Geoff S Posted October 11, 2020 Share Posted October 11, 2020 I haven't been flying at our usuall site for several months for personal reasons (Covid based) but today had pleasant weather and light winds so after my morning walk I decided a quick couple of flights in a nearby field would cheer me up a bit. I took my Liddle Stik and, despite initial concerns that the grass would be too long to take off, the recently departed sheep had done their job and I was in the air. However even when I was still fairly close in I began to get RSSI warnings so, after a couple of circuits, I landed. I then did a range check (as I should have done first, I confess) and it was poor. I checked the connections to the X8R with long range aerials and they were OK. A further range check when I walked all round the model (an advantage of having a totally empty field at my disposal) I found that I could affect the RSSI reading by adjusting the angle of the transmitter. My first thought was that I'd disturbed the connections to the Horus internal antenna when I replaced the backup battery a few week ago but they looked OK. Then I checked that the internal antenna was the selected option. It took a while to find it (it's in the hardware/calbration section rather than the radio set-up one) and sure enough it was set to 'external'. Changing that cured my range problem. What worries me is that it had reset without my doing anything. I've never used the external antenna because the internal one works perfectly well over the range I need and until today have never had an RSSI warning of 'critical'. In fact it's amazing how well it all worked without an antenna at all. I've changed the options to 'Ask' so each time I select a model I have to deliberately choose 'internal'. I know I should have done a range check before flying but I didn't. I last flew about 3 months ago and everything was OK. It just seems strange that a setting should change without warning. Geoff Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted October 11, 2020 Share Posted October 11, 2020 As a matter of interest Geoff, which Horus is it, the 12 or 10? Ah, forget I asked, just checked previous posts by you and it's the 10! The only reason I ask its that the 12 has a bad internal design which can lead to a shielding of the internal aerial and I was advised to use an external one! Edited By Ron Gray on 11/10/2020 21:20:18 Quote Link to comment Share on other sites More sharing options...
Geoff S Posted October 11, 2020 Author Share Posted October 11, 2020 Yes, Ron. It's an X10 standard and normally the internal antenna works perfectly. Geoff Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted October 11, 2020 Share Posted October 11, 2020 I recall reading somewhere that someone had done some tests and come to the conclusion that the internal aerials were best. Certainly I've not had any problems using the internals on an X10S. Many years ago, when I was developing my 459 MHz set, I did build a PCM version, and because it had a failsafe (and I was flying a trainer / semi free-flight model!) I tried removing the Tx aerial in flight. I still had full control at a height of a couple of hundred feet and probably two or three hundred yards! All from leakage from a BNC connector! However, I do not recommend doing this! It is very easy to burn out the output transistors! I don't know if the chips used in 2.4 GHz transmitters have any kind of protection from high SWR, but if you have access to a power meter of some kind, it might be worth checking your output from the external socket (should be 60mW). The model settings in an X10 are stored on the SSD card (non volatile memory), but the fact that it has a backup battery implies that it also has volatile memory for some functions (just like a computer's BIOS settings). Removing that power would probably cause it to drop back to default settings. Often they have a capacitor which can maintain settings if the power is lost briefly, but if you took your time replacing the backup battery, it might well have caused some settings to go to "default". Might be worth having a look at some of the other radio settings and just checking! The time-of-day clock is usually a good guide on a computer! It might be the same on an X10.... -- Pete Quote Link to comment Share on other sites More sharing options...
Geoff S Posted October 12, 2020 Author Share Posted October 12, 2020 That's a good point, Pete. The problem is, in these very unusual times, I can't remember if I've flown in real life since I replaced the RTC battery. I suspect not. The clock was incorrect before I replaced the battery and I reset the time and probably the date. Model data are stored in a non-volatile micro SD card so wouldn't be affected but I suppose system radio data (possibly including choice of antenna) could rely on the battery. The external antenna connector isn't a BNC but it's similar and I was surprised (and lucky) I didn't lose the signal completely. I was able to get a zero RSSI reading with the transmitter in some attitudes when I did my walk round range check at about 25 metres (in range check mode). Anyway, it''s worth bearing in mind when the RTC battery is replaced. I suppose, if were truly a thorough investigator, I should remove the battery and see what data are reset but it's such a hassle i don't think I'll bother. Geoff Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 12, 2020 Share Posted October 12, 2020 The OpenTX developers over on RC Groups are adamant that the RTC battery really does only maintain the Real Time Clock - hence the acronym! I've not noticed any models on my X10 defaulting to external, but I bought a 50 ohm dummy load off Ebay and fitted that to the external aerial connector to protect the output stage just in case. As a point of interest (possibly!) I used to use DFT modules in Futaba transmitters. One day I was flying circuits with a Hangar 9 Texan and kept getting RSSI warnings on the far end of the circuit. It was only after landing that I realised I'd been flying without the aerial being fitted on the module. I guess the airborne range was 150-200 yards, maybe more on occasion. Quote Link to comment Share on other sites More sharing options...
