K1DEU
160 ft Rohn 45g Tower
Premium
join:2007-10-30
Stamford, VT
4 edits | Eliminating Feedline and Connector loss + CA-819 Pictures
If we use a Receive, post or pre-amplifier at a remote antenna (many coax or feedline feet away from our modem)which has a noise figure/temperature the same or better than our modem receiver we can eliminate all feedline/connector losses on receive. My favorite device to do this is a Cyfre CA-819 bilateral dual band amplifier modified to function outside with remote DC power. This Cyfre has 12 DB of receive gain to easily overcome most any feedline and connector losses and establish a quieter receiver noise figure than either my Sierra 881 or 597 modems. It has plenty of gain to more than over come transmit losses also!
When terminating my second hand $80 Cyfre CA-819 bi-lateral dual band amp I come out of the amp on the tower top into this Splitter then into my 5 foot long Stainless Steel yagi on 850 MHz and 1900 MHz Grid. For individual aiming I use their 50 Ohm terminating dummy load. I leave the amp on 24/7 so condensation will not collect inside by running +24 VDC up the tower to it in a cheap Rubbermaid case with weep holes in the case bottom! Its neat to have all the 200 foot LMR 400 RF line and connector loss eliminated!
»www.hyperlinktech.com/productfam···x?id=180
I have decided to remove the Internal antenna splitter in the Cyfre CA-819, add another antenna connector and label the (now) two antenna connectors 850 MHz and 1900 MHz. This way I will not be going through two splitters one internal, one external to feed the separate antennas nearby. A lot less loss = better noise figure receiving, etc...
Not many splitters are weatherproofable with 20 Db isolation and .5 Db loss. These are also excellent combiners to stack two antennas together. Regards John
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K1DEU
160 ft Rohn 45g Tower
Premium
join:2007-10-30
Stamford, VT
2 edits | Re: Eleminating Feedline and Connector loss + Splitters
The CA-819 Dual Band Bi-lateral Amp inside. I will add a chassis mount antenna connector to the upper left for 1900 MHz Antenna the original connector at top right will go to the 850 MHz antenna and I will remove the little internal lossy splitter which is right below the original antenna connector at top right.
The two modules at left are for 1900 MHz and are both marked
R DFX1880J1960Q T.
while the two modules at right are for 850 MHz and are both marked R DFX0836H08816 T.
I will be leaving both bands powered up/on for now
I will also replace the type "N" 8-28 VDC power in connector at bottom right and decouple it more inside so I may run DC power up to the amplifier with unshielded cable. My low frequency Ham 160 and 75 Meter antennas are nearby where I run 1500 watts PeP. Not that it matters but I operate old fashioned AM not SSB on these ham bands.
Better than Mil Spec Quality through out ! Regards John
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