[ARC5] BFO performance at lower B+ supply voltages.

[Leslie Smith]

  Dennis wrote that the first thing that 'dies' is the BFO.
  True, because the BFO plate supply is fed thru a 'wopping big'
  resistor.  
  The first indication of poor BFO operation is heard when listening to
  SSB - distortion.
  This is not so apparent when listening to CW.


  73 de Les Smith
  vk2bcu at operamail.com


On Wed, Jan 21, 2015, at 09:04, Dennis Monticelli wrote:
> FYI.  My re-cap'd BC-453B pulls 10mA off 60V.  Not much at all.  Of
> course
> you pay some price in terms of overall gain and audio output, but the
> sensitivity is still good enough that antenna noise dominates.  As I drop
> B+ further (heading for 24V) I find that the first function that dies is
> the BFO.  Some radios are still running OK at 24V and some lose the BFO.
> Maybe a fresher tube would make the difference.  I know some folks run
> them
> that low successfully.
> 
> Dennis AE6C
> 
> On Tue, Jan 20, 2015 at 1:39 PM, Bill Cromwell <wrcromwell at gmail.com>
> wrote:
> 
> > Thanks Dennis,
> >
> > I'm takings notes here and looking at what I have. My Kenwood doesn't
> > "seem" to bothered as much so I will look at the power supply schematics
> > but I suspect I am *hearing* less of the crud because of the system
> > passband and much more is seen by the front end - bad! I was surprised by
> > the small amount of current drawn by six tubes from the B+ at 45 and 90
> > volts. I suppose I have become used to larger numbers for the plate current
> > in transmitters. I have several hours on the batteries on the BC-453 now
> > and the batteries are still chugging away.
> >
> > I thought I had a used power connector with the built-in filters left from
> > a swap-fest purchase that included two or three of those units. They are
> > reasonably priced from places like Mouser, etc. I might purchase the
> > individual parts and put them together to handle higher current for
> > transmitter power supplies. A filter built heavier will surely not be
> > harmed by *ANY* receiver.
> >
> > 73,
> >
> > Bill  KU8H
> >
> >
> >
> > On 01/20/2015 12:31 PM, Dennis Monticelli wrote:
> >
> >> On my BC-453 I either run batteries as you do, Bill, or I use HP bench
> >> supplies, which have excellent output noise specs.  The local noise
> >> environment is bad enough as it enters from the antenna without having to
> >> worry about direct feed of line noise into the receiver circuitry.
> >>
> >> Dennis AE6C
> >>
> >>
> >
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