Ah fair I thought it came from the seller like that

Might take an moment to get there, they might given me wrong trackingnumber or it is in wrong country....

Hmm, that parcel started from China, went to France then to the Italy, then to the Germany, Denmark, Netherlands and now it is in Norway.

I might just order second one, that first one might not survive that trip...

Got it today, I measure it on next week when I have time.

Dude, this thing is same size as topcap of Eimac 4CX5000A...

FMEnjoyer wrote: ↑Sun Feb 09, 2025 6:12 pm I am having a bit of trouble to understand this... did you remove the output transistor to run low power ? Then went for a walk with the transmitter with you with wire for an antenna ? And it works off 3 volts I thought they are 12v. I wonder what the trimmer thing does on it ?

Amazing you could hear it 1 mile away with just a bit of wire hanging out your pocket.

sorry I don’t always look at things, yes I removed the output transistor, it would of been a fraction of a watt, had in a small black plastic box, it was powered off 2 or 3 aa or aaa batteries don’t remember now. I had a wire hanging down from it, used another attached to the headband of some old headphones. I went and reviewed the recording when I got back home, I was surprised to hear it part of the song, but only for a few seconds. I kind of suspect the power of it wasn't much more than an in car transmitter, they don't have a wire dipole.
The actual fm chip works off a lower voltage, so you have a drop down regulator which drops the voltage down from 12v to 5v, it can work a bit lower. The green trimmer is to a just the biasing, it will lower or make the rf go higher on a given frequency.

Thanks northeast.

I completely forgot to mention: Some germans already tested the 7w unit.
Have a look at this, second page: http://saba-forum.dl2jas.com/index.php/ ... M-exciter/

Nonetheless, I'm still curious for your test results EFR

BlackBeard wrote: ↑Fri Mar 07, 2025 11:10 pm I completely forgot to mention: Some germans already tested the 7w unit.
Have a look at this, second page: http://saba-forum.dl2jas.com/index.php/ ... M-exciter/

Nonetheless, I'm still curious for your test results EFR

Thanks Blackbeard. Interesting for sure, I wonder if the QN8066 was the one that Albert had that worked well. He said 8007 but maybe that was a typo ? As the German forum states the QN8066 is the better of the 2 boards out there, with the one with no data card having another inferior chip.

Hope this works to translate for non German speakers like myself scroll about 3/4 page down for the 7W QN8066 one. Northeast did you get your removal of power transistor from that site ? The German guy "castrates" it translated that means cutting off the balls .

https://saba--forum-dl2jas-com.translat ... r_pto=wapp

I've tried both ICs - 8066 and 8007. The '66 is surprisingly good for its price. I still wouldn't consider using it for anything other than very low power in-car transmission to play an mp3 or CD player into the car radio (their intended purpose).

These things really are toys! They cannot be considered for serious use. There are cheap, good quality options around - look at "Zozo's" exciter, for example. It is relatively easy to construct, and the results are excellent. Granted that if you want stereo there's a bit more work to be done, but basic stereo coders are capable of good results, and don't cost too much to construct.

To complete your small stereo transmitter, you'll need a stereo limiter to prevent over-deviation. There's no simple, cheap option that's widely available, except (perhaps) the "Pira" circuit. Jan combined a lot of funtionality into a fairly simple circuit, but it's easy to set it up to sound very bad, and getting good stereo matching is tricky.

I plan to put a reasonably simple, cheap split-band limiter on here in the near future. I want it to use standard, easily found components (no exotic, expensive attenuator ICs), and I plan to include 15kHz lowpass filtering on the same board, and the attenuators will be switch-mode, ensuring accurate channel matching. The board will contain quite a few dual op-amp ICs, but I plan to use TL072 for most parts, with a couple of NE5532 at critical points. The switch-mode "clock" will operate at a multiple of 19 kHz to prevent beat products with the audio.

As an aside, my latest commercial design uses two oversampled switching multiplexers - one at 38kHz (as usual) and one at 114kHz which is attenuated, inverted, and mixed with the 38kHz one in just the right amount to cancel the (predominent) 3rd harmonic, without the need for really tight filters (that always upset the phase accuracy of the "S" component). The separation from the prototype is exceptionally good, with very low distortion and noise.

Albert H wrote: ↑Sat Mar 08, 2025 12:43 pmI've tried both ICs - 8066 and 8007

Albert do you mind if I ask why out of curiosity? Presumably not free radiating!

Headphone users get an 8066 not a bh one for round the house

I will measure that little thing on this week, joint pain in hands make soldering hard.

i hope you get well EFR

shuffy wrote: ↑Sun Mar 09, 2025 4:13 pm

Albert H wrote: ↑Sat Mar 08, 2025 12:43 pmI've tried both ICs - 8066 and 8007

Albert do you mind if I ask why out of curiosity? Presumably not free radiating!

One of our guys had an in-car transmitter that used the 8066, and I found a junked board with the 8007 on it, and we tried both into resistive loads on the bench. We were interested in seeing just how far the technology had come since the early chips (like the Rohm BA1404).

The 8007 was pretty clean, as long as the supply voltage was kept to 3.3V. The 8066 was similar (not quite as clean) but allowed RDS. Again, the supply had to be kept low.

Please remember the use these things were meant to be used for - they were NOT meant to be amplified. Please DON'T consider using one of these in a serious rig. You'll get nicked because of the interference it'll cause!

Albert H wrote: ↑Thu Mar 13, 2025 11:39 pmPlease remember the use these things were meant to be used for - they were NOT meant to be amplified. Please DON'T consider using one of these in a serious rig.

Not a chance. My views on this are well documented in other recent threads...

I did set it to an 100Mhz, in 5mins it went from 99.96 to 100.070, output power did rise same time from +4.4dBm to around +9.5-10.5dBm.

Bluetooth audio is mono on my unit, line and usb audio are stereo, all TTL level serial commands work, MCU on board dont support RDS.

Audio is very mufled when using bluetooth or linein, on soundcard mode its quite ok.

Powered from linear 5V supply.

Nice toy to mess around, just solder 1W 47ohm resistor to antenna output....

I have a QN8066 5/7Watt much to my embarrassment. To remove the big final transistor and use the tiny one which I presume is the SMD, could someone be as kind as to explain the "castration" technique please, how do I route the small transistor output via the coils to the BNC out thus removing final amplification stage and maybe getting 100mw out of it ? Just for a little fun with soldering iron, otherwise it is going in the bin.

Blue peter time, if you’ve taken out the output device which is screwed to the heatsink, by either chopping the legs off or desoldering it, I think you’ll have 3 connections, 1 should be ground, it would be connecting the other two together that aren’t connected to ground with a short wire. I’ve not had any of these for a while, others might know better.

thanks northeast I will give it a go. Even brought down to the lowest power I can 300mw or so with the final in circuit, the band noise is a disaster, unusable. I wonder if removing final stage will quieten it, worth trying otherwise I will toss it, no great loss. I am trying to keep the small smd transistor output going through the coil arrangement, i appreciate there it no power tweak option but i am guessing each stage of gain is a potential for more crud coming out on these things. Barely worth the time but one last shot.

shuffy wrote: ↑Sun Mar 09, 2025 4:13 pm

Albert H wrote: ↑Sat Mar 08, 2025 12:43 pmI've tried both ICs - 8066 and 8007

Albert do you mind if I ask why out of curiosity? Presumably not free radiating!

No. Into a loading resistor.