FrankenCricket - It's alive!
After Ozarkcon 2017, I ordered and received a Cricket 80 kit and stuck it on the shelf for "later".
The open board design was OK but I thought I might want to build one into a box so I ordered additional parts from overseas and from Tanner's (Carrolton, TX) on my occasional trips up to see the grandkids.
Recently I saw that the kit had been upgraded to the 80A, so I figured out the additional parts needed and after the most recent trip to see the grandkids had all the parts together and thought I could implement the new 80A circuit on the older 80 PCB.
Last Sunday, I opened up the Cricket kit, looked through the baggies of parts and realized that the kit had no semiconductor parts - no diodes, FETs, or IC!
NO BRAINS, the Cricket had NO BRAINS! Must have BRAINS!
Wait! I had a complete set of parts on hand for the additional Cricket in a Box project, so I did a BRAINS transplant to the PCB and after cutting traces (sometimes the wrong ones), swapping parts, bridging traces, and running new wires, FrankenCricket lives!
It puts out 1/2 watt and receives signals using several of the 80 meter crystals that I have.
I would not recommend modding the 80 PCB to a 80A. It really takes some careful planning of the trace cuts, new wires, and parts placement which I did not do well.
I used the 80A schematic for the build and found that D1 is reversed on the schematic.
The D1 cathode needs to be connected to the junction of Q4 & C18 to unmute the audio in receive properly.
I used an on-hand 68 uh choke for L4.
I used a small ceramic 22 pf trimmer for C15 to allow the receive offset to be shifted slightly.
I copied a couple of picture up to the files section, its not too pretty but it seems to work!
So be listening for a chirping Cricket from the bayous of Louisiana!
73 - Dave, N4ELM
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Nice work and thank you, Dave, for your report! I also have a 'unfinished' Cricket and maybe I will upgrade to the 80A level .... or maybe I'll just buy a new one! One thing that would be handy would a list of any new parts that are needed to do the conversion - it is always handy to have what you need already on hand.
Bob Groh, WA2CKY
On Tue, Dec 5, 2017 at 10:06 AM, n4elm@... [4sqrp] <4sqrp@...> wrote:
The polarity of D1 is shown correctly on the 80A schematic. The diode is used to extend the muting action after the key is opened to eliminate clicking in the headphones.
73 Dave NM0S