Who makes these?

[EFR]

Tested unit was this:
https://www.ebay.com/itm/375727417729

Sorry for spamming, but my brains are diffrent, not enough caffeine yet.

[shuffy]

Thanks EFR for spending the time and money!

I think this one says everything.

So that's the new super duper "planes will not fall" version

[FMEnjoyer]

It's funny that people seem to think that "block-based" broadcasters are a thing of the past. One regular rig-builder I know is getting more work than ever - perhaps many of the "regulars" are retiring from the game.

Constructing reasonably powerful rigs is quite easy these days (assuming you've got all the relevant test gear). A 200 Watt PA can be fully driven with less than a Watt these days, as the gain of some of the FETs available is astonishing. I remember the "bad old days" of RF power transistors with 6 - 7 dB of gain. A 40 Watt output PA could need as much as 7 Watts of drive back then. These days, we've done away with the driver stage, as a flea-power exciter will fully drive those FETs!

PLLs used to be difficult. Getting prescaler ICs that would go fast enough could be expensive, as they were quite rare. The Plessey ECL chips (SP8629 was a favourite) were a game changer. The prescaler would divide by 100, bringing the Band II signal down to CMOS data rates. I used to use the Plessey SL560 (a three-transistor amplifier in an 8-pin DIL package, with the base and emitter of the first transistor on two of the pins, allowing configuration as a Colpitts oscillator) for the Band II oscillator and buffer, driving into a 2N4427 giving about 750mW. The PLL would generate a reference at 1/100th of the output frequency, and this would be compared with the prescaler output to give a steering voltage for the Band II oscillator. For the first time we had rigs that didn't drift at all!

It is easy if you have £4K of test gear and are an RF engineer. In your case what 40 years ?

No one has time in 2025. And I have an attention span greater than most, but the days of farting around with PCB's are over. There are just better things to spend time doing. making things simple for end user is a real thing.

I am not stupid we know that the Chinese parts QC will be diabolic and what gets sent out may not quite be what is shown in a picture or video, with all the filtering and shielding you see in any given tear down video. But I have seen zero spectrum analysis on a block pirates FM rig so it is very rich to condemn the Chinese analysis of the better chips.

I have somewhere a MAXPRO2015+ in mono.... I had a laptop that drove it, phones, mp3s quick and dirty audio source...no chance very under modulated.

People fall into 2 camps highly technical, a bit technical and want to learn or can make an antenna and use an VSWR / power meter.

I don't know but what I do know is there are no where near the pirates on in the SE as there was 15 years ago. I can hear 1 and the reception is terrible, I have to use a toaster as a ground plane under the radio in my kitchen and 0.8m long whip on my tecsun to hear them, no other radio has a chance.

In fact if anyone wants to bring signal in a bit better put a large metal object under your portable radio if indoors that does help, can make something on the edge listenable, you get 3dB extra or so.

All dangerous anyway these days and largely pointless as people listen to FM less and less.

I think the import is a max of £135.00 before you get other fees.

[FMEnjoyer]

editing it

[FMEnjoyer]

I think this one says everything.

https://ibb.co/7SdCyqq

About -46db down from carrier, just 5 db out of spec from the QN8007 saying -50dB, that could be a lot worse.

Not so bad after all.

[EFR]

Still strong modulated harmonic at 50Mhz, does that chip run on 50Mhz with doupler?

[EFR]

I think this one says everything.

https://ibb.co/7SdCyqq

About -46db down from carrier, just 5 db out of spec from the QN8007 saying -50dB, that could be a lot worse.

Not so bad after all.

And noise is about 10Mhz on airband side...
https://ibb.co/j8fBZbh

[FMEnjoyer]

I think this one says everything.

https://ibb.co/7SdCyqq

About -46db down from carrier, just 5 db out of spec from the QN8007 saying -50dB, that could be a lot worse.

Not so bad after all.

And noise is about 10Mhz on airband side...
https://ibb.co/j8fBZbh

i am not very good at interpreting these sorry.. but the noise mountain looks -55 to -85db lower than carrier ?
I cannot understand the 50Mhz thing you mention as I cannot understand the centre/span stuff sorry.

Running as a 1-2 Watter would likely be fine, do the spurs change much with reduced power that would be interesting.

You say it is not good, and it looks worse for sure than Chiense spectrum analyzser, but for what they are, chip based tx it does
not look that terrible for occasional low power use if anyone really wanted. I never saw any tower block rigs analyzers in UK. I bet they can be
from excellent to terrible as well.

