Deshibo GA450 test and flaws

Long after looking on a decent loop antenna for external receptions with the PL330 and while looking on Youtube i found this interesting loop. it is intended to be used in my now primary house on the outskirts of the Mt Olympus . The reason is due to many reasons: 

There are some significant local noises coming manly from a mobile cellphone antenna and another unknown source . The one is heard as ignition type while the other as as like a shift carrier mixed with some noise

Wishing to get better in the results of other vloggers  i have made a playlist. this playlist has been watched a few times before making the order
 

I have also noticed that the circuit introduced  some 'router noise' as i cal call it 

It is a shifted or freq agile noise carrier. It  sounds as shifting buzzer as heard before the 2018 when my main radio was a ICOM R75.  In SDR spectral view it is shown as an unstable  noise carrier. most people advised that this is the problem if the stepped transformer available in ALL routers of the trade . Here is a photo as grabbed by one remote kSDR: 

--End of topic--

in just 25 days i have received the parcel with a box typical to this product

This is what is included into the carton box: the loop antenna , he active loop tuner on the left and three cables: BNC-BNC jumper  for SDRs , BNC-3.9  for shortwave radios and a USB C type adaptor cable 

Plus a mini guide to in both Chinese an English and several afrolex leafs 

The usage is very simple IN just seconds you can connect the metal circle into the base via the BNC plug socket and use one of these two cables to connect into the radio receiver or SDR. 

  IN work!

Its usage is very simple : Just turn on the pot and tune to to the desired frequency. in contrast to what i expected the antenna starts from the higher parts of the SW band and gradually tuning lower. The inside of the pack includes an  active tuner that produces a frequency dependent Q with peaks as high as 20db in he 5 MHz.And more important the battery was drained when i  tested the loop fir the first time. I had to immediately charge it with the  cable included in the package

After long usage in just two hours i found it having several flaws. Im sure that it has noe been passed for control quality otherwise the QC could to put ot in the junk 

 --------------------------------------------------------------------------------

IN short these are my findings

Using radios  (list not noticed in the video )
-High noise is introduced with power on
-Circuit leaks at power off. Conveyed and audible via the cable to any radio
-Strong spurious signals adjustable by the potentiometer
-once switched on there is a strong annoying noise from the loop circuit
-The tuning SNR is  lower than radio's telescopic antenna!
-Rotating the loop 15 degrees clockwise from the circuit box axis can remove most of tuner noise The female BNC base is a bit loose. 
-I Prefer to rotate the whole system for removing the noise. this si the only part that works OK with this system !
-BY chance scanning on the MW band i found a typical 'router noise' existing on 15xx kHz with switch off

 

The proper loop angle to cut circuit's inner noise

Also  noticed with my SDR:
-Low Q in the top of the band Zoomed out can show hundreds of spikes most of them are from my PC .At least 3 meters far are needed to get rid of them.
-Two Image  peaks while tuning the circuit  in addition to the tuning peak-as i tuned below the 8 MHz or in 7-8 o clock
-Tunes only between 4.36 to 20 MHz .
-Harmonics up to 90MHz (!!)

Radios used : PL550 / PL330   and RSP1a SDR

And a few more screenshots :

Here si the SDR equivalent for the power leakage while the antenna tuner is turned off. I can find these 'noises' while using any radio with ATTenuator OFF  These signals are quite low

The lowest tuned frequency is around 4.3 MHz ,The Q could be very high and with very narrow bandwidth. this is also part  of the noise  transmitted by the router[s] from the 7 floor building. A short search can show a least 12 routers !

 Some closeup on the higher part with some test details
 

This is a scanner picture that shows the harmonics produced by the antenna tuner in the position of "6 o clock" Please Left Click for watching the full sized screenshot  

________________________________________________

I have made a few videos posted in my Youtube account and also notified the seller for these problems. He responded that the company is off  due to a national feast so i have to wait sometime.

https://youtube.com/playlist?list=PL9gILW4OYgSEU4bNWIGP-ULt9AMbTOT2v

The first 7 videos are my own  3 made on as 4/6/22 with SDR in mind on the centre of the city while 4 more added on 7/6 in a more clean place .

