A Digital counter for the BITX20A

Allan Copland <acopland@...>
 

Hi Folks,

The BITX20A is a nice kit but some people might want to have a digital
frequency counter. Fortunately there is a simple, and cheap solution.

I ordered a Digital Frequency Counter from a Greek seller on Ebay who
programmed in the required frequency offset to display the correct
working frequency.

Jim's shop is at http://myworld.ebay.co.uk/jpl995/

The counters are competitively priced and require 40mv of drive so
I'd recommend adding a simple buffer stage between VFO and counter
so as not to load the VFO.

Although I haven't yet integrated my counter into the BITX20A, I have
tested it with my Philips RF signal generator and it works fine, as
expected.

The BITX20A has an 11Mhz IF. If you specify this, Jim will program in
the correct offset. His counters use BLUE LCD panels (16*2) with
back-lighting. The back-lighting is fed via a wire that runs from a
small PCB to the display, so it's easily disabled (or made
switchable). With no RF input, the counter reads 11.00000Mhz as
expected. The VFO frequency (3-3.35mhz)is added to this when
operating to display 14-14.35. The counter runs from 5V and has it's
own on-board regulator so it can run from a 13.8V supply.

Delivery from Athens was commendably swift.

73 Al.
GM1SXX

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