Bias-T Recommendation

[Dominic1967]

I have a broadband active antenna from Cross Country Wireless that is rather tailored towards use with SDRplay products that have an internal 5V bias-t. Works very well, but I'd like to use it with other receievers, even perhaps as a "noise" antenna with my MFJ-1026. Is there such a thing as a commercially available bias-t that outputs 5 volts? I'm having a hard time finding one that isn't 12V and I'm not sure I'm clever enough to build my own.

Thanks,
Dominic

 

[Ubbe]

It's just a capacitor to stop DC to go to the receiver and a coil to stop RF from being shortcircuit by the DC source, nothing critical if not going higher than 1GHz. You can connect that to any voltage so just match it with what the amplifier needs. Don't pay too much and connect to any USB charger you have to use at 5 volt when using a USB cable that you solder or screw to the bias-T. Cables sometimes isn't following color standards red=positive, black=negative as wires are hidden so measure first.

Amazon.com : bias-t

/Ubbe

 

[prcguy]

Get a passive Bias T and seperate 5v linear wall wart power supply. Something like this will work for VLF/HF and the power supply is too expensive but at least you can see a linear type is larger than a switching type.

0.2‑180MHz Bias Tee Module RF Microwave DC Blocker Filter Board Electronic WT | eBay

WIDE RANGE: The wide frequency range from 0.2 to 180MHz ensures effective clutter filtering, very practical. RF+DC: RF DC bias (this port can transmit RF and DC bias). LOW LOSS: This bias tee module enables low loss, 0.1dB at 1MHz and 0.4dB at 100MHz, promising signal quality.

www.ebay.com

5v 1.5 amp linear power supply 5.5mm x 2.5mm connector | eBay

I used this with a squeezebox.

www.ebay.com

 

[K4EET]

<snip> Is there such a thing as a commercially available bias-t that outputs 5 volts? <snip>

They are out there. Here is one example of a 5 VDC Bias-T device.

TW155 Bias-Tee (5V) - Calian Space (GNSS)

The TW155 is a professional grade wideband Bias-Tee for injecting DC voltages onto coaxial lines. Features Low insertion loss: less than 1 dB at 3 GHz Regulated output voltage: 5 VDC 0.5 to 3 GHz operating frequency Low insertion loss 1 dB @ 2 GHz VSWR < …

www.calian.com

Not the cheapest when compared to DIY per the above.

 

[Dominic1967]

Get a passive Bias T and seperate 5v linear wall wart power supply. Something like this will work for VLF/HF and the power supply is too expensive but at least you can see a linear type is larger than a switching type.

I'm actually pretty well stocked up on overpriced 5V AC adapters. I have Jameco and Meanwell models, all linear and regulated. So I'm good, there. I see that bias-t, or at least dozens that look like it all over the internet. I guess I never realized there was a such a thing as a passive model. It simply outputs what voltage you feed it?

 

[prcguy]

I'm actually pretty well stocked up on overpriced 5V AC adapters. I have Jameco and Meanwell models, all linear and regulated. So I'm good, there. I see that bias-t, or at least dozens that look like it all over the internet. I guess I never realized there was a such a thing as a passive model. It simply outputs what voltage you feed it?

Yes and as someone else mentioned you can make one cheap. Break the center of the coax and bridge with a .05uf disc cap. Then feed voltage to the antenna side of the cap with a 100uh choke and bypass the power supply side of the choke with a .01uf disc cap. Cap values are close and I would have to look it up to make sure.

 

[Ubbe]

Only critical component are the choke as its layers of copper wire acts as a capacitor between windings so probably wise to not use a too high inductance or try and get one as big as possible in size, that might indicate it is loosely wound or have thick enamel isolation. But I would guess it only comes into play at GHz frequencies. As long as the bias-T are specified to handle the needed current it should be okay to use.

/Ubbe