BC 221 Frequency Meter tidy up

[David Dunlop]

Rod.

On my meter, the 6 holes you asked about are where a set of solid head, hollow rivets secure the metal backing plate for the calibration chart booklet to the front cover.

You mention your charts are not matched to the meter so I am guessing somebody at some point went to a lot of trouble to remove the original chart book from the meter.

Hope that solves your mystery.

David

[Bruce MacMillan]

The 6 holes should line up with the aluminum backing plate to the calibration book, BC221a. BC221b is the crystal and it is mounted underneath at a right angle, much like the valve on the other side.

[Rod Salter]

Thanks, David,
Thanks, Bruce, I would have never dreamed that a crystal could be in a metal valve.
I have some old metal valves that have lost their markings and maybe with open filament
I may think of using one to make a look-a-like crystal or maybe they are the crystal
I will plug them in and see if they oscillate before commencing surgery

Visitor here this morning can make decals to apply to it

He can print, redo dashes, radio fronts and who knows what else

I had forgotten about his business as I hadn't seen him for 2 years
Apparently, he and his motorbike found a landcrusier running a red light, He got banged up pretty bad and only just getting about again

[Chris Suslowicz]

Some of the frequency meters had a full complement of spare valves in spring clips inside the case. A TS-174/U (the VHF version of the BC-221) I used to own came with a full set of spare valves and a spare crystal. (That was a big surprise!)

There was also a post-WW2 official power supply with a stabilised output that was a drop-in replacement for the battery cage.

Chris.

[John Mackie]

Hi Rod, VT76 is the same as 76 which has an octal equivelant 6 P 5 G also a rare beast. Good to see you have got it going. Re vibrator power supply problems, dont overlook thr buffer cap across the secondary of the transformer and sometims a second one across the primary as well.

[Rod Salter]

Here it is acouple of weeks (years) since I did this job
I got the 1000 k crystal in the last week
all good things come to those who wait