[R-390] BFO Question on Newly Acquired R-390A

[Roger Ruszkowski]

Fellows,

Will one  you of you please remind Chuck and I of the size number for the spline wrench.

Chuck,

I see into your future and you are about to acquire a spline wrench.
All the clamps and knobs on the R390 and R390A when assembled with the
proper bolts and set screws have a Bristol wrench AKA spline wrench "drive bit recess"
You will need one of these bit to loosen the BFO extension shaft clamp so you can adjust the BFO.

Look in side the top behind the BFO and band width switches on the front panel.
You will see the BFO and band width switch shafts are extended out of the IF
deck through the front panel with an extension shaft. The shafts have a clamps.

You loosen the clamp.
Turn off the BFO
Center your signal into the 0.1 band pass as you did. 
Turn on the BFO
Grab the BFO shaft at the IF deck with pliers and rotate the shaft until the BFO zeros.
Set the BFO knob to zero
Tighten the clamp.

The BFO is reset. Job complete.

There should be a lock plate under the front panel bushing nut that limits the BFO
shaft rotation to about + and - 3 on the front panel.

The knob should set out from the panel so it does not rub.
But the dog in the knob catches on the lock plate tab to limit rotation.

The IF deck BFO shaft should have groves and lock rings at the bushing in the IF deck. these lock rings
keep the BFO shaft from pulling out or pushing in.

Some day when you get the IF deck out, you will want to check the BFO bellow coupler expansion stress.

With the BFO at zero and the shaft bushing washers in place, you loosen the set screws in one end of the
bellows and let the bellow freely be what ever length it wants to be.
Then retighten the set screws.
As the BFO preamble slug is screw in or out by the rotation of the BFO shaft, the shaft length changes.
The bellows will compress or expand as the extension shafts (chassis shaft and bushing, front panel shaft and bushing) do not
change length.

Common practice is to pick up a set of spline Bristol wrenches on line as a set of Allen wrenches.
Find the size that fits. Grind the hook end off and square it up on the grinder.
Insert the length of bit into a long handle and make your self a spline wrench tool for your R390.
Splines are also available in nice long handle screw driver like hand tools. You can buy just the one you need.
You will not find Bristol or spline bits at the Home Depot. Lowes or Ace stores.
A god tool shop may have a set.

A very small tork bit may get you into BFO clamp.
these bit go in the hex 1/4 drive bit and may get this job done for you.

This tool arrangement will have to large of a diameter to get you into tighter locations.

Visit the R390.net page and down load the R2K manual and begin reading.
I like the R2K because it comes in sections. If you only have dial up and slow speed
getting the manual in parts is a real plus.

The R2K re wright is so much easier to read and understand.

Roger AI4NI