The above  list was also posted before 4/6 in the comments under the remain vloggers pages for asking comparative results. After 5 days I received the first reply:

Hello My Radio Friend,
You should try your GA-450 antenna outdoors it is quite sensitive to QRM indoors.
I tried it on several Sony ICF-2001D, Tecsun PL-880 receivers outdoors with no problems.Indoors on my Vintage receivers it depends in which room of the apartment I am located.
I live in a building from the 1960s, in a small town and a trial in the countryside far from sources of electrical pollution would be worth trying.
Maybe also, look at the side of the computer power supply, sometimes switching power supplies create disturbances...
Try to put several ferrite cores on the coax of the antenna and on the cable of the PC...
Well, I'm really sorry that I can't give you more information about these problems.
Let me know if going outside solves these problems.
I wish you good luck, 73's, Friendships at the Household and see you soon.

Indeed he was right only for one : the sparks. Just putting the antenna around 3 m far from  the laptop the sparks nearly diminished but all other 'flaws'  remained. I can believe that the item didn'y pass the QC I will also follow his guidance to do the outdoor test  

________________________________________________________________

Update:not so much later I have bought a new one from amazon de  that  form a Chinese seller but different from the above . It came in just 11 days . I immediately tested the battery before operating it. It was also drained as with the previous pack.  I left the interface charged for around  15 minutes an immediately made my comparisons. The first  was to check what happens with the interface in medium waves

In short the loop operates quite better with the same noise level as the first but: 

• Q levels are quite lower than the first with up to 25 db of gain That means also that the tuned bandwidth is broader.  (2.5/5)
• Noisy as the other after switching ON the interface (2/5) I think that they have replace the FETs with other model that has lower internal noise.
  
• Lowest frequency is roughly the same at 4300 kHZ (OK)
  
• The interface in off duty produces high noise on MW that covers all the MW band Once again the interface leaks unnecessary battery power and can drin it in short time (2/5)
• Does not tune on MW but as loop it can remove nearby noises,  (4/5)
  
• The RSP spectrum analyzer shown NO harmonics above the 30 MHz! (5/5)
  
• In short the loop is quite better with minimal problems comparing to the previous.   Objective Verdict 3/5  but comparing to the previous yields 4/5 

 

• MY  proposal is : (1) replace FETs with others with lower  internal noise (2) recheck all stages for any power leakage.
  

Full  visual report is here - no comments just tuning the SDRplay across the bands It is also added in the playlist mentioned above: 

https://www.youtube.com/watch?v=cQcxIQz4mxM

I m now thinking to return the first loop for the quest of money.

 

 --------------------------------------------------------------------------------

 

Two days after thinking to return the first loop i tested it once again. I fist charged the interface for around 15 minutes as the time passed and he inner system leakage drainer its battery. Immediately used the   SDR uno as testing program

i was very well amused that the loop behaved exactly as the second! Checking if i used a wrong interface was mistake as in the firsrt loop  i used a tape marker to separate from the other - no tape-

I really wonder what this can mean ... it that behaving as ...human??  

the only  minus is the strong noise introduced by the circuit

Short review for the Youloop antenna

The Youloop antenna has been bought via the official site of RTL SDR in ebay.It has been received  without any problems in the standard Speedpack time of ca 15 days. I waited a few days more when i returned in Thessaloniki two weeks after. 

It has been tested with the Airspy HF+Discovery   and its 2 m cable. 

interesting to see is their dimansions !

