My new construction and design "full duplex" transverter to operate via HF TRX.
Based on frequencies mixing. 2 separated VCO units, each one controlled by single PLL & reproduce single frequency. Basic control program for PLL2 may changed by re-calculation of counters value, there may working on any amateur HF-band from 3,5 to 28 MHZ.
The design allows the use of SDR dongle and an external reference OSC in range of 8 ~ 20 MHz. design does not include driver stage for transmitter path. Every chnge required re-programming PLL controllers.
In attachments seams partial construction. At last tested PLL's lock after debuging firmware for burning controllers. Repeated experience with PLL's lock gave a positive and identical result.
All stages of design maded by my self , from idea, include program writing and burning controllers , loop filter calculation, pcb routing, parts ordering and soldering.
Total box size 100x56x24mm.
Now partial explane about block diagram.
Main synth lock VCO at 1660,5 MHz, second PLL do it at 949 MHz. PLL1 serve downconvertion operation for product of 711,5 MHz. By the way this frequency will change final downconvert to any HF band. Mixer connected in those manner not given so mutch on 2609 MHz, also LPF 720 MHz disable it, especially IF max range is 1500 MHz.
Next converter is 1660,5 MHz mixed with 711,5 MHz. This point serve RX or TX mode. If mixer M2 is "shorted", no product of up conversion can run trouth this path - there M1 receive signal from LNB and mixed product going to the owner TRX.
In TX operation mixer M2 is up converter (IF port at input) with 1660,5 MHz and product of M2 - 711,5 MHz. Last converter based M1 mix transmitter carrier from TRX and product of M2. Here i'm set power attenuator from TRX to prevent damage of mixer M1. Maximum saturated power to RF port is 0 dBm.
Input-output path's signals distribution diveded by diplexer - LPF for LNB in and HPF for PA's driver.
Abouth harmonics or products from mixed signals.
949 x 2 = 1899.
1899 + 711,5 = 2609,5.
949 x 3 = 2847.
1660,5 x 2 = 3321.
1660,5 + 711,5 = 2372.
711,5 x 2 = 1423.
1423 + 949 = 2372.
711,5 x 3 = 2134,5.
There is no product of combinations above is close to 2400 MHz.
About x-harmonics of 28 MHz not discuse.
Even i'm not shutt down PA and driver in RX mode, nothing to amplify bacause mixer M2 is "shorted". In any case, port's short technics used in frequency doublers based mixer.
Final stage will have BPF for 2400 MHz, but i not support any PA, also not support BPF/LPF for the range.
Both VCO's choosed with low RF output power, to prevent high level radiated power into system. For PLL' f-in port low power arround -3 ~0 dBm found in working windows range. Actualy real RF power of VCO is lower than datasheet value.