Re: Simple UBITX Test Set
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I can document what we use at HF Signals. But , in effect it is like this ...
1. We have a dummy load (20, 1K 2/watt resistors) and an Rf sniffer with a 10K and a 50 ohms in series. the 50 ohms goes to the oscilloscope.
2. A 10 MHz crystal oscillator with a trimmer to net it exactly to 10 MHz. we calibrate it every month.
3. A zener diode biased with 1 ma of current as a noise source. it amplified by two stage of feedback amplifier and feb back to the transceiver through the dummy load through a 10pf. there are two 1N4148 back-to-back diodes to prevent high RF from entering the noise amplifiers.
in rx mode, we can net the frequencies against the 10 Mhz oscillator.
the noise source allows us to set the BFO using the online BFO alignment tool.
on tx, we can monitor the RF to check for proper modulation.
We check it on 3.5 Mhz, 7 Mhz, 14 Mhz and 28 Mhz to exercise all the relays and LPFs.
A standardized way to debug a uBitx would be a big plus for this forum.