Reception on the bands above the 15MHZ is quite very poor: System   threshold is ca -150dbm  with signals shown in the band with n more than 20 db SNR These stations re usually heard strong with standard radios as PL330 or PL550 fron Tecsun

The above copy  is made with my SDRConsole, my most prefered program  for making SDR reception. S units and  dbm levels are the standard method to evaluate signals . Notice also the spurious nd self generated  signals that recur in the band

 

Airspy in contrast 'zooms' the signal ie tunes better with its counterpart antenna (Youloop),   I cant prefer using Youssef's program (SDR#) as it is not well normalized as the SDRConsole. This program that suits much better for scientific research. As far as I remember it has all the whistles and bells to so  a more serious  and scientific signal analysis work (signal history analysis, 3D , multiple audio recordings etc just look at )

a few interesting hints by using it

(1)The door nearby the mini PC  (laptop) has the highest signal indoors! It is one f the few points where the noise is very low with levels of 15+ db as shown in the radio signal level readout . Antenna hung in the door with a 'cloth hanger'. Turning this door cold remove most of the local noise and offer also cleaner reception :

https://youtu.be/qdCYASiJWck  my mom helped me to turn the door!

(2) Outdoor reception offers higher signals and SNR . Correctly rotated antenna can also remove nose to the 20db level except router noise. More than 12 routers can be detected with my smartphone in this building .The range  effected is 150-1200kHz - partially-  , 3-6.5 and  8-11MHz

https://www.youtube.com/watch?v=pycoPZ6Aquo

detailed info with photograph Just click on the photo to see beter:

(3) HF+D can also be overloaded with this antenna . N Greece is flooded with more than 15 signals [er band of S9+20-40db on the 49, 41 and sometimes 31mb

https://www.youtube.com/watch?v=yZWj0Is6beU

What i didnt like  with the antenna's  metalic hardware : this  antenna will be used for Dxpeditions with some temporary use per event These connectors require very careful usage and for sure they can easily break. If  the box could be could be a bit bigger/sturdier  ass their  competitor I wold feel more safe for more everlasting usage 

I would also like if there would be a more permanent system design.

IN the VHF band the signals are better that  i could expect ....I found this video useful:

https://www.youtube.com/watch?v=u-TbWOPP-cQ&t=1s

I m generally quite impressed with this antenna  in the lower parts of the HF scrotum.
I now think to use it outdoors that is adding modifications on the support , extending the cable and possibly add an LNA near to the loop.. 

 ========

Update: testing with standard radios

I added  a SMA-3.9mm mini jumper after the antenna lead  and used: One  analog PL550  and the DSP PL330 radio. Both are from Tecsun.  Results are as follows:

-PL550 good and deep nulls
-PL330 not so deep nulls 

https://www.youtube.com/watch?v=lCv0m6mzghU

..with PL550 only.  Antenna's shadow  in shown in the chair the time i turned it back and forth . Notice that most of the noise is automatically removed thanks to the ANC - auto noise cancelling - a feature that is built in on my smartphone

The new loop experiment

 Much long after designing an experimenting with wire antennas i decided to experiment with a Moebius antenna  design similar to the the home made youloop design as shown in the swling page 

Instead of the R58  types of cable I used RG6  the standard cable used for TV and satellite antenna lead that was very  handful together with some wire benders zip ties and cable terminals I used also the soldering probe and solder for any required joints but proved unnecessary as  the zip tie was quite tight over the cabe for all the time i was experimenting

d

I made a mini change in the design :  I cut the cable in the middle, changed the poles in the middle of the wire while for the remain end i turned the cable so that the middle core could be in parallel and connected with a terminal block

 

and here is on how the mid points were connected:  It was much easier to jeep that quite safe and steady instead to use the solder. Its more than 15 years since i stopped using solder for making some basic electrical engineering . I also know a few technicians nearby my house who stopped soldering as most work  is just plug and play with mother boards!

 

this si the inversion part ..

Together with  joining the antenna parts I added a 'cloth hanger' . an idea seen in a antenna building This retains the shape of the cable.  Face-group Some short self bent wire tights the cable  soflty over the hanger

For more experimenting i used two different  lead cables to connect in the SDR or in the radio:
- a twin wire as used for electricity connections of 0.75 m2
-a 1.5  meter RG6 cable as in the photo 

The results were poor : Using the PL330 radio seen no  significant change in terms of noise caneling as far as i tested.

