Lightning

lappydesktop
Posts: 15
Joined: Sat Jan 21, 2023 11:22 am
Location: Queensland Australia

Lightning

#1

Unread post by lappydesktop »

Hi all , whilst nothing can be protected by a direct lightning strike (Millions of Volts and Thousands of Amps) and i always nearly keep a eye out for any storms in this area that might be coming way before one can hear any thunder btw , so i disconnect any antennas and equipment , so a question if anyone knows .
Q= is there any form of static or relatively close (a few kilometers away) protection for lightning strikes like back to back diodes or a MOV or voltage absorber on the PCB boards of the SDRplay RSPdx? . as i have already mentioned i usually unplug all antennas and equipment when i notice a storm is getting close or approaching but it'd be nice to know that there might be something on the PCB anyway , i now have a new RSPdx and i looked at the case and really could not figure out how to open the case to have a look at the PCB to see what's there , any info at all would be appreciated , cheers

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KA1GJU
Posts: 212
Joined: Tue Aug 11, 2020 2:16 pm

Re: Lightning

#2

Unread post by KA1GJU »

I have videos of my SO-239's on my patch panel snapping (arcing over) during distant thunderstorms. The 160M inverted vee (no balun) is first to snap, then as the storm gets closer, the 80m inverted vee (again no balun) will snap. So depending upon the size (capture area) and balun or unun type (how they are wound) you may not get the build up of a charge.

Since I have remote TXR's nearby some of my SDRC Servers, I have been using these:https://www.arraysolutions.com/as-rxfep
Yes, you can buy some much cheaper ones on Ebay using lamps and diodes, but when you are protecting 4 Airspys HF discoveries on an active 4 port mulitcoupler, there's a lot of money
waiting to be turned into smoke. My Super Station #2 and KA1GJU@PCARC both use the above item to protect the fleet from nearby TX RF and lightning.

OTW I disconnect everything, USB cables, Ethernet cables, coax, 12Vdc cables, control cables from three locations when storms approach. I will watch the radar images closely to see if we are going to have a cell pass overhead. If more than 5 miles, I just sit a watch the two towers and wait for the inevitable. I've had two direct hits, and many close strikes. I have a box filled with blown up laptops, SDR-iq's, Airspys, SDRplays, ethernet switches, routers to show for the storms.

Looking at images of the SDRPlay DX, there's 4 screws holding the case halves together. Probably hidden under a large sticker? Just press around with your fingers over the sticker and feel for a small hole.

73 Kriss KA1GJU

lappydesktop
Posts: 15
Joined: Sat Jan 21, 2023 11:22 am
Location: Queensland Australia

Re: Lightning

#3

Unread post by lappydesktop »

Thanks for the suggestions regarding the dx case KA1GJU , i gather those screws might be under the 4 rubber feet and 1 day i'll take a look but at the moment i'm just flat out having fun looking about and listening on the RSPdx , i cant leave the thing alone and i'm lucky that i recently built up a new really fast computer (desktop) with heaps of ram that i can have open heaps of programs at the same time and its still barely working.

Antenna atm is a 80m-10m OCF , a 80m-10m L/C vertical awaits in the shed waiting to be put together .

I've also had plenty of others , long wires , NVIS and the likes and like you have heard and seen the ticking like a sparkplug even inside enclosed SWR/Power meters and at this area there is a lot of weather that creates that stuff , it's the season for that atm , 2 or 3 times real close direct strikes (7m away was 1 out of the blue no warning) it hitting the power pole out front whilst i was using a old FT200 during daylight , that one took out everything in the house permanently yet 5 minutes with a soldering iron the FT200 was back up and running , i was just about blind for a hour or so and had headaches for a few days with that session with Nature .

In the past i have used high ohms bleeder resistors across the balun (say 15-20k ohms) to alleviate static build up but as mentioned in the op a real close or direct strike would be generally Terminal so its far easier just to unplug Everything like yourself does .

So it looks like a wait now until i take a look at the PCB as i do want to know what or if anything is there just out of general interest , cheers .

jdow
Posts: 643
Joined: Mon Aug 10, 2020 8:17 pm

Re: Lightning

#4

Unread post by jdow »

Use an arc gap protector OUTSIDE, ideally where the coax first comes close to the ground. Create a plastic pipe wire hanger near the gap protector maybe a foot long. Loop the coax 1' to 2' diameter on that hanger and tape it in place. The inductance is a high impedance for the lightning. It's perhaps some help. Then repeat this at the house's wall. Ideally have a short section of coax to feed a patch panel where you can disconnect the coax and leave it dangling some distance from the house wiring etc. That's really good protection when you can disconnect the wires. (Do this for rotator wires, too.) Then inside the lower voltage protection tools become useful. In the bad old days a neon bulb across the wires knocked the pulses down to a less lethal 60 volts or so. These days there are other protection measures that should be on RX front ends that break down in the low single digit volts range. You can try back to back strings of 3 or more schottky diodes might work unless you have really large local signals. Then you might get IMD problems - and the diodes would still protect the delicate inputs. (At that point compromise noise figure and put in some real attenuation with 1W or higher ratings.)

