[Drake] Drake B Line

[Garey Barrell]

Jim -

The B Line BFO's don't "lock" together.  The C61 trimmer just adjusts
the receiver BFO oscillator frequency to match the transmitter carrier
oscillator.  They will drift apart with time and/or temperature.

The letter at the end of the unit serial number is (or was) a color
code (Green, Blue or Red) that is also a paint stripe on the crystal
in each unit.  This is a code indicating the tempco of the crystals,
so ideally you want units with the same color code, indicating similar
tempco crystals.   This was Drake's response to the problem of drift
in the adjustment in the R-4 and early R-4A series.  The color codes
appeared late in the R-4A sequence and carried throughout the R-4B.

Unfortunately, the crystals have been changed over the years for
repair or to get mismatched units on the same "color" code.  I know of
at least five or six that have been changed... :-)   So the only way
to know for sure what you have is to look at the BFO or Carrier Osc
crystal itself and see what paint stripe, (if any) is on it.  If both
crystals have the same color code, the units will stay together very
well over normal operating temperature ranges.

The C Line oscillators DO "phase lock" when cabled together, so the
transceive drift is no longer a problem.

73, Garey - K4OAH
Atlanta

----- Original Message -----
From: "James C. Owen, III" <k4cgy_list@yahoo.com>
To: <drake@mailman.qth.net>
Sent: Wednesday, February 12, 2003 2:13 PM
Subject: [Drake] Drake B Line


>
>
> > From: "n3drk" <n3drk@bellsouth.net>
> >
> > I have the b line and am being told i am 200 cycles too high in
> > lsb in the
> > transceive position. After adjusting T61 for the proper "canary
> > sound", i
> > still am 200 high according to on air reports. What need i do
> > to correct
> > this?
> >
> > john
> >
> >
>
> John check the BFO Frequency. Also check that the BFO cable
> between the units is connected. Use the instructions in the
> manuals and set the BFO in both units correctly. If the cable is
> not connected then the BFO in each unit is used for that unit, if
> they are different then you won't be where you think you are.
> When the cable is connected they should lock together.
>
> 73 Jim K4CGY
>