Trial Run Results for Three Types of Whip Antennas

AnirbanSen

Member
The difference after adding a HDTV amplifier to my existing handy spider. The amplifier requires power from a USB source or 6V via coax:

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AnirbanSen

Member
I'm sure aliexpress has some 1090 MHz SAW filters you can buy.
2 SAW filters arrived today. Any tips on how to solder them onto a breadboard/Vero board?
There shall be 2 SMA connectors on each end.

But the filters are really small 4mm x 4mm. Let's hope I can find a semi professional who can actually get this done.

IMG_20190708_164937.jpg
 

ab cd

Senior Member
2 SAW filters arrived today. Any tips on how to solder them onto a breadboard/Vero board?
May be these diagrams will help. Terminal B is input, E is output. Terminals A, C, D & F are ground.

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wiedehopf

Member
Not sure how you would solder that onto a prototype board while maintaining a proper signal.
Managing high frequency signals on PCBs isn't trivial and to be honest i don't really have a clue about it.

Due to the small pitch you might want to put the chip on its back and solder tiny wires to the terminals.
Google dead-bug style SMD.

So i'll just wish you good luck, too bad your import rules didn't allow you to get the proper filtered LNA :/
 

AnirbanSen

Member
May be these diagrams will help. Terminal B is input, E is output. Terminals A, C, D & F are ground.

View attachment 2893

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View attachment 2894

I did come across some of your discussions from 2015. There seems to be some literature that says that the input/output must be orthogonal to each other. Also, the thickness of the board show be around 0.2mm (impossible to find).

Not very sure how it can be implemented but will try and wing it.
 

AnirbanSen

Member
Not sure how you would solder that onto a prototype board while maintaining a proper signal.
Managing high frequency signals on PCBs isn't trivial and to be honest i don't really have a clue about it.

Due to the small pitch you might want to put the chip on its back and solder tiny wires to the terminals.
Google dead-bug style SMD.

So i'll just wish you good luck, too bad your import rules didn't allow you to get the proper filtered LNA :/
Yeah, I know. The tiniest soldering I've had done is on the 555. This is way smaller. But let's see what happens. Need to find a board with 0.7mm strip width and that is a challenge as well.
 

wiedehopf

Member
You could just solder it between two pieces of coax without a PCB.

Basically you could fix a length of coax optimally with connectors to a piece of plastic or wood.
Then you just cut the coax open with a disposable blade maybe 2 cm. Just remove the top half so the center conductor is exposed.
Cut the conductor so you have a 1 cm gap.

Then you clue the filter upside down to the coax insulator.
With single strands from braided copper wire you can now connect the terminals appropriately.
Then you use a bit of copper sheet to close the gap in the shield if you want. Or some mesh.

Would probably be better than trying to get the 1090 MHz to play nice and go along PCB traces.
 

AnirbanSen

Member
Basically you could fix a length of coax optimally with connectors to a piece of plastic or wood.
Then you just cut the coax open with a disposable blade maybe 2 cm. Just remove the top half so the center conductor is exposed.
Cut the conductor so you have a 1 cm gap.

Then you clue the filter upside down to the coax insulator.
With single strands from braided copper wire you can now connect the terminals appropriately.
Then you use a bit of copper sheet to close the gap in the shield if you want. Or some mesh.
So the last 3 hours in making a premature attempt to see if center conduct can be connected directly. Whereas the first connection to the B terminal was successful, it went downhill from there with other terminals' solder bleeding to the adjacent terminal. I will see if someone can just solder copper strands or about 28SWG wire tightly to the terminals. I can carry out rest of the coax surgery.

How important is it that A,C,D and F all need to be connected to the coax shielding cable? The resistance between them is zero so they are internally the same.

See also: https://www.qorvo.com/products/d/da003143 (Page 3) and https://wireless.murata.com/pub/media/products/apnotes/an42.pdf
 

AnirbanSen

Member
This just arrived. So did the 20db inline amplifier. Specs say do not power in without load being connected.
Does that mean I have to somehow short my spider antenna somewhere?

Let's see what I can do this weekend.
 

Attachments

ab cd

Senior Member
This just arrived. So did the 20db inline amplifier. Specs say do not power in without load being connected.
Does that mean I have to somehow short my spider antenna somewhere?

Let's see what I can do this weekend.
You should not power in amplifier without connecting receiver (DVB-T)
(For an RF amplifier the "Source" is Antenna, and the "Load" is Receiver DVB-T).
 

