[ARC5] Request for help, aligning BC-453-B.

[Kenneth G. Gordon]

On 28 Jan 2015 at 19:26, Leslie Smith wrote:

> SETTING THE MAIN DIAL.
> The "pip" on the main dial was broken, so the in first step I set the
> sig gen to 500kHz, and tightened the nut holding the main dial.  Maybe I
> should have done that at 200kHz, not 500kHz?

That would only work if the receiver was already aligned. You will have to 
use the "equalize the ends" method to set the dial, unless you can replace 
the missing pin, and find the original tiny hole in the dial...which is almost 
always covered with paint. It is far easier to find that tiny hole by looking at 
the back of the dial. Even then, it can be missed the first time you look for it.

> ALIGNMENT.
> According to these documents, I align C4E at 520kHz (that worked)
> At the low end of the band I touch C-9 at 210kHz.  (Here is my trouble.)
>       <--- TROUBLE HERE --<
> 
> Here is the problem.  I always understand alignment touched 'caps' at
> the high end of the band, and coils at the low end of the band.  That's
> not what this book says.  It says trim C-9 at 210kHz.

Yes. See below. You cannot adjust any of the coils. Once set at the factory, 
they were fixed in place, although they DO have adjustable slugs in them.

>  OK, When I swing
> C-9 from max to min pFs, I change the frequency very little.  If I set
> the '453 dial to 200kHz, my signal generator reads 191kHz.  In other
> words, at the low end I'm almost 10 kHz 'off'.

C-9 is in SERIES with the coil, so it, essentially, does the same thing as 
adjusting the coil.

>  Maybe I should have set the dial at the 'bottom' end (200kHz) and then
>  trimmed at the top end of the dial?

Your problem is that the dial is not set correctly. First, you should try to find 
where that "pip" as you call it was originally installed, and then install a bit of 
cut-off sewing pin there, then find the very small hole in the dial, and mount 
the dial accordingly....IFF the dial you have is that which was original with the 
receiver.

If the dial you have is NOT original to the receiver, you will have to go 
through the exercise that someone else mentioned here by equalizing the 
two ends of the dial with the cap fully meshed, then fully un-meshed. That 
will get you close, and may even be almost perfect.

When alignment is correct, the various frequencies to which you tune over 
the majority of the dial will not be off by more than the width of one of the 
lines engraved on the dial. Readout was unusually accurate for the time. 
Tuning may be "off" a bit more at the extreme ends, but not enough to worry 
about.

Ken W7EKB