[ARC5] BC-AP-0229

[David Stinson]

-----Original Message-----
>From: CharlesWhite <CharlesWhite at hughes.net>
>Sent: Sep 22, 2010 3:13 AM
>To: ARC5 at mailman.qth.net
>Subject: [ARC5] BC-AP-0229
>
>Looking for the pin outs for a BC-AP-229 receiver. Thanks in Advance

45 - 12 VDC Fil.
46 - RF Stage c`athodes
47 - No Connection
53 - Ground
54 - Ground for Manual Volume Control, open for Automatic.
55 - Audio Out
56 - Connect to pin 57 through 1500 Ohm, 10 Watt resistor*
57 - B+

*You can use a much smaller-wattage resistor 
between 56-57 if you lower the B+ into 
the 90-100 volt range.
You'll still get plenty of audio.

For Automatic Volume Control: 
Ground pin 46.  Volume control 50 kOhms between pin 55
(yes; that's audio out.  The volume control on AVC
shunts a variable amount of the audio output to ground).

For Manual Volume Control:
50 kOhm pot in series with 200-Ohm 1/2 watt 
between pin 46 and ground.
Audio still taken from pin 55, but without the shunting pot.

There's a pi-section low-pass filter directly in the
audio-output line.  The coil and caps for it are
mounted on the back chassis skirt.  If you want more 
highs in your audio out, disconnect the ground
to the capacitors and jumper the coil.  I did with mine
and it sounds really sweet.

The plate bypass cap at the audio output is prone
to shorting if you run full B+.  Watch for it-
your audio out will die; not even tube noise out.  
You can snip the wire off one end and a replacement
will fit between the old cap can and the chassis.
Never had any trouble with the other caps.

If you match the speaker properly and run 
around 120-150 volts B+, you'll get
all the audio out you can stand.
I use a cheap 70-Ohm-to-voice-coil 
transformer you can find about anywhere.
Don't remember the tap... someone here does.

Antenna matching cap is multi-turn and
needs to be "right" or the set is deaf.

If you have any trouble, let me know.

Good luck!
73 Dave S. AB5S