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January 30, 2025. Low Power Consumption SSB Module.


Low Power Consumption Homebrew Rig for Use During PSPS. Prompted by the 4 recent preemptive "turning out the lights events" we are looking for the better mousetrap.





 

The Starting Place
  



One of the two G4GXO stages.

The 4X6 Board is a complete Receiver less the BPF, LO and BFO

Two of the G4GXO bidirectional modules (Jan 26th posting) are used in this rig. No RF Amp Stage is used to conserve power. What you see and hear is the antenna into the BPF and then on to the Mixer and IF Module. From there onto the Product Detector / Balanced Modulator and audio stages. The Rx/Tx Mixer is a TUF-1, and the PD/BM is an ADE-1. The LO/BFO is a Seed Xiao RP2040 driving a Si5351. The transmit chain will be a 2N2222A, 2N2219A. With 8 Volts PTP output from the 2N2219A that gives about 150 Milliwatts to the antenna on 40M SSB. If we could get 10V PTP then that is a quarter of a watt.

A small relay applies a set level of bias for IF gain on the 1st stage for Receive. On Transmit this stage is then the second IF amp and the relay lets it run wide open.

BTW, I am using a 3N209 in lieu of using the two J310's. A 40673 or BF991 would work well in this circuit. Forget the BF998 as it has too low of a Drain voltage and you would waste power using a voltage regulator to get 5 or 6 volts for operation.

What you see in the really short video is only a starting place. The current hog is the Juliano Blue LCD and the Seed Xiao RP2040. This needs to use something like a non-backlit LCD and the capability to turn off the display. A Pro-Mini MCU may draw less power.

I will take some current draw measurements and make a subsequent posting about those values. At 4:30AM, the garage is like a freezer as the OAT is 41F.

I braved the cold, and the Board draws about 300 milliamps on receive. The Digital LO and BFO plus display another 300 milliamps, so our starting point is to get that down to less than 400ma total. There are some three terminal voltage regulators and relays that draw lots of current and those too need a replacement.

Them that know can make it go.

73's
Pete N6QW


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