[R-390] 6BF5 S line

[Dan Merz]

Hi,  sorry to post this here but at least it's off the unmentionable
subject,  which I think has been put to rest,  I hope.  I am wondering
how the 6BF5 was wired in a 75 or 51 S line receiver,  e.g. cathode
resistor, (by-pass cap?) ,  screen resistor/voltage,  plate voltage.  I
tried to get the schematic from the CCA site but it kept timing out on
me before it downloaded enough to see.  I am trying to improve the audio
of the 6BF5 in a Mackay 3010,  so why not go to Mecca and see how
Collins did it,  though from browsing the archived Collins files,  I
found that this tube runs pretty hot in the Collins applications.  Even
so,  it seems it is better than a 6AQ5 at the low plate voltages in the
Collins (and similarly low in the Mackay,  140 vdc or so B+ for the
receiver in general).  So if anyone can read their Collins schematic to
give me the details of the hookup,  I'd appreciate it.  In the Mackay,
it uses 150 ohm cathode bias resistor,  has 110 on the screen and 130 or
so on the plate.  The cathode resistor is bypassed with a large
electrolytic,  which I don't think Collins did,  judging from some
comments in some of the archived messages,  thanks,  Dan.