[Boatanchors] FBX alignment questions

[Al Klase]

Jim,

Maybe a little help, or maybe more confusion.  Hope the pix come through.
 From Radiomuseum.org:



Maye you can find a document that references the numbers.

I have one of these receivers, but the filter is different.



In this case, a rotary switch comes out the right side of the RX, and 
has 3 positions.  In the rear position it shorts the phasing control, 
the large knob on either.  But I can't find a clear schematic that shows 
two trimmers.



Not sure if this is FBX or FBXA.  Do you have the toggle switch, and is 
it "SPDT Center Off"?

Hope this helps a little,
AL

On 6/29/2025 1:50 AM, JAMES HANLON wrote:
> Hi folks,
>
> I'm working on an FBX, the version of the FB-7 with a crystal filter.  There are two variable capacitors accessible from the top of the filter box,  One I think resonates the transformer at the IF frequency, and the other is the Phasing control.  The manual doesn't say which is which.  Anybody know?
>
> Also I have a set of 40 meter bandspread coils and the A, B, and D sets of general coverage coils.  The detector coil for the 40 meter set has a trimmer capacitor adjustable through the front cover plate to tune the coil to the proper frequency, but the general coverage detector coils don't have that trimmer.  The manual says to adjust a trimmer inside the  receiver, on top between the tuning capacitor and the detector coil shield for maximum signal.  Is that one adjustment supposed to be good for all of the general coverage coils?  Or should I readjust it each time I put a different set of coils in?
>
> So far the receiver is coming along pretty well.  I have the National dog-house power supply with the proper 2.5 volts for filaments.  It's alive and receiving signals from my bench alignment generator on 40 meters.  I did have to shunt a couple of the resistors supplying plate and screen voltage to the BFO, which is now supplying ample injection for good CW reception.  And it is remarkably stable mechanically and drift-wise.  I hope to be making QSOs with it on 80 and 40 and perhaps even 20 soon,
>
> Thanks for the consultation and 73,
>
> Jim Hanlon, W8KGI
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-- 
ARK Sig Block Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/