Hell NO!! The 150w Chinese TX is now here.

[teckniqs]

http://www.ebay.co.uk/itm/172348606554

It was only a matter of time and now it's here!! ...If 5w of pure nasties isn't bad enough for you, now you can have 150 and take out half of the world!

[Analyser]

Lord, help us all!

In fact you can tell how much noise there is around the carrier just by the slightly raised noise-floor. Even though the resolution bandwidth of their Rigol SA is not set to show the spurs properly it's obviously so bad that the noise floow lifts up.

[Analyser]

Struggling to find the "planes will fall button".

...wonder what the USB socket is for?

[teckniqs]

Haha that icon/smiley is on the next page.

I think it's probably just a 5v output to power something like an mp3 player, what this type transmitter should only be used with!

[pirateaddict]

Shocking... Seems to me all the Chinese make is shite! Everything that comes out of that place is shit.. They should be banned from making owt!

[Analyser]

The concept itself is quite nice, I mean if you take the little LCD with power/ swr/ temp readout and all the other stuff that they've taken the time to implement it would be great. Even the PA looks ok RF-wise. Just a shame they can't be arsed to use anything decent for the VCO, lets the whole thing down so it's totally pointless.
Shame.



(still can't find the planes 'ting, Tek)

[teckniqs]

By the time you've boxed it up with PSU etc etc it's still gonna cost the same as a decent 150w from a builder!

[Ahh looks like it may have either disappeared or they never even had it on this forum...lol]

[bristolpirates]

Could you remove the chip and feed it with the signal from a decent exciter?

I suppose from a price point of view, that wouldn't be worth it, and you'd loose the extras like the SWR and temp readout.

[Albert H]

I've seen that sort of thing done - the SWR output from the PA is a voltage proportional to the reflected (and forward) power, so you can detect and indicate this however you want. The stereo "broadcaster" chips really shouldn't be amplified - they're truly nasty!

The same website has 150W and 300W PAs. I've seen both of these in action, and they actually work as advertised. There's a kit version of the 150W board available (if you shop around) for about £25. You can get a cheap 48V PSU for about the same money. If you can build a good exciter.... You're looking at a 150W rig for around £100

[MiXiN]

http://www.ebay.co.uk/itm/172348606554

It was only a matter of time and now it's here!! ...If 5w of pure nasties isn't bad enough for you, now you can have 150 and take out half of the world!

This is a nightmare come true, and is well & truly going to put another nail in the Coffin for those of us who try our best with clean gear.

OFCOM are gonna have a field day with the surge of these hitting the UK.

[teckniqs]

Could you remove the chip and feed it with the signal from a decent exciter?

I suppose from a price point of view, that wouldn't be worth it, and you'd loose the extras like the SWR and temp readout.

You could probably feed the RF from a decent exciter into the power amplifier stage, I don't see why not. You'd still get the SWR and power read out that way but it would end up costing an arm and a leg doing all that!

...You can't polish a turd.

[DJ Mikey]

Just wait until these start hitting ebay and sites like that then silly bollox and hes mates from London who has no idea about radio buys 1 and wacks 1 on, this is very bad news, the fact any cunt can get their hands on a 5w was bad enough, is there no way to stop the sale of things like this knowing how dangerous and bad it can be ?

[UKNECKS]

Hi guys,

I don't understand something. Pirat want cheap thing, no you have cheap transmitter and your are not happy ? It has very noisy VCO and lot of spures and intermods sevrals MHz aways....(that can ruin the aviation communication)... Event the amp could be unstable by self interstage oscilating in certain conditions as common rf design... But please don't complain, it cheap so that all you want. You should be happy !

Sometime I feel out of phase...

[teckniqs]

Hi guys,

I don't understand something. Pirat want cheap thing, no you have cheap transmitter and your are not happy ? It has very noisy VCO and lot of spures and intermods sevrals MHz aways....(that can ruin the aviation communication)... Event the amp could be unstable by self interstage oscilating in certain conditions as common rf design... But please don't complain, it cheap so that all you want. You should be happy !

Sometime I feel out of phase...

You should! ...I wouldn't expect you to understand.

[Banus_radio]

Hi guys,

I don't understand something. Pirat want cheap thing, no you have cheap transmitter and your are not happy ? It has very noisy VCO and lot of spures and intermods sevrals MHz aways....(that can ruin the aviation communication)... Event the amp could be unstable by self interstage oscilating in certain conditions as common rf design... But please don't complain, it cheap so that all you want. You should be happy !

Sometime I feel out of phase...

wow, this guy never learns!

Florence your stuff is not cheap enough for the average pirate user to leave it on a rooftop somewhere only to be stolen.

This chinese stuff is cheap but not worth running, its so noisey. How can you not understand that?

An average London Stlye transmitter costs around £270 - £330 for a decent clean 200watter including receiver, all boxed up and ready to use including vswr protection... thats cheap and value for money!!

[shuffy]

I haven't seen a complete Chinese transmitter in the flesh but some of the boards on Ebay (including this 150W one) appear to have half decent PAs. I can't speak for the quality of the components and PCBs used though, I expect they're poor. One TX I saw a picture of (I think it was one of those 7W ones in a silver box) had a terrible overall layout including the PA. If it was clean (VCO notwithstanding) it would only be by accident.

