BA Dual conversion receivers

[XJet]

A friend purchased several BA Dual Conversion receivers but they only give him 7 paces of range with the transmitter antenna retracted.

All other receivers (not BA) give at least 40 paces.

There's no way these can be used like a regular dual-conversion receiver because they just don't have the range needed for anything other than an indoor model -- so they're useless to him.

The sensitivity is listed as < 2uV, the same as the Corona units which provide 50-paces of range without any problems and the webpage claims "Effective Receiving ranging: >800M". There's no way these units provide even 1/5th that range.

Also, just looking at the design, there's *no way* I'd trust one of these receivers to anything other than a very small, lightweight model. They have very limited IF filtering (ie: poor adjacent channel rejection) and a very broad front-end plus an extremely poor dynamic range (ie: overloaded/swamping at 1 pace, out of range at 7 paces).

In short, I'd say that these are the *worst* dual conversion receivers I've ever seen and aren't even suitable as a paper-weight (they're too light for that :-)

What do you suggest he does?

Can he return them for a credit against some 40MHz Corona receivers?

[CSO#1 @UHobbies]

I suggest your friend send us an email and we can discuss it with him/her.

Your observations are in stark contrast to our findings and user reports.
We would be very interested to recieve these Rx back so we can test them.

Please have your friend contact us.

Rgds
Karen.

[osiris4isis]

A friend purchased several BA Dual Conversion receivers but they only give him 7 paces of range with the transmitter antenna retracted.
\

Using transmitter with antenna retracted is not a good idea. What is the
range when the antenna is fully extended?

[Probedude]

Using transmitter with antenna retracted is not a good idea. What is the
range when the antenna is fully extended?

It's only done to test the range of the receiver.

[XJet]

I should add that these are 40MHz versions -- has anyone else tried these?

As I already mentioned, I could see (just by a quick visual examination of the design) that they are *not* what I'd call full-range receivers and I was not surprised when they offered such poor range and exhibited a tendency to overload at closer ranges.

The Corona receivers (similar price, similar "on paper specifications") are of a vastly superior design with a propper tuned front end and IF filtering -- like a good DC receiver *should* have.

The antenna-up range was already getting flakey at just 70 paces or so. These receivers were tested with the supplied crystals and the transmitter in question range-tests fine with a Futaba PCM and FM receiver.

All the receivers tested exhibit the same poor range and swamping.

I'd have to say (based on this) these are definitely an "avoid, avoid avoid" product and I hope that UH replaces them with receivers that *do* live up to their written specs so as to sort out this customers' concerns.

[CSO#1 @UHobbies]

Point taken XJet, and your comments alone have caused us to hold off on our next invoice and test them further.
We have not experience the poor results that you mention, we have had much better results, though our conditions are slightly controlled and the antenna is always fully extended.

What crystals did you use?
What transmitter did you use?
Im seeing a hint of technical ability here from you, though I dont see any controlled data or information.
Can you give me some more information on your range tests. Equipment used?

Thanks
Jason.

[XJet]

The crystals used were the ones that came with the receiver.

I'm an electronics (digital and RF) technician with over 30 years experience in the fields of industrial and commercial radio control, telemetry, process control and communications.

The tests were simply a range-check at the local flying field but after the poor result I took a quick look at the design of the receiver and wasn't impressed with what I saw.

I can provide you with a more technical and elaborate analysis if you like.

[CSO#1 @UHobbies]

The crystals used were the ones that came with the receiver.

I'm an electronics (digital and RF) technician with over 30 years experience in the fields of industrial and commercial radio control, telemetry, process control and communications.

The tests were simply a range-check at the local flying field but after the poor result I took a quick look at the design of the receiver and wasn't impressed with what I saw.

I can provide you with a more technical and elaborate analysis if you like.

You used the crystal included in the reciever package?
What model receiver did you have? BA now have the R8DM and the R8D, I am aware that the R8D was... not so fantastic. Though we never had the pleasure of stocking that item.

We have only ever had rave reviews from the Corona Rx's, and from personal experience they are great.
Our tests show the Blue Arrow products are what they say they are and give more distance than what is said in this discussion. So Im very interested to know more.
Perhaps there is a brand of radio, crystal or something that is causing these issues.

Rgds
Jason

[MartinL]

I just did a range test on my new BA R8DM on 36 MHZ Oz freq..
With the Rx sitting on the ground I can only manage 5 paces b4 it lost control..
I thought maybe it does not like siting on the ground, some of the guys at my club had this problem, so I placed it on a stood u know what it?? passed with flying colors..I walk atleast 60 yards and it was still solid. Now the flying test..my field is a glitch galore field..with cell phone towers nearby/stadium next door with all kind of electrical equip..we will see.

