BC221 Window

[pwdrive]

Anyone ever replaced the plexiglass window on the BC221 frequency meter?

Edit: The one that covers the logging scale book, mines cracked.

Lawrence.

[Skywave]

I see you've had no replies , so here are a question & two suggestions.

Can you do the necessary dismantling to remove the glass? If so, it should be possible to get a replacement piece of glass cut to size. Failing that, perhaps a piece of clear Perspex would do the job?

Al. / Aug. 2, 2013 //

[pwdrive]

Hi Al, it's Plexiglass (US term for Perspex) the problem with replacing it is not obtaining the Perspex itself but getting the old piece out, it's clamped between the front drop down panel and some strips of stuff on the rear, the bug is that there are a total of 18 rivets securing it, bit of a job.

Lawrence.

[Skywave]

O.K., Lawrence. Regret that I have no experience at all of that instrument. I also did not know that Plexiglass = Perspex. But I do now.

Al. / Aug. 3, 2013 //

[pwdrive]

When I get time Al I will take a photo of how the Perspex is fixed to the unit.

The BC221 is very well engineered, the quality of the construction is superb, considering when they were designed the frequency accuracy is very good indeed when up to spec. As you probably know it's a hetrodyne jobbie, the tuning drive is first class, the frequency is referenced from the logging booklet which contains the frequency refs for all the tuning dial settings.

Made in large numbers by various US manufacturers for the WW2 contract.
The one that I have was made by Allen D. Cardwell of Brooklyn, NY.

Lawrence.

[pwdrive]

Here are some pics Al and anyone else that may be interested, 'scuse any fuzziness, cheapo camara and crap photographer.....

Two pics:

Show the rivets securing the Perspex (Plexiglass) I'm no engineering expert on rivets so I don't really know what type they are, the dome head is very shallow, they appear to have some form of "anodized" ? coating on them as they are almost black, would they have been part semi tubular rivets?

Some other pics:

Showing the front cover of the frequency logging booklet, note that the serial number on the booklet is the same as the serial number on the ID plate on the unit that's shown in another picture.

If anyone wants to obtain one of these units it's important that the serial number on the booklet coincides with that on the ID plate on the unit otherwise the accuracy will be non descript....

A pic of the controls, there are two scales, one on the main dial and the other in the vertical window to the left, the photo reflection has obscured that scale somewhat.

Pic of the logging booklet open at the first page showing logging scale numbers versus frequency.

Lawrence.

[AlanBeckett]

You're right Lawrence, David Bailey you ain't
Is the second picture the inside? If so then they look like hollow rivets with the Perspex protected by a metal strip. They'll be pretty thin on the ground I suspect. It would be possible to make some, but a bit delicate.

Alan

[pwdrive]

Thanks Alan, yes the inside is the picture showing the metal retaining strips, not sure how to tackle this one if I ever get round to it.

Options thus far considered:

A) Leave it as it is.

B) Drill out and replace rivets with same type and colour (highly unlikely to find any)

C) Drill out and replace with the nearest rivet equivalent (that will do the job but won't look the same)

D) Ditto...screws and nuts...(ditto)

E) Break out all the perspex, slit the rivets, remove the metal clamping strips with rear of rivets still attached, fit new perspex in (glue) glue back retaining strips, if I can do a clean job then job done and will still look the part.

F) Sell it saying that the crack in the perspex was from a glancing blow from a stray bullet when in action.....

Lawrence.

[Skywave]

Being the devotee of nuts 'n' bolts that I am, I'd chose option B to start with then option D. It will then not look original, but then any other repair then becomes much easier. I'd also use brass screws - purely for appearance.

Al.

[AlanBeckett]

Actually they are available - http://www.ebay.co.uk/itm/25-X-8mm-LONG-...upplies_MJ&hash=item5882ea5191 or at least similar ones. I'm assuming they're 1/8" or 3mm.
Dial Hollow stem rivets into ebay.
Alternatively you could use Bifurcated Rivets with Washers.

Alan