Chinese 500mW should only use QN8007 chip

[FMEnjoyer]

Chinese transmitter manufacturers should start to make the 500mW USB 3.0 C-Type powered FM transmitters using the QN8007 and NOT the QN8027 - very low quality.

We all now know the QN8007 part chip is far superior in every way. Lower spurious and lower harmonics and better stereo sound quality.

I believe these would sell very well as no one on the planet wants to knowingly interfere with any other radio services.

There are 2 designs one in a small box and the Black PCB sandwich type both with SMA connector. These small devices seem to have a filtering arrangement. Of course that should be kept.

Clearly advertise it is made with QN8007

这是针对中国发射器制造商的

中国发射机制造商应该开始使用 QN8007 而不是 QN8027 制造 500mW USB 3.0 C 型有源发射机——质量非常低。 我们现在都知道 QN8007 零件芯片在各个方面都远胜一筹。更低的杂散和低谐波以及更好的立体声音质。 我相信这些会卖得很好，因为地球上没有人愿意故意干扰任何其他无线电服务。 有 2 种设计，一种在小盒子中，另一种是黑色 PCB 夹层类型，均带有 SMA 连接器。 这些小型设备似乎具有过滤安排。当然应该保留。 明确宣传它是用 QN8007 制造的

These types:

https://dwmzone.com/en/raspberry-pi/105 ... splay.html

https://www.aliexpress.com/item/1005007 ... ry_from%3A

Quintic QN8007 datasheet

https://file2.dzsc.com/icpdf/18/07/11/6 ... 915924.pdf

[rigmo]

good to know
"This is for Chinese transmitter manufacturers

Chinese transmitter manufacturers should start making 500mW USB 3.0 Type C active transmitters using the QN8007 instead of the QN8027 - very low quality. We all know by now that the QN8007 parts chip is far superior in every way. Lower spurious and low harmonics and better stereo sound quality. I'm sure these will sell well as no one on the planet wants to intentionally interfere with any other radio service. There are 2 designs, one in a small box and the other a black PCB sandwich type, both with SMA connectors. These small devices appear to have filtering arrangements. This should certainly be kept. Clearly advertised as being made with the QN8007
"

[FMEnjoyer]

If these 500mW devices are to be sold at least make them with the best available chip product the Quintic QN8007. They are going to be sold whatever happens so at least they can be as clean from spurious as they can be and the QN8007 appears to provide much lowest spurious and harmonics.

The QN 8027 is terrible. You can see on this video here at 08:45 a list of chips and specs :



One of these could go 3 miles up high so it would be much better if they were using the much cleaner QN8007.

[radionortheast]

its quite hard to see what chips are inside they do scrub out the numbers I suppose, I had two black ones half a watt, one with the display was bad quality also wouldn’t put out half a watt, the other was better no display on it, did put out half a watt!, later found out it was putting out smaller duplicate signal half way up the band, the audio quality was not so bad on it, the duplicate made it no good, ok for round the house with a short antenna.
The retekess ft11 is the best i’ve found putting out less mush, it dosen’t have proper sma antenna socket thought, also only puts out half a watt on a low frequency, think it was designed to work with a short rubber duck antenna so its not very good at a high frequency, good luck hearing that far away on such congested frequencies.
The other issue with these things is the sound, the stereo often has too many high frequencies, none have an mpx input, you have experiment with different caps between left and right to ground to get a softer sound, you don't know what pre emp their using. The bh1417f is the only one were you can connect your own own stereo encoder, can also be used as stand alone encoder , the transmitter is only hard wired to work on 8 frequencies has problems picking up hum, 1Mhz round the signal is a bit messy.

[FMEnjoyer]

They use the very worst chip the QN8027, seen one.



Production using QN8027 should be stopped immediately and they should redesign around the Quintic QN8007 which is by far superior. Even if price increases by a few dollars. In 2024 these things should be using the best chip -QN8007- not the worst.

At 500mW they become much cleaner for everyone who cares about not interfering and that contrary to authority belief that is everyone unless they do not research. Less interference means less likely to get trouble off anyone.

There are 1,000 x more people who would enjoy radio fun who don't want to run a 200 Watt station.

You can do a lot with 500mW.

STOP using QN8027 in 500mW TX and only use Quintic QN8007.

They are a $1 part !

https://www.win-source.net/products/det ... 8007b.html

[biggiedan]

Out of curiosity does anyone know what the NS741 IC is like?

[oazz]

The bh1417f is the only one were you can connect your own own stereo encoder, can also be used as stand alone encoder

The bh1415f too can connect the stereocoder with the Stereo Tool program.

[rigmo]

[rigmo]

https://www.banggood.com/Bluetooth-Enab ... 14431.html
any data of this cicruit inside'

[EFR]

I dont understand why you mess with these crapboxes?

[oazz]

I dont understand why you mess with these crapboxes?

If you will buy such transmitter you will not speak any more that it is a crappy box. I have a such.

https://www.ebay.com/itm/375815723475?_ ... R5aN7sr6ZA

[EFR]

Hmm, I just might use my xmas bonus to buy one and measure it.

[FMEnjoyer]

I dont understand why you mess with these crapboxes?

