(That's a young James Millen.)
Al Klase - N3FRQ - 2019

I've been a long time fan of  the early short-wave products of The National Company, and the influence of James Millen on the radio industry.  I had accumulated some interesting examples of these products, but was hesitant to restore them to operating condition.

Some recent conversations prompted me to dig some of these  these out, and give them a serious look. 

I've been freaking out for several days now.

10 June 2019
#1  FB-7XA


Case number one was an BF-7AX in pretty good physical condition.  The BF-7 family was a cost-reduced derivative of National's first publically available short-wave superheterodyne the AGS, which in turn was a version of the RHM designed for the  Department of Commerce.

The AGS was far too expensive for the depression era (1932-33) amateur market.



I was really concerned that, like most 1930's radios, complete recapping would be required.  I usually say that what ever you do under the chassis is OK, but this was a special case, as these things are pretty rare, and the workman ship is excellent.

I cautiously applied high voltage from a variable bench supply with the tube heaters cold.  There was little of no leakage.  This is really amazing for 86-year-old capacitors.  These caps, the gray rectangles, are unlabeled, but but some in other sets say "Sprague Midget."  Most are 0.1 uF.   So far, so good!

Years ago, I dissected some known-good paper capacitors from a late 1920's set.  The "condenser paper" was still pure white.  It's my theory that there was a change in the paper industry in the early 1930's.  The paper in may later caps has turned brown, and most of these devices have become electrically leaky.

There is one 10 mfd electrolytic, that is the cathode bypass for the output tube.  I cut it dead, and slipped in a modern electrolytic.  Can you find it
#2  FB-7




This is a "plain" FB-7.  It has the short IF transformers with compression trimmers, and does not have the crystal filter of the "X" models.  This set also came up without a lot of drama.
#3  FB-7XA




I almost wrote this radio off as a basket case.  You'll notice two extra knobs, an extra switch, and an eyetube added to the front panel.  Plus the cabinet is in somewhat worse condition than the other two.  The celluloid dial scale was lying inside  the case in three nieces.

However, upon poking around and  testing, I discovered the perpetrator had added a pretty good automatic volume control.  This is a real improvement over just using the manual RF gain control when shortwave listening.  The 2E5 eyetube is dim, but does work as an S-meter.

I think I like it!  Stay tuned.


I ginned up a reproduction dial scale by scanning the broken one, and "tracing" it in CorelDraw.   I printed this on Hammermill White Window Decal stock (possibly and obsolete product), and stuck it to a piece of 0.01" clear plastic document cover.  It looks pretty go, but is not really translucent enough to let the pilot lights shine through.  I'm keeping an eye out for better material.  Use this "five-up" version when you commit to printing on the plastic. .
The dial scales on two of the sets were pretty faded, and they were for the bandspread coils.  I made a reproduction chart for the general coverage coils.  It's the right proportions for the chart frame, and you can print out a big one for actual use by "old eyes."
.
OK, time to get back to work!




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