At the end of the day you have to choose something that works for what you want to do which is always illegal of course. You can pay a high price for supposedly clean - but unverified by analyzer Euro kit like PCS - I never saw any analyzers of them myself so they could be just as bad for all I know. And then you have to pay a high price for all the bits on top, and it is a pcb and you have to build it up in a box connect it all up then it does not get modulated properly, that is my experience anyway with the 2015. And then it is mono etc

Make your own decisions. And probably just enjoy some other hobby or activity anyway. less risk as much fun and better use of time.

[EFR]

Would measure one, but im not located in UK.

[EFR]

About -46db down from carrier, just 5 db out of spec from the QN8007 saying -50dB, that could be a lot worse.

Not so bad after all.

And noise is about 10Mhz on airband side...
https://ibb.co/j8fBZbh

i am not very good at interpreting these sorry.. but the noise mountain looks -55 to -85db lower than carrier ?
I cannot understand the 50Mhz thing you mention as I cannot understand the centre/span stuff sorry.

That peak there https://ibb.co/Dtw4M5b

[FMEnjoyer]

Thanks for doing it as other said, not superb but not terrible either for low power use. No way run it at max power.

Is that peak at 50mhz +15 or -10 ? it has a very thin line going upwards as well.

That is much more worrying if at +15

The main carrier does not have that very thin line going up, though it is on line that represents measurement segment so i cannot be sure.

[FMEnjoyer]

please refresh and I wonder what oazzz has to say about these findings as he said his one was nice and clean, this shows not.

[EFR]

As you can see it is +15dB, and there is 5dB attenuator before spectrum, so its +20dB...

[FMEnjoyer]

If it is so then I am wrong and it is terrible. I admit to be wrong, then it seems no chinese tx can be trusted at all.
It is a shame they are so bad really, but on the other hand it saves getting nicked for basically nothing. There is nothing to be a pirate for anymore.

It's dead once and for all. And that is a positive as everyone can let it go for what it is, a subversion in the past except for the
final few.

Bye everyone, have a good life.

[yellowbeard]

The principle of all that stuff in one chip is not sound, I did try to explain why but I just got flamed for it.
There may be a way to Gunther a solution if you really wanted to use those chips, put it on a different frequency in a screened box with an FM receiver and use the receiver to modulate a clean exciter. This would retain the stereo and audio processing and the other woo-woo features and do away with most of the RF spurri apart from the stuff in close to the carrier, you would still need another PLL - but there may be a way around that too. That's just thinkin' and bullshittin' from me, what would I do ifn I had one of them...

[Albert H]

To be frank, the stereo coding and compression on those ICs is usually pretty poor too. They're fine for their intended use, but that's it!

Just for the sake of amusement, I priced up the components for a basic stereo limiter, stereo coder, and a 1 Watt exciter. Neglecting the PCBs (I'd get them made at JLC), the whole lot would come to around £23 if you shopped carefully. Most of the components would be available from CPC, Farnell, Mouser or more. You'd have to make your own inductors.

The only problem is calibrating the thing - minimising harmonic outputs and getting the deviation right.

[shuffy]

Just for the sake of amusement, I priced up the components for a basic stereo limiter, stereo coder, and a 1 Watt exciter.

Are those published designs people can look up Albert

Before Christmas I had 3 weeks spare and picked up an exciter design I'd started a few years back. I just costed it - £28! Back to the drawing board?

[Albert H]

Not at all. Your circuit was probably more sophisticated.

The circuits I used were my four-IC PLL, a Colpitts oscillator, balanced doubler, and an output stage using a BF199 into a 2N4427. The stereo coder was based on the NRG Pro III coder, but with a better output filter, The stereo limiter used a TL074 quad op-amp, a couple of transistors and a pair of LCR0202 vactrols. I use a 4MHz reference crystal (cheap as chips!), and all the coils are hand-wound. The most expensive single component is the 2N4427 - you have to shop around to find genuine ones!

[jvok]

How about rd01hvf1? Will do 5-6w for same drive power 2n4427 takes to get to 1w and is only a couple quid more. Plus you can actually buy them easy enough without worrying about knockoffs

[zulu53]

Do you mean RD06HVF1? I have never heard
about RD01HVF1. However, RD01MUS1 is a 1.4W device.