What is really interesting is SSB RX is over double the power consumption of RX CW! I wonder why as this is an SDR, presumably the DSP on the processor is asking much more.
Things don’t look so good with 20w SSB:
6.8wh RX + 40% 1.6wh = about 1aH from 11.7V lithium needed per hour of use.
I’m going to test this with an appropriate battery and a moutain to see !
Great little radio, I don’t want to start a KX2 vs FX-4CR debate here but radio defo has some advantages, provided you’re using resonant antennas !!!
Iq is the TX quiescent current i.e. with no modulation. (I’m not sure that the '817’s is)
BTW I have had the same issue that others have reported with pressing the knobs. I had to pull the knobs off and put an M2.5 star washer on the shaft to lift the knob ~0.7mm.
When you push down at the edge of the knob it touches the front panel, and so the press and turn operations are seem a bit erratic.
I also noticed some SMPS noise ~S3
This is every 200kHz. It is internal (i.e with a terminator on the input, and is also leaking out the power lead, so keep an EFHW away from the power leads
Also beware that the speaker and headphones outputs are push-pull. So the sleeve is at 2.5V. If you gnd the sleeve or connect the speaker pin to gnd, current >0.9A.
I was making a Kenwood/Baofeng adaptor (as the supplied mic is big,heavy and ugly). If you do, best to couple via 47uF, as you could easily plug into the spkr not headphone skt.
FT8TW seems to connect to the BT, but I did have to reboost it as FX4CR was not appearing in the phones pairing initially.
The new microphone was far too big 'n heavy for me to be taking away.
I have made an adaptor so I can use any common Kenwood / Baofeng microphone/speaker units, and/or Android (CTIA) earphone/mic units (4 pin type)
When both are plugged in, the Kenwood microphone is used, and the Android earphone is used.
To use Android microphone, use the RIT-PTT on the radio.
I use some 3.5mm 4 pin (TRRS) sockets with switch that I had
Beware: The sleeve of the Fx4CR Headphone and Speaker plus is at 2.5V not GND!
I just came back from a week tramping with the FX4CR. (5 Huts, 3 lakes, 3 SOTA peaks)
Before I left I tried it with my EFHW and the stock mic, and found that the stock mic had rf feedback problems on higher bands, probably with the PTT line I suspect.
I didn’t have any problems using my adaptor with either the tiny hand mic, or the mic-earphone set during my trip. (but due to band conditions it was all 40m)
Based on this I think the FX4 does not have quite good enough rf suppression on mic or PTT.
I will put an RF choke or bead with multiple (eg 7) turns in series with the both the mic and the PTT wires in the next adaptor. (btw I think the clip on ferrites being only 1 turn are for show, not function)
Signal reports are that my voice is a bit muffled on the FX4. I mostly used mic/earphone set, and the report was no sound difference from the internal microphone.
Using the RIT button as PTT worked well also.
Radio worked well for a week and had no issues that would stop me taking it again, but the only band that was alive was 40m.
The only issue is the (200kHz) switchmode noise, as the harmonics of the smps noise regularly drifted through 14.310 and 21.310 at S3+ when I was listening. If I have been using them, it would have been a problem.
The control logic was pretty usable for me. I found the memory arrangement where you don’t store permanent values but can retune them, was surprisingly useful in the way I use Yaesu QMB memories while operating.
The main annoyance was the U/LSB DIG mode where the audio is suppressed. When you also are using squelch this results in accidently turning the sound off.
Reverse protection is a shunt schottky diode across the DC input.
PCB design does not appear to have a fusible track zone, so an unfused reverse battery is likely to do substantial damage.
also:
External PTT input is directly connected to CPU i/o pin 53 with no protection or filtering whatsoever.
RF feedback on the microphone may be caused by incorrect filter inductor value on pcb next to mic socket (1mH “102” , instead of 10uH)