Geoff S Posted October 12, 2020 Author Share Posted October 12, 2020 That's what I understood, too, Bob. However something must maintain the non-volatile memory that stores radio data (rather than model set-ups). Whilst fitting the new RTC battery I also had the main battery disconnected for some time (probably over an hour. It was the first thing I did after removing the back) so that may have caused it. I successfully flew yesterday afternoon without an aerial but probably no further than 150 metres away, if that. I only got RSSI warnings a few times but I landed quite quickly when I did. A dummy load is a good idea. I'm not sure what the aerial connector is called. It's certainly not a BNC type. Have you a link for the one you bought? Geoff Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted October 12, 2020 Share Posted October 12, 2020 They are called SMA connectors, but be careful as there is more than one type! Different radio systems use the different types, and you can end up with no connection! Usually, the transmitter has the threaded bit and the aerial has the "nut" that screws onto the Tx (if you see what I mean!). However, if you look inside the connector, you will find that the central pin is on the aerial end on some makes, and the Tx end on others! If you try and connect two "sockets" together, you end up with no connection! I'm not in my workshop at the moment, but I seem to recall that Spektrum are the opposite to FrSky! Be careful! -- Pete Edited By Peter Christy on 12/10/2020 12:29:10 Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted October 12, 2020 Share Posted October 12, 2020 The radio setup data is also kept on the SD card, openTx (and erskyTx) do not store any setup or model data anywhere else. Mike Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 12, 2020 Share Posted October 12, 2020 I used one of these, in my world it is female SMA even though it's described as male! Quote Link to comment Share on other sites More sharing options...
Geoff S Posted October 12, 2020 Author Share Posted October 12, 2020 Thanks, Mike. If that's the case I wonder why my antenna selection changed because I'm 99.9'% (no-one's perfect ) sure I didn't. Thanks, Bob. I'd been doing a search myself and ended up on the same site! Again there's confusion as to the terminology of male v female connectors as on a recent thread. It's described as 'male' because of the housing as the seller confirmed when I asked. I've ordered one even though the spec only goes up to 1gHz - it won't do any harm and it may save an output stage. It'll look better than the supplied plastic cap anyway. Pete: The antenna has a pin in the centre. I checked before looking. Geoff Quote Link to comment Share on other sites More sharing options...
Geoff S Posted October 14, 2020 Author Share Posted October 14, 2020 Very good service from the eBay pointed to above. He replied immediately when I queried the gender of the connector. The dummy load arrived this afternoon by first class post. I was very surprised as postage was included in the £2.95 price. It looks quite neat. Certainly better than the yellow plastic cover provided (not that it's big deal from an appearance POV). Geoff Quote Link to comment Share on other sites More sharing options...
Graham Foster Posted December 21, 2020 Share Posted December 21, 2020 Re the debate about aerial choice on the Horus 10: Maybe the answer will expose my lack of know edge of Open TX but anyway. I installed a RX6R Rx in my new glider and all worked OK until I checked the range. On the range setting I was only getting 15 paces before RSSI Critical. I thought maybe it was because of the internal aerial but when I installed the external aerial I got the warning “Make sure aerial is installed” The aerials on the plane are over 30cm outside the fuselage. Isit me or do I have a fault on theHorus.? Quote Link to comment Share on other sites More sharing options...
Geoff S Posted December 21, 2020 Author Share Posted December 21, 2020 First, are you sure you've selected the internal antenna? In my case the external was selected when formerly I'd set it up to use the internal. Consequently, as I hadn't fitted the external antenna, I got RSSI warnings when I flew. I was surprised how well it all worked without an antenna at all, as I guess the maximum distance was around 70 to 100 metres - it's a big field. Second, if you're walking away when doing the range check the RSSI warnings can come after a short distance as your body is blocking the transmision. Turning to face the model restores signal strength immediately. Third, in order for the external antenna to work it has to be selected. After my little problem I've set up my Horus to select which antenna to use each time I select a model. Geoff Quote Link to comment Share on other sites More sharing options...
Graham Foster Posted December 21, 2020 Share Posted December 21, 2020 Thanks Geoff, I had selected the internal antenna. I have to confess I flew the model before doing a range check and got RSSI Critical with the plane about 50m away (It’s a slope soarer) Ilanded immediately and did the range check Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.