I never trust BA rx.. I bought my 1st 4 channel about 1.5 years back and never use it in a plane...cant pass a 5 paces test either way...even their motors do not have proper magnets.

I bought the BA by mistake..I thought I was ordering a Corona :(

[idealera]

Hello XJet and MartinL

My friend from BA asked me to reply your questions on his behalf

As for your receiving range problem, he said during their extensive laboratory and field tests these dual conversion receivers can get solid signal over 800m without any problem.

Please post the TX you used and your detailed test methods and results.

Regarding your doubt about "poor" filtering circuit on PCB BA adopts industrial first software filtering solution. This is achieved by the power of on-board microprocessor and software. It’s NOT a hardware solution. Minimal adjacent frequency interference is guaranteed.

Here is their test methodology

They used three adjacent frequency crystals
40.765 CH57 40.775 CH58
40.770 CH77

Radio is less powerful Futaba 4VF on 40.770 CH77

Walked one pace away from receiver and has the radio antenna just over rx

The receiver will not make any response with 40.765 CH57 or 40.775 CH58 crystals installed

Please tell me your test method for frequency interference

I will forward all of your info to BA. :cool:

[MartinL]

I m not technically minded but lots of experience with Rx. 90% of my Rx (20 +units) are Schulze 835 and 535(in the US is the Berg) I use the Futaba 9CAP on 36mhz, my freq is 36530. On my normal Rxs on ground range check I can walk 50 paces without any failing, trottle on or off. The current BA I am testing works ok "off" the ground and ok in the air if there are no other electrical noise. I flew with the BA yesterday morning, it flew for 8 mins incident free but on my final approach adjacent to the area which is prone to glitches it nose dived into the ground breaking off the frontal of my plane. I get glitches quite often but normally it is only a 1 sec kick, but not lock down like this crash. I will not use it in my plane again but I will use it in my boat. The previous experience with the 4 channel was even worst..never pass any range test.
The filtering I guess is like other so so Rx, but u need to look at how to not lockup for 3+ seconds..

[XJet]

Hello XJet and MartinL

My friend from BA asked me to reply your questions on his behalf

As for your receiving range problem, he said during their extensive laboratory and field tests these dual conversion receivers can get solid signal over 800m without any problem.

Please post the TX you used and your detailed test methods and results.

The transmitter was a Futaba 8U with a 40.750 fixed-frequency module that works perfectly well with regular Futaba PPM and PCM receivers. The same transmitter also works perfectly with 72MHz modules (fixed and synth) and the Corona receivers.

The output field-strength of the transmitter is identical to a Futaba 9C, but this is to be expected since they use the same RF circuitry and antenna. I have no reason to believe there is a problem with this transmitter.

Regarding your doubt about "poor" filtering circuit on PCB BA adopts industrial first software filtering solution. This is achieved by the power of on-board microprocessor and software. It’s NOT a hardware solution. Minimal adjacent frequency interference is guaranteed.
This is very bad news.

Software filtering is nowhere near as effective, safe or reliable as proper RF/IF filtering.

By not having proper RF/IF filtering, the receiver becomes extremely susceptible to cross-mod/intermod and image problems that the software can only try to mitigate.

This means that any such receiver is far more likely to suffer from out-of-band interference (ie: strong signals on frequencies that may be some MHz away from the operating frequency).

It also means that the receiver could be upset by various combinations of other in-band frequencies -- this is called second and third-order intermodulation.

Software-based digital signal processing (DSP) is a great addition to a good solid RF design but certainly *not* a replacement for it. A good example of this is the Berg receivers... they use good RF design (a well-tuned front end), and excellent IF filtering (multiple multi-pole ceramic filters) which means that the DSP only has to cope with interference that is on-frequency. The intermod/cross-mod performance of the Berg is very good for a single-conversion receiver and I suspect, despite its "dual conversion", the BA will be significantly inferior when I actually test these aspects of its operation.

Your comments confirm my observations that this receiver lacks proper RF/IF filtering and tries to compensate by using software. This is a very cheap way to build a receiver but the results are seldom good.

Other manufacturers such as Berg and Corona have a solid RF/IF design which then uses digital processing as another layer of protection to augment, not replace that good analog design.


