thUndeadMod v3.4 - openLRS S**T just got real :)

[thundead]

I've updated the list of things I need to debug. Cheers.

[Coyote]

FW version: V3.5
RSSI Pin used: Pin 1
Hardware version used: V2
Band used:433 / 435
OSD Used: Telefly OSD
RSSI Buffer: Yes / No / Kind (lpf , opamp, resistor) Yes LM385
RX covered ?: No, bare PCB mounted in craft

RSSI showed 3.2v for first power up, now only shows 2.8v, tested with no buffer to multimeter, same 2.8 RSSI

[Coyote]

Update on tests, with hopping on 2.8v RSSI, no hopping 3.04 RSSI ( still short ) On 433 and 435

[thundead]

Think you might have a bad rx. could you check it against another one ?

Update on tests, with hopping on 2.8v RSSI, no hopping 3.04 RSSI ( still short ) On 433 and 435

[Coyote]

Update bud :

Interestingly, I`ve just fitted some tuned 459 antennas from Splashy ( Trevor ) and on 459 no hop, same rx is showing 3.2 RSSI

[thundead]

Hmmmm soo that means your 433 antennas might be  dodgy ?

Update bud :

Interestingly, I`ve just fitted some tuned 459 antennas from Splashy ( Trevor ) and on 459 no hop, same rx is showing 3.2 RSSI

[Coyote]

Ive replaced my rx antenna with a new 433 tuned one and full 3.2v is back :) However, if i leave it switched on my RSSI keeps dropping to 0.04 then back up. No failsafe initiates though ??

This is with 433 selected, static one channel

[papa_lazerous]

Ian I'd strongly advise you protect your Rx with some heatshrink at a minimum. Leaving it naked you are just on a countdown to when it goes wrong.  The processor on the top of the board is obviously static sensitive but the really important part is the RF module on the bottom of the Rx, use some heatshrink or cover/protect it with something else.  It may be entirely unrelated but I figured it would be a good idea to put it out there

[thundead]

here is a neat trick: while the rx is transmitting and all is ok, touch the back of the rx where the RF chip is located and It will lock and you will end up in failsafe lol. Really important to isolate the RX from anything else specially since it doesn't come with a case.

[Coyote]

Ok, sealed ( sort of ) rx in heat shrink, RSSI seems to ( 1 hour in ) hold its RSSI now, all be it 3.0v but its not dropping down to zero anymore

[papa_lazerous]

That's good to know.  What are you using to measure the RSSI at present?  The regulator onboard your Rx kicks out 3.2v and if you are measuring 3v odds are everything is fine and your meter might not be accurate. Whether you have caused any damage to the RF module by not protecting it is another matter.  Perhaps before flying do a low power range check?  Simply power up with the button pressed on the Tx to enter low power mode and expect around 200metres or so before glitches or fail safe and you know at normal power you will be ok....

[Coyote]

Using RSSI on OSD display and re-checked with multimeter which matches OSD readout is accurate

It previously had velcro stuck to the back of it, either way, with the velcro on the back, before it still held its RSSI and I did the ground tests and 3km flight with it like that. I think the first crash the previous flying day might have damaged my rx.

[papa_lazerous]

I think Velcro will have damaged it and this is why......  We all know how static electricity gets built up. You rub a balloon on your sweater and then it has enough charge to stick to your hair or even a wall.  Well Velcro has a smooth fluffy side and obviously the hooked side when they are together all is well but when you pull it apart you will create a very large amount of energy we are talking 10's of thousands of volts. And it's stuck ontop of the RF unit. A recipe for failure big time :(

[Coyote]

Good point, something I never considered

[papa_lazerous]

I'm going to do a range check before I fly this weekend just to absolutely confirm your issue is isolated.  I really hope it is