DC block and Tee adapter configuration for phantom supply?
http://www.microwave.gr/content/view/229/31/
and I would like to have a phantom supply for the LNA (supply voltage through the same rf coaxial cable).
Is my configuration of the DC blocks and the Tee adapters correct?
I am wondering about the Tee adapters losses as well as the DC blocks power handling capability.
Tee adapters I am using: http://www.ebay.com/itm/Omni-Spectra...ht_1850wt_1085
DC blocks I would like to use: Mini Circuits, P/N BLK-18-S+ 0.01 to 18 GHz/Low Loss
The device you need is a "bias T". These are basically diplexers and will have 3 ports: "DC in", "RF+DC" and "RF". They will have a dc blocking cap on the "RF" path. Mini-Circuits (and others) sell integrated bias Ts that may work for you.
http://www.minicircuits.com/products...ees_coax.shtml
I see two Ts in your diagram, but there's no path in your sketch for current to get to the LNA?
hello,
I have separated the T and the dc-block, instead of buying a bias-t. the t adapter I use is just connect the dc to coaxial without using any internal coil like a bias-t would do. can I use just a bias-t on the lna side and then just a dc block and a T adapter on the receiver side, or do I need two bias-T?
That SMA tee is going to have a very poor flatness on the thru RF path. At some frequencies, the port going to the DC supply will will act like a quarterwave stub going resonant. That will cause a deep notch in the insertion loss and loss at the adjacent frequencies.
You want a true bias-tee device, such that the AC block (inductor) is located directly on the RF line (electrically, very short).
http://en.wikipedia.org/wiki/Bias_tee
can I use just a bias-t on the lna side and then just a dc block and a T adapter on the receiver side, or do I need two bias-T?
That depends on the DC biasing requirements of the LNA. Look at the spec sheet, it should tell you if you need to supply DC to both the input and output of the LNA. What LNA device are you using? (make/model #)
please see this url. http://www.microwave.gr/content/view/229/31/ I have updated it with photos from the lna head, which is composed of different parts. the relays require 24v whrereas the amplifiers require 15v, which will be supplied by an on-board regulator.
Please post the part number or datasheet of your LNA.
Typically, dc power is fed into the amplifier on the "RF out" pin of the amplifier. In this case you would just need one bias tee, where "RF+DC" of the bias T would be connected to the "RF out" of the amplifier.
this is the amplifier http://www.ebay.com/itm/JCA-812-286-...item2c648dec31 but since the head has other components on it (relays and second preamplifier) I think I need two bias-T.
have yo got any specs for the Agilent 33150A bias-T? basically the max current.
Your LNA has a discrete pin for Vcc. So you can't feed the power directly through the coax into the LNA. You can still run the DC power up the coax and then wire it over to the pin. In this case you still use a bias T but attached differently.
Connect the "RF" port of the bias T to the "RF out" port of the LNA. "RF+DC" will be facing away from the LNA. Then jumper two wires from the "DC" port of the bias T to the Vcc and ground pins of the LNA.
Yes, I am going to use exactly this configuration. I will correct the transceiver diagram. bias-T are not so inexpensive as I thought though and I am going to need 2 of them, one for the lna and one on the other end...