering
(IIRC)  4 Watts out, which is spec for this little rig.
I don't remember if drift or chirp was an issue with them.
I have not yet tried 1626 in the Modulator stage.
To do so would almost certainly require a minor change 
in the biasing scheme.  I've recently had good success 
doing so with 6AQ5s, which have actually taken the 
"hard service" quite well.  

> If so, what B+ 
Dynamotor B+ of 330 V under load.

>what bias resistor did you use?
With the 1626s as OSC and PA, I made no changes
from the stock 20K grid bias resistor.

73 DE Dave AB5S