The 100W Chinese PA with the MRF186 works very well and I know a few builders who are using these boards now. With the filter fixed and a decent driver, you can produce a rig within spec and accepted price point. (Can't comment on the 170W version at the moment because so far I've managed to dispatch one FET due to carelessness/ignorance!)

Floris that was a cheap shot (unlike your gear). I have no doubt that your designs are top notch but you're aiming them, at least in part, at pirates. Everyone wants to minimise costs, but within that, there are 2 main groupings. Those who appreciate the need to balance out the cost against quality and those who don't give a shit. It's the latter grouping who are going to buy these BA1404 rigs and hopefully OFCOM will get their fingers out and teach them a lesson.

You're not going to sell many units to pirates - so why try to pitch to pirates? Why not box up and/or build for small commercials internationally? You'll have to sort your marketing out though.

[teckniqs]

And yes Floris - Pirate radio means that a transmitter is REQUIRED TO BE IN A BOX....

I'm not even sure what market your equipment is intended for?? I mean it's not like anyone would be leaving that up on a roof or be jacking that thing in without mangling it to death.

Your gear is merely for the domestic/bedroom broadcaster unless it's enclosed in a box but hang on ....wait a minute .....what bedroom broadcaster is gonna have 650 blood clarts banging out their of their nan's loft????

You may have sold loads of these unit's or you probably might not and if you haven't this would be one of the main reasons why!

...I'd say your kind of gear could be more attractive to the U.S market who tend to spend more money on their TX gear and use more power than we usually do in London, but your huge naked PCB board simply bolted on to a heat sink with those trailing wires onto power supplies etc so is no good for 99% of serious FM stations.

Before I go I just wanna say I've always thought that your stuff looks pretty decent I ain't gonna lie...
But just a big open circuit board attached to a giant heatsink doesn't look like a professional transmission product and I think you could do a lot more if you looked into boxing up your stuff!
If the RF output is as clean and it works as well as you claim then it could be some pretty nifty kit for some people with all those added features like RDS, Stereo, limiters, compressors etc built in but still it's not so good for the UK pirate market even if it was in a nice long skinny (jackable) box.

[Shedbuilt]

Lord, help us all!

In fact you can tell how much noise there is around the carrier just by the slightly raised noise-floor. Even though the resolution bandwidth of their Rigol SA is not set to show the spurs properly it's obviously so bad that the noise floow lifts up.

I don't know that SA at all, but if I'm reading the photos correctly, it looks as if it is configured to give a reading in Watts, and it looks as if each division is ~6dB, which would mean that most of the noise floor - as it's captured in the photos, is only 30 odd dB beneath the carrier (mostly in the band between 13mW and 54mW). Nearer the carrier, it's getting into the low 30s. If we zoomed in a bit........

[Albert H]

Shedbuilt - you're right. It's not a great trace! I've just checked a 40 Watt box I have here against one of those iTrip efforts....

On my HP analyser, the unmodulated carrier from the 40 Watt rig gives a single, narrow spike. When adjusted to measure carrier to noise floor, there's a slight increase around the carrier - from -97dBc to -95dBc (I had to check several times to see any noise increase) for about 100kHz around the carrier. The second and third harmonics are similarly thin spikes and just -77dBc and -86dBc. The couple of milliwatts of harmonics and noise are unlikely to make it up the coax!

I then tried the BA1417-based board. The carrier is broader because it's always modulated with the stereo pilot. The noise floor and spurs around the carrier - mostly multiples of 38kHz and 100kHz - are between -10dBc and -17dBc. There was also a general increase in noise floor around the carrier bringing it up to just -27dBc....

The (obvious) conclusion is that the "audio-sender" chips are OK for what they're meant to do - send stereo audio from your iPod to a car radio - but amplifying them is just stupid. Just for my own amusement, I decided to build an "equivalent" of one of these audio-senders. I used six CMOS chips, a crystal and three transistors. I got a clean, PLL-stabilised stereo carrier, with no products worse than -78dBc and an output power of 80mW (much more than an iTrip). Cost of parts - about £2.50. The cost in China would be about 80p. The board would have to be bigger than with the single IC (6p in China), but the results would be much better. If the Shenzhen chaps decided to ditch the Rohm chips and build proper mini-transmitters, the VHF band everywhere would be much cleaner!

[OgreVorbis]

I found out the chip is QN8036. The chinaman admitted it to me and I zoomed on the pic and it looks like the right chip. The datasheet (extremely hard to find the full version) states in the specs a -45dBc noise floor at worst point. I believe this spec because I tested a similar chip RDA5820 and the datasheet looked like somewhat of a clone.

Anyway, looking at the real data, at 150W, this means the spurs are about 5mW of power. I might hook up a rig and set it that low to see how far it goes. If someone else wants to do the test, I'd be interested.

Unless I am missing something, it can't possibly go very far.

I don't know how much power is wasted in those spurs though because they are a few mhz wide (there's probably a formula).