Putting the antenna over the railings (ie the metallic fence) raised the SNR to more than 10 db  Seen also a minimal level noise deletion as the antenna was turned

Testing with the spectrum analyzer as above shows many ghost carriers across the bands As you can see there are some relatively strong signals in the lower two bands there is also a huge noise level 

Instead of the band to be in the clear the SDR shown highly numerous unwanted carriers .someone called that close proximity but i think that most of them are unwanted spurs coming from the SDR or PC

step 2 

Something was  wrong for sure . Testing once again all connections i understood that the cables shields ends were  not connected each other . I removed  the plastic cover of shield ends by 1.5 cm and again used a new zip tie to keep them connected

the shielded part is shown in black

Results were quite better in terns of noise canceling. Signals were again the same with better reception above the railings but the spurious signals insisted  to exist 

step3

Finally days after , I have found a  toroid that is around 1,5 cm in diameter.This is the only available in the city. the balun designed was 1:1 using appliance twin cable . This was my fist time making a balun. Really a relatively easy job!

Again the problem with  the unwanted carriers existed  in  the SDR.  Tested not only with the RSP1a but also with the Aisrpy Discovery which made both SDR and program getting mad from the unwanted carriers

I was strikingly disappointed and dismantled the antenna and  immediately ordered the Youloop from RTLSDR blog via ebay ata cost of 40Eu . I was quite hurried to end these tests with this antenna but no sellers in Europe have been found in ebay or any other platform  for faster delivery

In the mean time :this is the  spectrum analysis of the 10 m antenna when is connected via the cable to BNC connector to the SDR (any SDR )

hmm it was a mistake: the  antenna wire was connected in the ground wire if he wire to BNC adaptor. the fault ws made by the person who soldered all the ends and connected the ground wire on the positive

 

By using connecting the ground cable in the BNC adaptor it adds many spurious . if using the ground to the the SDR case the curve is quite different and reduces the noise level! 

This is what happens when using a VHF whip , in the HF bands ...

update : the original antenna  has been received much earlier than i could expect that is in just two weeks . the report is the next in my blog and works very well

https://zachs-radiopage.blogspot.com/2022/03/short-review-for-youloop-antenna.html

update2: I m also expecting a clone model for test for testing their boxes that seems bigger and possible harder than their youloop counterparts at least by view This is 10 euros cheaper than the youloop

Powerline QRN

  POWERLINE QRN

 

A big problem for the DXer

Since last year a very big problem encountered from a strong noise coming from the nearby powerline electricity towers of 22 kV . It first happened about start of June last year and continued until the middle of October. It again started early this May and it still continues this time ( July 2003) with a short pause on June 25 and 26 when it reappeared after a strong lightning YThe level relatively vanished on mid september and is more rare.

For Last year ,as heard , the problem originates from the main transformer’s leakage

You can listen a sample of this noise here  as it was before July and how it now is heard

Depending of the band the noise level is a bit different. Here is a listing of the signal levels in tabular and graphical format

 

Freq MHz	Level	Att level
1.	7	2.5
2	0	/
3	1	-
4	3	-
5	4.5	-
6	7.5	-
7	9	2
8	9	3.5
9	8.5	1
10	7
11	2
12	4
13	4
14	3
15	1
16	0
17	3
18	4
19	2
20	2
21	5
22	2

 

It is necessary here to describe the problem with pictures

Before that , once again I must state that my antenna system consists of one horizontal 16m wire and one shortcut dipole with down connection of 16m and inactive dipoles of 16 m

 

Here is the picture near to our building  . You can see how close are the powerline 110 kV towers . Not more than 60 m far	Here is the nearby wiring network from electricity and other sources. Not shown the telephonic spources . Quite complicated , huh ?