If you dig, NASA has some excellent publications about this subject. They have some interest given that their favorite launch site seems to be in about the highest lightning incidence area in the country.

(I'm lucky in that regard here in the land of loonies called California. Southern California is a VERY low lightning storm area. I still looked into this and got paranoid when I first moved out here.)

{^_^}

lappydesktop
Posts: 15
Joined: Sat Jan 21, 2023 11:22 am
Location: Queensland Australia

Re: Lightning

#5

Unread post by lappydesktop »

Storms coming all week so just had to take a peek , PCB is a R7 (revision 7) , i did not measure the resistor but more than likely anywhere from 10K TO 15K ohm used to bleed off static charges , ant connector is the C/BNC one , cheers all as i can now rest in piece :idea:
Recovery Diode , https://datasheetspdf.com/pdf/1233269/WON-TOP/RS1B/1
ANT.jpg
Ant 2.png

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KA1GJU
Posts: 212
Joined: Tue Aug 11, 2020 2:16 pm

Re: Lightning

#6

Unread post by KA1GJU »

I'm curious as to how the RSP dx is affected by AM BC stations?
Do you see images of AM BC stations like I do on the RSP1A all the way up into 40M?
ie We have a powerhouse station +45 miles away on 1030kHz, but unless I put my DIY AMBC filter in line, I can see/hear it on 2060, 3090, 4120kHz, etc
The same goes for a 5KW station only 6 miles away on 1540kHz.

73 Kriss KA1GJU

lappydesktop
Posts: 15
Joined: Sat Jan 21, 2023 11:22 am
Location: Queensland Australia

Re: Lightning

#7

Unread post by lappydesktop »

KA1GJU wrote:
Mon Jan 23, 2023 11:55 am
I'm curious as to how the RSP dx is affected by AM BC stations?
Do you see images of AM BC stations like I do on the RSP1A all the way up into 40M?
ie We have a powerhouse station +45 miles away on 1030kHz, but unless I put my DIY AMBC filter in line, I can see/hear it on 2060, 3090, 4120kHz, etc
The same goes for a 5KW station only 6 miles away on 1540kHz.

73 Kriss KA1GJU
Hi , this is no sales talk or typing as i'll just report on what you have asked factually oky doky .

1st the 80-10m OCFD is a bit deaf down there on the BC band , its up around 15metre and flat with a commercial 1mhz to 30 1:4 GUANELLA balun/choke , when i mean a bit deaf one can hear and see the atmospherics drop as soon as one switch's to that band on any radio not just the RSPdx and typing that a local station 20klm (12 miles) away with a output of around 20KW los is 40 over , and north another with 60KW 45klm (28 miles) away los is 50 over both midway in the band here 864/963khz (9khz spacing down here) and on the SDRdx not a peep of any sign of them being there unless one clicks on them across all the bands and 2 spacing up or down them (18khz) there is just a slight bit of chatter using the 6khz filter but one can still hear very faint dx stations rolling in and out like i am now just to quickly test it out in real time (not from memory) .

I don't have much room here to play with now , i used to but a external new owner put fences up all around this block .

I think i have read that there is a function available called HDR (high dynamic range) with the RSPdx in which i have not even clicked yet as i have been spending so far all my time on the SW bands , i did a quick check/listen on the LW bands the other day just to see how it all was working and did not notice anything out of the ordinary regarding any inter-mod or images .

In the AMBC band here a few big power stations that have been around for years and years have shifted to the FM band and left the ambc leaving some empty spaces and its funny now that one can RX overseas stations there some with 3 or 4 broadcasting on the same channel like China/Indonesia/Japan/Png/New Zealand all rolling in and out at different times or at the same time and to think that they have been there also for years but one could never hear them due to the 100Kw (or more) local au stations (at night of course) .
I gather your Antenna might be the culprit? (being large and tuned) so the it'll smell those flea farts :D , ok that's all i can think of atm , cheers

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KA1GJU
Posts: 212
Joined: Tue Aug 11, 2020 2:16 pm

Re: Lightning

#8

Unread post by KA1GJU »