Here is their test methodology

They used three adjacent frequency crystals
40.765 CH57 40.775 CH58
40.770 CH77

Radio is less powerful Futaba 4VF on 40.770 CH77

Walked one pace away from receiver and has the radio antenna just over rx

The receiver will not make any response with 40.765 CH57 or 40.775 CH58 crystals installed

Please tell me your test method for frequency interference

I will forward all of your info to BA. :cool:

This test method only tests adjacent channel rejection -- it does not demonstrate the effect of multiple strong signals being received simultaneously by the receiver.

A better test is to have the receiver and a transmitter on the same channel, separated by a reasonable distance (say 20 paces with the transmitter antenna retracted). Then turn on another transmitter (on an adjacent channel) with its antenna fully extended and just 5 paces away.

This will show up the receiver's ability (or inability) to handle the kind of environment that can often be encountered in real-life use situations -- such as when you fly past the flight line while someone else is on an adjacent channel. At some point their signal will be stronger than yours but your receiver will be forced to handle *both*.

You should also test the receiver's ability to handle a very strong signal from the transmitter -- ie: the transmitter and receiver antennas within two or three feet of each other with the transmitter antenna fully extended. This should not affect operation or cause any loss of control, latency etc.

Tests should also be made to see whether a strong out-of-band signal (such as might be received from a radio-telephone, CB set, amateur radio, etc) causes the receiver to be desensitized (ie: reduces the range). I suspect the BA receivers are far more susceptible to this than other designs due to their lack of proper front-end filtering.

I can perform a full suite of tests on this receiver if someone wants, but it'll take a while before I have a hole in my schedule to do so.

If BA are *designing* these receivers properly they should have the technical specifications relating to such things and make them available to be confirmed by an independent third party anyway.

At this stage, I stick by my statement that I would not fly a model with one of these receivers, especially if it was at a busy flying field or in an area where there was likely to be any other source of strong radio-frequency signals (on any frequency).

The BA designers are welcome to contact me directly it they want.

[Probedude]

Regarding your doubt about "poor" filtering circuit on PCB BA adopts industrial first software filtering solution. This is achieved by the power of on-board microprocessor and software. It’s NOT a hardware solution. Minimal adjacent frequency interference is guaranteed.


As the other poster mentioned, having the software 'filter' is a horrible way to do it. If the RF front end is sending gibberish to the MCU the software is not going to be able to pick out the desired signal, only ignore it.

Dave

[Maximilianus]

This sounds like bad new about these BA dual conversion receivers. :eek:

@ United Hobbies
Any chance of swapping it for a Corona receiver??? :rolleyes:

Max

[CSO#1 @UHobbies]

Do you know who 'idealera' is?
It's the China sales rep for BA!
So dont think your comments havnt gone unheard.

[idealera]

CSO#1 @UHobbies :confused:

[CSO#1 @UHobbies]

C'mon Luke. Dont be shy now.
You should have used a different username. At least not used the same name as your sales email at gmail.com

It's good to see the factory sales rep taking action and listening to customers.
Lets all look forward to a new BA Rx, Im sure the comments of xjet wont fall on deaf ears.

Rgds
Jason.

[gmo78]

I have a BA rx, 4 chanel, I think than the maximum range is not more than 40-50 meters!
But on Corona 620 I cannot tell nothing bad, I have 2 620 with hitec and webra dual conversion quartz. Before I had big interference problems with electron6 rx, so I tried to replace with corona 620 and finally I was able to made 2 flights without any interference or lost of signal.

[Chris F]

Any news on these Rx's? I have one and I don't want to use it if it's no good. Also I don't want to hunt down a micro DC crystal for it if it won't do the job.

[XJet]

Chris, my advice would be to toss your BA DC receiver (or return it) and get a Corona DC.

I've been testing the Corona SC and DC receivers on 72 and 40MHz and they are truly excellent. The SC is every bit as good as a Berg and the DC ones are way ahead of most other offerings from the likes of Hitec, JR and Futaba in terms of value and performance.

The other benefit of the Corona is that the DC receiver takes regular-sized crystals so you can use 36MHz ones from Hitec or Futaba that can be sourced from your local dealer.

[Chris F]

Hi XJet,

I have already bought two of the Corona Rx's from UH. I'll see if I can send back this Blue Arrow and replace for another Corona.

[Styx]

Does the crystals UH have fit the Corona receivers as well?

[XJet]

The BA mini crystals fit the single-conversion Corona but not the dual conversion.

[dave05]

CSO#1 @UHobbies i have the BA R8DM36 i have not used it but after reading this im not sure i want to i see they arent on the UH site any more can i return this for a credit if so where do i send it etc

many thanxs Dave