Mast Mounted 2m Preamplifier Recommendations......

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by K3GM, May 25, 2015.

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  1. K3GM

    K3GM Ham Member QRZ Page

    I'm interested in adding a GaAsFET preamp at the mast for a weak signal 2m yagi. The location of a new tower requires a run of 165' of LDF4-50. I was looking at the Advanced Receiver Research, MSP144VDG-160 mainly because the description leads me to believe that it is RF switched. The plan would be to power the unit by injecting the supply voltage onto the Heliax via bias-T's. Does anyone use this brand of preamp or can you make any other recommendations based on your experience with them?
     
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    Looks like power is provided by a separate power cable input.

    I would not try to Power it over Coax. Unless you use their injector, You can not just T it.


    Good Luck on your project.
     
  3. W6RZ

    W6RZ Premium Subscriber QRZ Page

    Advanced Receiver Research has been around forever. I think I bought my first preamp from them in 1983. It's a solid company. I'm sure the MSP144VDG-160 will work well for you.

    @KA9JLM. You can power anything with two bias tees, one in the shack and one on the tower. Or the ARR preamp can be ordered to accept power from the coax. You don't have to use their "injector". A bias tee and and an "injector" are the same thing.

     
  4. KC4YLV

    KC4YLV Ham Member QRZ Page

    if I was running a setup hot enough that i was buying $1.50 a foot feedline, I would not muck it up with bias tees. Do a run of outdoor rated low-voltage wiring up there parallel to the coax. If you run extra conductors, you'll have future expansion capability for extra coax relays, polarity switches, so on.
     
  5. W1GCI

    W1GCI Ham Member QRZ Page

    I suspect that you don't really need the gain from the amp to overcome some deficiency in your rig, so with about a 1.2DB loss in the cable, I don't think you gain enough from a noise figure perspective to warrent adding a preamp. The added loss from the added connectors to tie in the preamp will wash out just about everything you may be gaining. Additionally, you'll be limiting your transmit power to just 160 watts with the preamp in line.
     
  6. W6RZ

    W6RZ Premium Subscriber QRZ Page

    An issue with the bias tee approach is finding one that can handle more that 50 watts.
     
  7. KB1PVH

    KB1PVH XML Subscriber QRZ Page

    I have a 144 and 432 version and power is fed up the coax from my IC-9100. When you order it, you need to specify that's how you are going to power it and they put a choke in it, but if you change your mind and want to power it from the external connector you need to remove the choke or it will send power back down coax.

    Dave-KB1PVH
     
  8. W0AAT

    W0AAT XML Subscriber QRZ Page

    Connector loss will be far less than 1db! if it is over .1 I would be buying new connectors! And on weak signal modes that 1db may make the contact so a preamp is very valid. If you can run split receive from the radio you can run quad shield RG6 after the preamp to the radio. Cuts down on number of relays in line.

    You will need to run a key line to the preamp, rf switching on SSB/CW = blown preamps and fried relays
     
  9. KA9JLM

    KA9JLM Ham Member QRZ Page


    That makes sense and may be the reason they recommend the use of their injector.

    Does the
    external connector provide a way for PTT, so RF keying is not needed ?


    73
     
  10. KA2BPP

    KA2BPP Premium Subscriber QRZ Page

    yes it does. can't find my manual or I would tell you the pin. memory not working today
     

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