Well, that sounds promising!
Yes, the antenna is a 150' (46m) inverted L, 9:1 unun at feedpoint, +300' of 75ohm repurposed 1/2" (1.27cm) CATV hardline. Then the AMBC filter, 4 port multicoupler where 2 Airspy HF+ Discoveries, one SDR-iq and one RSP1A are connected to Super Station #2 server. Users rarely read what the server's capabilities or the SDR's capabilities are, I find random length EFW's seem to be useable for the full range of the SDR. I still see folks using the SDR-iq on VHF or UHF despite what I have entered in the radio choice selection. :roll:

I think ALL my SDR's are experiencing mild attenuation currently, we have snow/ice stuck to everything currently. It's raining lightly now at 34f (1c) to be changing over to snow yet again. Trees are bent over, as are the elements on my beams. Later today the wind is to pick up, so will be on genny power at some point. It's a winter wonderland for sure up here!

73 Kriss KA1GJU

PS Super Station #2 antenna is draped across the tops of the trees on the left had edge of photo, way out behind QRM sources of repeater sheds, and barn/shop.
Attachments
Taken after some of the ice has melted, 1/22/2023
Taken after some of the ice has melted, 1/22/2023

lappydesktop
Posts: 15
Joined: Sat Jan 21, 2023 11:22 am
Location: Queensland Australia

Re: Lightning

#9

Unread post by lappydesktop »

Hi , what sounds promising? and if you mean what i think you mean don't forget my commission :P

BTW i forgot to mention there is a MW/FM Notch button in the software also for the RSPdx and i assume one turns that on when listening above 3.6mhz just for an example if one has some AMBCB bleed over , it's actually enabled as it switches off/on but yet to actually use it (oh wait) , i did find out it works as 1 day back a few i went to the ambc band just to have another look and the SDRdx was behaving as if a antenna was not connected yet worked on all other bands , i spent a hour or so checking this and checking that looking about (i'm slow) then accidently looked up there at the buttons on the home page (i was looking about on all the other pages) and saw it and wtf! who turned that on (couldn't have been me :-) and turned it off and whalla the ambc band came back to life duh , hours .

I'm waiting for another so239/sma rg316 patch lead to turn up atm so i can use the 2m/70cm high gain collinear vertical and have that plugged in at the same time with the OCFD so no plugging/un-plugging to change antennas but for the local 2M repeaters even the ocfd picks up them real good imo not that there is much that is interesting on the local repeaters as out here the Cb'rs (Glorified Amateur Radio Operators) have crept into the hobby over the last 10 years and are taking over the bands even on HF (backtoyou :lol: the saying).

I too also use a EFw 10:1 RX (magnetic balun) the wire just fits in the block about 120ft long wire dedicated to the old FRG100 comms rx'er next to the bed , underrated antennas imo

Fine on the white stuff there looks cold , and no snow around here in this area at all , this year it seems the coolest summer (the opposite to you for the southern hemisphere summer here winter there) for a long time , last year and the one before that were relatively cool also , it's been generally up to 47c (117f) in this area in the past and 12 years ago minimums were -10c in winter still no snow , midsummer is nearly now and it'll be lucky so far to get over 32c Nice! , i would not mind seeing some snow about too btw .

Next purchase hopefully is another screen to match the one i already have just purchased a month or 2 ago for gaming (is one still allowed to game at 65?) , a 32" curved by gigabyte , there'll plenty of room on it with 2 side by side heaps more than the 24" i use atm for a 2nd monitor .

ok keep warm and cul

jdow
Posts: 643
Joined: Mon Aug 10, 2020 8:17 pm

Re: Lightning

#10

Unread post by jdow »

Um, ah, er, has anybody told you about high natural noise levels on HF and below, particularly below 10 MHz? All your 10-80 OCFD antenna does is shift the antenna pattern a little and overload your front end. On any given frequency if you are tuned off station and the noise level drops more than a few (single digit, low single digit) dB you have more gain than needed for that frequency. At 75M almost everybody can improve dynamic range almost for free by adding a 20 dB or even 30 dB attenuator to the antenna input of your receiver. You can dig around for natural rf noise on Wikipedia to find the graphs of interest. Also look up the noise figure calculation methods. Putting those two things together can give you an excellent clue about how this works. (Back in 1960 I spent some very precious money on a DowKey preamp. Nothing changed except absolute signal and noise levels, both by the same amount. I was angry. That drove me to learn more and an eventual degree or two. NOW I know why I was screwed.)

For something intellectually addictive get a copy of EZNEC and start playing with antenna modeling. It will give you a flavor of how your antenna is really working as long as your model is reasonably accurate and has 20 or more segments for a half wave dipole. All the various local conductors and lumps of metal will distort the results. And do use the real ground simulation rather than the (gross) approximations or free space modeling.

{o.o} Joanne

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