AnirbanSen

Member
You should not power in amplifier without connecting receiver (DVB-T)
(For an RF amplifier the "Source" is Antenna, and the "Load" is Receiver DVB-T).
So what happens if the DVB-T gets disconnected? Is the duration of the disconnection a factor?

Anyway, after 2 months, finally, today the handy spider antenna was mounted on the roof. The pole was fixed a few days earlier. The radials have been also glued with a cyanoacrelate glue and the center covered with a silicon paste. After 1.5m of RG6, the F-connector connects to a lightning protector (not sure what type it is but it was about $1.05 on ebay. Not sure if/how it works. The protector does not have a DC block and my multimeter barely detects any resistance!
Directly connected to the lightning protector is the "RF IN" side of the amplifier I posted above. The other side of the amplifier, the Bias-T is connected.
Both the amplifier and the Bias-T is wrapped in an aluminum foil lined zip lock bag. This bag in turn is kept inside an old waterproof plastic lunchbox with holes drilled for wires each side. I'll send pics of this later.

Long cable all the way below (I am assuming about 36m have been used), the wire goes to the powering Bias-T and from the Bias-T, though a filter, the RF goes to the DVB-T. The Bias-T is powered by a 12V (13,5V DC) stepdown transformer unit capable of charging and using a 7AH 12V battery. The same transformer also powers the RPi through a 12V-5V DC-DC buck converter.
Strangely, the transformer sound gets loud when the DVB-T is connected and becomes louder when dump1090-fa loads. If dump1090-fa is restarted, the transformer sound momentarily reduces.
IMG_20190802_012146.jpg



IMG_20190802_012152.jpg

I'll check out this setup for sometime and then try out the inline amplifier and see which one is better.

@wiedehopf , I managed to buy another amplifier on Aliexpress which closely resembles the RTL-SDR. See: https://www.aliexpress.com/item/32847949227.html/ What do you think of this?
 

AnirbanSen

Member
Some quick questions:
i) When the DVB-T is connected to the power inserter, the entire RPi is likely to crash/hang. Even a ping to the Pi port stops immediately. The CPU of the Pi0W anyway runs hot. A pause and restart *sometimes* cures this. The htop log is below:
CPU[|||||||||||||||||||||||||87.3%] Tasks: 64, 73 thr; 1 running
Mem[|||||||||||||||||||||118M/480M] Load average: 1.67 1.61 1.49
Swp[ 0K/100.0M] Uptime: 00:25:23

PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command
372 dump1090 15 -5 27656 7284 2596 S 39.3 1.5 9:27.74 /usr/bin/dump1090
435 dump1090 15 -5 27656 7284 2596 R 9.9 1.5 2:26.17 /usr/bin/dump1090
3841 pi 20 0 8160 3032 2300 R 3.2 0.6 0:35.57 htop
457 fr24 20 0 106M 7584 4712 S 1.6 1.5 0:23.26 /usr/bin/fr24feed

ii) Sometimes dump1090-fa auto exits and stops running.
iii) Even when running, PiAware sometimes displays "
Problem fetching data from dump1090.
AJAX call failed (timeout: timeout). Maybe dump1090 is no longer running?
The displayed map data will be out of date. "
It could be that dump1090 is stressing the system. Not sure.

iv) Does the inline amplifier have a built in DC block?

Currently using the inline amplifier. Gain is set to - 10. The range seems have improved.

I originally intended to use the 1M-2GHz amp (earlier pic) for a few days after installing it yesterday afternoon. Due to better LoS at the roof, I got more aircrafts from all around, but the range deteriorated sharply. Today afternoon, I wanted to check for possible heat issues (there were none). However, somehow during the checkup, the amp got damaged and is probably kaput. (It could be that my unit below was sending out 13.6V and the unit is rated at 12V. )
 

AnirbanSen

Member
Some quick questions:
i) When the DVB-T is connected to the power inserter, the entire RPi is likely to crash/hang. Even a ping to the Pi port stops immediately. The CPU of the Pi0W anyway runs hot. A pause and restart *sometimes* cures this. The htop log is below:
ii) Sometimes dump1090-fa auto exits and stops running.
iii) Even when running, PiAware sometimes displays "
Problem fetching data from dump1090.
AJAX call failed (timeout: timeout). Maybe dump1090 is no longer running?
The displayed map data will be out of date. "
It could be that dump1090 is stressing the system. Not sure.
Reinstalled rtlsdr. Reboot. Stopped dump1090-fa. Test found USB dongle.
Then status check revealed:

pi@SenPi1:~ $ sudo systemctl status dump1090-fa
● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor preset: enabled)
Active: active (running) since Sat 2019-08-03 14:35:41 IST; 4min 3s ago
Docs: https://flightaware.com/adsb/piaware/
Main PID: 4794 (dump1090-fa)
Memory: 4.2M
CGroup: /system.slice/dump1090-fa.service
└─4794 /usr/bin/dump1090-fa --device-index 0 --modeac --gain 48 --ppm 0 --net-bo-port 30005 --max-range 360 --net --net-heartbeat 60 --net-ro-size 1000 --net-ro-interval 1 --net-ri-port 0 --net-ro-port 30002 --net-sbs-port 300

Aug 03 14:35:41 SenPi1 systemd[1]: Started dump1090 ADS-B receiver (FlightAware customization).
Aug 03 14:35:42 SenPi1 dump1090-fa[4794]: Sat Aug 3 14:35:42 2019 IST dump1090-fa 3.7.1 starting up.
Aug 03 14:35:42 SenPi1 dump1090-fa[4794]: rtlsdr: using device #0: Generic RTL2832U OEM (Realtek, RTL2838UHIDIR, SN 00000001)
Aug 03 14:35:42 SenPi1 dump1090-fa[4794]: Found Rafael Micro R820T tuner
Aug 03 14:35:42 SenPi1 dump1090-fa[4794]: rtlsdr: tuner gain set to 48.0 dB
Aug 03 14:35:42 SenPi1 dump1090-fa[4794]: Allocating 4 zero-copy buffers
Aug 03 14:36:59 SenPi1 dump1090-fa[4794]: weirdness: rtlsdr gave us a block with an unusual size (got 0 bytes, expected 262144 bytes)
Aug 03 14:37:01 SenPi1 dump1090-fa[4794]: Sat Aug 3 14:37:01 2019 IST No data received from the SDR for a long time, it may have wedged
Aug 03 14:38:02 SenPi1 dump1090-fa[4794]: Sat Aug 3 14:38:02 2019 IST No data received from the SDR for a long time, it may have wedged
Aug 03 14:39:03 SenPi1 dump1090-fa[4794]: Sat Aug 3 14:39:03 2019 IST No data received from the SDR for a long time, it may have wedged
lines 1-19/19 (END)


I am not sure if the power supply could have damaged even the inline amplifier installed late last night. Is there any way to test these?
 
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AnirbanSen

Member
As I diagnose further, I notice some strange things:
(i) Whenever the power F-connector is connected to the Bias-T, the RPi stops responding.
(ii) Something also happens to the DVB-T stick such that the stick itself hangs the RPi (as if some sort of infection) when it is connected it is just connected to the RPi (but removed from the Bias--T/MCX connector), - it still makes the RPi hang. Keeping the stick disconnected for several minutes appears to fix it.
(iii) When the system recovers (still being very sluggish), the above dump1090-fa status shows.
(iv) rtl_test -t showed that both dongles are otherwise fine when tested on a freshly booted system.
Using device 0: Generic RTL2832U OEM
Detached kernel driver
Found Rafael Micro R820T tuner
Supported gain values (29): 0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
[R82XX] PLL not locked!
Sampling at 2048000 S/s.
No E4000 tuner found, aborting.
Reattached kernel driver

(v) The issue occurred both with the test system (SenPi1 running Buster) as well as on the main system (SenPi0) running Stretch).
(vi) When the inline amplifier was used first time yesterday, it reported aircrafts from over 200nm away. But since then it has not responded at all. I am afraid after a long wait, this amplifier may have also been damaged. The ratings of this one are:
Frequency range: 950-2150MHz
Power supply: 15±3VDC
DC power passing:500mA(MAX)
Model: AP30
Return loss: ≥20dB
Gain (dB): 20.0±1.5

I originally supplied 13.6V (system rated at 12V). Today I have used a DC-DC buck converter to ensure a clean DC just in case my switching supply was defective having possibly blown the first 1M-2GHz chip. But I have no idea if the inline amplifier is still working. I had not used the DC block between the amp and the antenna for the first few hours. The Bias T is working fine will voltage only across relevant terminals.

All suggestions are welcome.
 

wiedehopf

Member
Measure if there is any voltage differential between the electrical ground of the RPi (usb port housing is easy to access) and the connection you connect to the housing or negative side of the bias-t.

There shouldn't be any voltage.
How do you connect the bias-t?
 
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