• D5W 76-108MHz 500mW FM DykbRadio

Posted: **Fri Oct 04, 2024 10:31 am**

https://dwmzone.com/en/raspberry-pi/105 ... splay.html
D5W 76-108MHz 500mW FM radio Transmitter DykbRadio, 4pcs 105e free shipment

Is possible get part list? or only for one which is erased?

D5W 76-108MHz 500mW FM radio Transmitter-2000m FM and stereo transmitter with digital display.

Power supply requirements:
0.5W FM radio transmitter uses USB Type C interface for power supply, with power supply voltage of 5V and consumption current of no more than 500mA.

Input audio signal:
3.5mm stereo audio socket,3.5mm male audio cable is required.

Transmitting interface:
The transmitter side is SMA female head with external thread and internal hole. SMA male head and signal wire of internal thread shall be used for connection. The characteristic impedance of the signal line is required to be 50 ohms, Teflon material is recommended, the recommended specification is 50-3, and the line length is not less than 2 meters.

Antenna requirements:
the working frequency should be 50 ohm pure resistive load, and the VSWR should not be higher than 1.5.

Note: Since the transmitter's transmission power is 0.5W, the transmitter will not be damaged in the total reflection state, so the requirements for the antenna are not high. The more qualified the antenna is, the farther the transmission distance is.

Description of operation sequence:
1. Connected to antenna

2. Connected to power supply

3. Connected to audio input

Panel description:
The panel includes the following factors:

LCD display window

Key

Red LED indicator

Top SMA interface antenna base

Top audio input socket

USB-C power socket.

KEYS:
DW (step):
The default state is to lower the frequency (DW) and step to 0.1MHz. When the frequency drops to 76MHz, it will automatically cycle to 108MHz.

Press and hold the DW key for 3 seconds to switch to 1MHz step and the LED is on for a long time.

Press and hold the DW key for 3 seconds again to switch back to 0.1MHz step and the LED is off.

UP (res):
The default state is up regulation (UP) and the step is 0.1MHz. When the frequency rises to 108MHz, it will automatically cycle to 76MHz.

Frequency reset:
press and hold the res key for 3 seconds, and the output frequency will automatically return to 90.00MHz. Each time you press the key, the LED will flash. Five seconds after the operation of all buttons is stopped, the led flashes, the machine saves the current working frequency, and the next time the machine is powered on, it will automatically work at the saved frequency.

Audio input:
The input audio volume should be adjusted according to the radio reception effect, so that the sound is clear without distortion.

Power input:
5V power supply, the maximum is not more than 5.5V. If the maximum working voltage is exceeded, the transmitter may be damaged.

Use a mobile phone charger with a USB type-c charging cable. The charger should try to use products with low ripple and low noise, so that the output signal quality of the transmitter is better.

Posted: **Fri Oct 04, 2024 3:55 pm**

You can get them on Aliexpress for cheap... they use the QN8027 which is pretty bad - I think that was the one with the double carrier.

Posted: **Sat Oct 05, 2024 6:18 pm**

Yes - they're really horrible. There are images 7.6 MHz either side of the carrier, and the stereo coder adds endless spurs too. Once again, someone is amplifying one of the horrible "audio sender" chips, and creating a nasty interference generator.

Posted: **Sun Oct 13, 2024 12:56 am**

Albert H wrote: ↑Sat Oct 05, 2024 6:18 pm Yes - they're really horrible. There are images 7.6 MHz either side of the carrier, and the stereo coder adds endless spurs too. Once again, someone is amplifying one of the horrible "audio sender" chips, and creating a nasty interference generator.

I've had some luck experimenting with those cheap small QN8027 boards sold all over amazon (not the whole unit OP posted) using the 24MHz quartz oscillator running them into a 3 pole band pass but they still let a lot of junk through around 2MHz wide even with that. If using this bare minimal bp filtering it's almost good enough for very low power operation but definitely not watts of power.