I will let you in on why many may find them attractive. Tiny size, extremely light weight, stereo, 500mW RF output, incredibly low power consumption, easy to drive audio wise, easy connectors, capable of 2-3miles in the clear, not too fussy about SWR due to low power output, extremely easy and convenient to power for 20 hours plus using a lithium power pack, easy to procure, they cost £20.00

That a lot of positive, the downside is the terrible chip they use which is currently a QN8027-BAD they should use QN8007-GOOD

That's why and as they are sold no matter what, I think the best for all is they at least have the Quintec QN8007 which is noted for significantly less spurious emissions which is of course good for all.

I assume that these 6 coils are a form of filtering ? Which should be kept even if they used a QN8007

[FMEnjoyer]

I dont understand why you mess with these crapboxes?

If you will buy such transmitter you will not speak any more that it is a crappy box. I have a such.

https://www.ebay.com/itm/375815723475?_ ... R5aN7sr6ZA

Going slightly off topic as I was focused on the 500mW mini Tx's. It is very difficult to be sure about specs. I would take the specs with a pinch of salt. Even the chip it is based on has worse specs than they state. Second harmonic -65dBc and spurious -56dB whereas the chip says -45dBc. Unless there is a lot of filtering in the P.A.

oazz as you own one, can you tell if there is a filter network, coils..... under the heatsink where the RF P.A transistor would be in your photo below, as there is nothing visible in the photo below that looks like filters for harmonic and spurious. It might be under the big heatsink ?



If the coils are under the heatsink that would be somewhat reassuring but if there are none then it would suggest no kind of interference suppression which would be really strange as even the 500mW attempt some filtering. It would be interesting if you could let us know. if so the Chinese rigs are actually getting quite a bit better.

[rigmo]

If you will buy such transmitter you will not speak any more that it is a crappy box. I have a such.

https://www.ebay.com/itm/375815723475

No rds price is litle to high...

[radionortheast]

https://www.banggood.com/Bluetooth-Enab ... 14431.html
any data of this cicruit inside'

unfornately I had one of those, its no good simliar to an 8027, lots spurs, low rf output too

[radionortheast]

I assume that these 6 coils are a form of filtering ? Which should be kept even if they used a QN8007

The coils are there to filter the output to match it to the antenna, pass signals in the 87.5 - 108 range filter them out above or below it, were more concerned about above the fm band, theres the harmonics too which it will reduce, a badly matched output can create spurs.
An output filter like in the picture you can change the value of the capacitors, use ic sockets plug in different values or use variable trimmer caps, to get a better match, the caps go between ground and the coils (the signal)

[FMEnjoyer]

I assume that these 6 coils are a form of filtering ? Which should be kept even if they used a QN8007

The coils are there to filter the output to match it to the antenna, pass signals in the 87.5 - 108 range filter them out above or below it, were more concerned about above the fm band, theres the harmonics too which it will reduce, a badly matched output can create spurs.
An output filter like in the picture you can change the value of the capacitors, use ic sockets plug in different values or use variable trimmer caps, to get a better match, the caps go between ground and the coils (the signal)

Thx radionortheast, at least they bothered with some form of harmonic filtering, it can be presume this is insufficient then.

May I ask what you measured in mW from the QN8027 in terms of RF outlet if less than 500mW, thx.

I suspect if they started making them with the QN8007 they would be much cleaner and why I am suggesting it.
Flea power rigs are potentially a lot of fun, but everyone will want clean ones, and if we do not ask we will not get.

These days I suspect few hobbyists want to run on a block unless they are in a massive city. However more may want a bit of fun in the neighbourhood or a mess around for an hour but would want that to be clean. An entire station could be gaffer taped to the end of a fiberglass flag pole complete with cheap audio source mp3, 500mW light weight little rig with its telescopic antenna, power source USB C lithium mobile pack. Easily crocodile clip a set of 3 x 75cms long radials onto the negative side of the SMA screw connector. Or the equivalent second half of a dipole and you have a station-on-a-stick. Adding the clip on radials spread out a bit using thin solid core wire would make a pretty decent match, much better than the telescopic alone.

But you would NOT want to do that with the QN8027 chip inside. QN8007 would stop the interfering potential as they are noted as cleaner chips.

If they can run on a single + side telescopic antenna without burning out that should better the match and range.

[radionortheast]

Thx radionortheast, at least they bothered with some form of harmonic filtering, it can be presume this is insufficient then.

May I ask what you measured in mW from the QN8027 in terms of RF outlet if less than 500mW, thx.

Lucky I still have it, I have looked at it again, appears there are different power levels it was set to 4, it was +13.4dbm, 0.0219 so 21mw, that explains the low power level from it, you have to long press the right hand button, with it set to 10, the power is quite decent.
The spurs go away when it is set to the maximum power level, with a dipole, may differ with a telescopic rod attached to it. There is a duplicate carrier, with it set to 88.3, it is on 100.3, another below around 76, if you change frequencies they will also change.
The dupilcate carrier is strong enough to get round the house, could well come across another station, it is likely afew mw. The one I have without the display does do the samething, the duplicate carrier is suppressed (probably barely a milliwat) so less likely to come across anything and they are not varying the power on it, you will pleased to know the filter is working, both are filtering out the harmonics. Does seem with it they are trying to vary the output power on the one with the display which is a problem.

[FMEnjoyer]

thx for the info northeast