 

In order to check if this really comes from the 22 kV electricity towers or from other local source I have travelled a bit to places around my point of ca 800 m far

Here are some results:

This is another view of the  dual power lines of 110 kV . 200mm below this  point the QRN seems to disappear.	And here at a point 1 km far from the house and again under the power lines . Here the noise level is quite high as in my house till the poit of the car  then the signal is cleared . What is funny , the powerline noise disappears from less than 100 m. I think that ist comes due to little wiring …

For the moment , I m overcoming the noise only using the MFJ noise canceller MFJ 1025 that works with two antennas by phasing out the QRN. However in most cases the tuning and phasing is quite tricky as for just a few kHZ off-tune the noise appears again

As in mid september  the problem seems  to be a little less. Some times   it seems big some times  less. According to a telcons professor    this may come from the insulators of the  high electricity towers . Moisture and dust  can effect on the quality of the insulators  producing sparks between them and the high voltage wires.

Last may (2003) I made a call to the national Electricity company DEI for this noise problem . The officer in charge insisted that I was the first claiming about it, and supposes it is a local transformer problem or due to possible overload from electrical appliances. (but still exists though we are in cold weather and rain for today ) It is expected powerline communications (also known as BPL) to start in late end this year by DEI s daughter company Tellas

---

UPDATE  A2006  

As of 2006 the noise  was audible only on trhe MW band 500 ca 2000 kHZ band  with S9  across it  The most peculiar of it , the nose was off for several hours in the morning , enabling me foe weekends  to listen to MW 

---

UPDATE  2 - ADSL supposed add-on 11/2006 but !!!  . 

The recent days (start of November 2006) I have made a request for ADSL line . though I have  not been informed by anyone  , i found the DX difference. There was just little QRN across  the bands.

However the same days  there was another noise added in our area from unknown source The shape levels are determined by a level of S9 on the 2-4 MHz lowering to about 6 mHz , being below S0 for the 6-10 mHz or S3 with 10 db pre-amplifier and then  somehow raised  from above the 16 mHz by a  nearly constant level of S2-3 on the 17-24 mHz . That happens on the 2x 16 m antenna 

The most peculiar is that the noise is starting from 1630-1730  LT !!! and continues at least till 0130

Using the 16 m horizontal antenna  there is a nearly constant level of S2-4 across most bands. on MW the noise is S10 in in contrast to S9 of V antenna , and a a harsh audio  above the 10 mHz . This   caused me an increase of tinnitus however... 

IN practice it can mean a relatively low rate of quite harsh  noise. In most cases it does not offer big amounts of nose , but in the lowers bands this noise is absolutely killing radio listening 

---

OTHER SOURCES OF QRN OBSERVED

Several other sources i found so far include: 

• satelitte TV receivers , and  most particularly hard disks on sat antennas. I own a Dreambox receiver which in very short time i built-in a hard disk.With the hard disk a rasor sounded  noise is heard with up to S3 on the 2x16 m antenna 
• Fluorescent lamps: They add a huge amount of noises , usually S 5-7 . This is the reason , though my older work,  that i complete removed them from  house. 
• TV set :  again i have observed very low levels. Most susceptible band comes the 10-11MHz band  

And one supposedly  adding a lot of noise  but was in the reverse: 

• Computer: believe itor not  my 3 GHZ computer , with TFT 17",  scanner , optical mouse , laser printer  etc , did not produce any noises 
• The 17' tft monitor is above the radio and produe very low levels of noise  that can annoy only if i have to listen to  very poor signals (below S2 with preamp!!!)  in the MW and 10-11 MHZ bands
• Printer  adds  some noise only when printing occurs 
• The horizontal antenna is more susceptible to any noises  generated from any type of sources . BY shutting off computer a white noise generated  in the 16- 20 MHZ band  is stopped , leveled S2 only
  

If someone has any idea how to overcome this noise , without using the MFJ canceller, please let me know at zliangas! @! YAHOO com 

 this pafge i also on anotehr main page