Another issue is the stupid crystal on most of them is usually 25kHz off frequency but can be pulled into <200Hz of operating frequency by placing a variable capacitor of around 30pF in parallel with the crystal which is very hard to solder on considering the tiny SMD parts.

Currently working on a 7 or possibly 9 pole bpf just to see if it's possible to polish up the turds. Given the insertion loss with so much filtering it's almost pointless though since for the cost and time spent building a nice narrow filter doesn't outweigh building a proper synthesizer that would outperform it anyway.

I'm only doing this just for the fun of it to see if it's even possible to make it passable for localized community broadcasting at low power.
I always suggest to never amplify these things at any decent power because there is no amount of filtering that will really cut it even with the better respected QN8066 and the likes.

I believe with tight filtering they can be made usable for low power broadcasting within reason, or if anything will beat the pants off of running them directly which trashes half the FM broadcast band around your signal. This of course requires tight bandpass filtering, tuned RF stages after it and then lowpass filtering on the output and a tuned antenna system, and even then.. good luck.

Posted: **Sun Oct 13, 2024 2:50 am**

You're really just trying to polish the unpolishable! It's a quick way to wipe out the band in the vicinity of the rig, and get an "unfreindly visit"!

If you consider that it's trivially easy to generate 500mW of clean RF, and you can build a simple PLL using a few cheap 74HCT CMOS ICs, and a basic stereo coder isn't difficult, there's no point whatsoever in trying to clean up one of these "audio sender" ICs.

Posted: **Sun Oct 13, 2024 4:19 pm**

Albert H wrote: ↑Sun Oct 13, 2024 2:50 am You're really just trying to polish the unpolishable! It's a quick way to wipe out the band in the vicinity of the rig, and get an "unfreindly visit"!

If you consider that it's trivially easy to generate 500mW of clean RF, and you can build a simple PLL using a few cheap 74HCT CMOS ICs, and a basic stereo coder isn't difficult, there's no point whatsoever in trying to clean up one of these "audio sender" ICs.

I fully agree but finding some of the 74 series logic and prescaler here isn't that easy these days, and this is partially a project for me to learn RF filter design...

As I stated my uses for filtering such a gadget is strictly for localized community broadcasting, not covering a town or vast area, and then amplify it back up to a usable level after the insertion loss of the filtering but not a lot beyond the original power output. Good low pass filtering will be employed after its final class C stage.

I have ten 3.5-13pF NP0 variable capacitors I bought to experiment. My first idea is to use a 5 pole BPF.
With even the 3 pole one I am testing that I rigged up recently it has a striking usability by not wiping out stations a channel up or down from mine outside of my property while still having good range for a few dozen milliwatts after amplification, and it's "Q" factor isn't even that great because I used ferrite slugs for coils. I can't say the same running without any BPF which is horrendous from these QN chips.

I question if a 7 pole is that much greater than 5 or 6, but there is definitely a huge jump between 3 and 5 pole in simulation. Will be a nightmare to tune up each time it's pushed into service on a different frequency but making for a fun late night project and besides even if I eventually give up on these chinese all-in-one transmitter ICs I will have still built a cool BPF for other FM transmitter projects

BTW sorry if I derailed the thread some. Current project of mine for fun and I don't see a lot online from others who have tried this.

Posted: **Mon Oct 14, 2024 8:26 am**

rigmo wrote: ↑Fri Oct 04, 2024 10:31 am https://dwmzone.com/en/raspberry-pi/105 ... splay.html
D5W 76-108MHz 500mW FM radio Transmitter DykbRadio, 4pcs 105e free shipment

Is possible get part list? or only for one which is erased?

D5W 76-108MHz 500mW FM radio Transmitter-2000m FM and stereo transmitter with digital display.

Power supply requirements:
0.5W FM radio transmitter uses USB Type C interface for power supply, with power supply voltage of 5V and consumption current of no more than 500mA.

