Has "the blue stick" bias power option?

[MaiKeeReis]

Dear friends,

could any of you please teach me, if the depicted stick should have switchable BIAS power or not?

I asked the trader, but he barely understood my question. He promised to ask techn staff, but I did not got any reply since then.

BIAS power is never available, regardless of FEEDER_BIAS_POWER setting.

With FEEDER_BIAS_POWER=OFF, I get:

ultrafeeder  | s6-rc: info: service 09-rtlsdr-biastee: starting
ultrafeeder  | [2025-02-17 22:56:10.794][09-rtlsdr-biastee-init] Device type is rtlsdr, checking for bias tee...
ultrafeeder  | [2025-02-17 22:56:10.906][09-rtlsdr-biastee-init] Disabling bias tee...
ultrafeeder  | [2025-02-17 22:56:10.919][09-rtlsdr-biastee-init] Found 1 device(s):
ultrafeeder  | [2025-02-17 22:56:10.941][09-rtlsdr-biastee-init]   0:  Realtek, RTL2832U, SN: 00001000
ultrafeeder  | [2025-02-17 22:56:10.941][09-rtlsdr-biastee-init]
ultrafeeder  | [2025-02-17 22:56:10.949][09-rtlsdr-biastee-init] Using device 0: Generic RTL2832U
ultrafeeder  | [2025-02-17 22:56:11.210][09-rtlsdr-biastee-init] Found Rafael Micro R820T tuner
ultrafeeder  | s6-rc: info: service 09-rtlsdr-biastee successfully started

with FEEDER_BIAS_POWER=ON, I get:

ultrafeeder  | s6-rc: info: service 09-rtlsdr-biastee: starting
ultrafeeder  | [2025-02-17 23:22:35.323][09-rtlsdr-biastee-init] Device type is rtlsdr, checking for bias tee...
ultrafeeder  | [2025-02-17 23:22:35.425][09-rtlsdr-biastee-init] Enabling bias tee...
ultrafeeder  | [2025-02-17 23:22:35.442][09-rtlsdr-biastee-init] Found 1 device(s):
ultrafeeder  | [2025-02-17 23:22:35.461][09-rtlsdr-biastee-init]   0:  Realtek, RTL2832U, SN: 00001000
ultrafeeder  | [2025-02-17 23:22:35.461][09-rtlsdr-biastee-init]
ultrafeeder  | [2025-02-17 23:22:35.472][09-rtlsdr-biastee-init] Using device 0: Generic RTL2832U
ultrafeeder  | [2025-02-17 23:22:35.731][09-rtlsdr-biastee-init] Found Rafael Micro R820T tuner
ultrafeeder  | s6-rc: info: service 09-rtlsdr-biastee successfully started

Thank you for reading!

[wiedehopf]

@MaiKeeReis

switchable BIAS power

None of the SDRs with LNA + filter have a biastee.

[astrodeveloper]

I had to use a separate Bias-T circuit board to provide power to other devices. This is one of them via Amazon, but any similar board should work well also. Amazon.com: Taidacent DC Feed Bias Tee RF Microwave Bias Active Antenna Power Supply Mains DC-Blocker 10-6000MHz Amplifier DC Bias : Electronics

[MaiKeeReis]

@wiedehopf

None of the SDRs with LNA + filter have a biastee.

Thank you again for answering my questions!

[MaiKeeReis]

@astrodeveloper

I had to use a separate Bias-T circuit board to provide power to other devices. This is one of them via Amazon, but any similar board should work well also.

I own a very similar one, with micro-USB socket and 5V supply.

So, with long cables (have an 3 m antenna mast and two more meters to the IT box) I will need a second one to tee out the power, and feed the LNA, okay so far.

This brings me to the next question: Any proposal for an inline amplifier which does not need to split out the bias power with an separate Tee, but doing the split itself?

Or with other words, it there any chance to find an LNA which combines both the pictures I am presenting here?

Many thanks!

[chrislfa]

The Uputronics ADS-B LNA supports operation from the bias-tee input directly.

If you’re asking whether there is a LNA which can then provide a further output for that so that you can go on to power other devices, I’ve never seen anything like that. In that case using the separate splitter as you describe, to power both the LNA via its dedicated Vin, and power the other devices, makes more sense.

[MaiKeeReis]

GREAT!
Exactly what I was looking for. And it is not necessary to build an RF-tight housing.

THX

[chrislfa]

I’ve got one of these and their previous model too, and they both work really well. I don’t use the bias-tee as it’s indoors so within reach of a short USB cable, so I power it from a port on the Pi. I’ve a friend who has their older model on the roof and his is powered by this bias-tee unit suggested by Uputronics, with around 5m of LMR400 between them. It all works fantastically.