Input audio signal:
3.5mm stereo audio socket,3.5mm male audio cable is required.

Transmitting interface:
The transmitter side is SMA female head with external thread and internal hole. SMA male head and signal wire of internal thread shall be used for connection. The characteristic impedance of the signal line is required to be 50 ohms, Teflon material is recommended, the recommended specification is 50-3, and the line length is not less than 2 meters.

Antenna requirements:
the working frequency should be 50 ohm pure resistive load, and the VSWR should not be higher than 1.5.

Note: Since the transmitter's transmission power is 0.5W, the transmitter will not be damaged in the total reflection state, so the requirements for the antenna are not high. The more qualified the antenna is, the farther the transmission distance is.

Description of operation sequence:
1. Connected to antenna

2. Connected to power supply

3. Connected to audio input

Panel description:
The panel includes the following factors:

LCD display window

Key

Red LED indicator

Top SMA interface antenna base

Top audio input socket

USB-C power socket.

KEYS:
DW (step):
The default state is to lower the frequency (DW) and step to 0.1MHz. When the frequency drops to 76MHz, it will automatically cycle to 108MHz.

Press and hold the DW key for 3 seconds to switch to 1MHz step and the LED is on for a long time.

Press and hold the DW key for 3 seconds again to switch back to 0.1MHz step and the LED is off.

UP (res):
The default state is up regulation (UP) and the step is 0.1MHz. When the frequency rises to 108MHz, it will automatically cycle to 76MHz.

Frequency reset:
press and hold the res key for 3 seconds, and the output frequency will automatically return to 90.00MHz. Each time you press the key, the LED will flash. Five seconds after the operation of all buttons is stopped, the led flashes, the machine saves the current working frequency, and the next time the machine is powered on, it will automatically work at the saved frequency.

Audio input:
The input audio volume should be adjusted according to the radio reception effect, so that the sound is clear without distortion.

Power input:
5V power supply, the maximum is not more than 5.5V. If the maximum working voltage is exceeded, the transmitter may be damaged.

Use a mobile phone charger with a USB type-c charging cable. The charger should try to use products with low ripple and low noise, so that the output signal quality of the transmitter is better.

I think there are two different versions of this, the one with display has the 8027 doesn’t do 0.5w, the one without a display has the 8066, it does 0.5w, mostly I use it for around the house with the telescopic antenna folded down, with an outdoor aerial you could probably hear it a few miles away. There are smaller ones not much bigger than the lcd screen they have the 8027, simliar to what you find in alot of in car transmitters, the frequency is nearly always off in the 8027.
The 8066 is better, you can already get 5/7w kits that have it in, no need for an amplifier, just need to match the aerial, the problem it would be hard to get the aerial far enough away, when i’ve tested them here it was knocking out even the strongest stations 12+ meters away from the antenna, with a pcs or nrg transmitter this would not happen at all.
The bh1471f is the best i’ve found for wideband noise, puts out alot less noise over the fm band, maybe due to the external coil setting the frequency, it can only be set to 8 frequencies. I think it is prone to picking up hum, the coil buzzers when I put my finger near it!, the 8066 is more robust, i’m not sure what the 1471f would do if it was connected to an amplifier..the pdf is available on the pira website it is interesting, you can turn the stereo pilot level completely off https://pira.cz/pdf/bh1417f.pdf
someone has written some software for the 8066, thought don't think it has any effect on the noise it puts out

D5W 76-108MHz 500mW FM DykbRadio

D5W 76-108MHz 500mW FM DykbRadio

Re: D5W 76-108MHz 500mW FM DykbRadio

Re: D5W 76-108MHz 500mW FM DykbRadio

Re: D5W 76-108MHz 500mW FM DykbRadio

Re: D5W 76-108MHz 500mW FM DykbRadio

Re: D5W 76-108MHz 500mW FM DykbRadio

Re: D5W 76-108MHz 500mW FM DykbRadio