2 Meter & 450mHz Brick Amplifiers- Short take

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, Jun 23, 2019.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    This one certainly does: http://www.rmitaly.us/index.php?main_page=product_info&products_id=134 (200W amp for 2 meters.)

    I have one, it's very sophisticated. SWR "protection" was easy since the unit has a built-in directional coupler measuring forward and reflected power; its front-panel LCD indicates drive power, output power, SWR and heatsink temperature.

    They should "all" do something like that. Actually, some old Tokyo Hy-Power VHF-UHF amps did! -- but they're gone.
     
    W1BR likes this.
  2. KX0Z

    KX0Z Ham Member QRZ Page


    4 or 5 of them on ebay now, not cheap.
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I didn't look, but not surprised -- they were expensive when they were new!
     
  4. KM3F

    KM3F Ham Member QRZ Page

    For SWR and overdrive trip, look at the Mirage B2518 G.
    Has a fault LED on the front panel.
    Kicks out the keying relay on fault detection. Locks out until a power down re set is done.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The old Mirage (tan/brown faceplate) B2516 was a very good amp.

    However I've had to repair several of the "newer" B2518Gs, which I think is really the same circuit just re-labeled by MFJ and now the faceplate is black.

    The repairs all involved replacing the PA transistors (usually not the driver, just the two output devices) due to overheating to destruction, so there isn't really any overtemp protection to speak of. These amps need a fan or two blowing across the heatsinks for any kind of heavy-duty use (which would mostly be "FM"). On SSB they seem okay.

    The transistors aren't difficult to replace, but I'd still recommend "anybody" using one of these on FM, or maybe in a contest where they do a whole lot of transmitting on SSB without breaks: Put a fan on it.:p

    One of the impressive things about the new RM Italy 200W 2m amp is it not only contains several sensors and a real directional coupler with an LCD display to let you know what's happening, but it also has two cooling fans embedded in the heatsink fins: Very difficult to overheat it. Worth the extra $.
     
  6. WA8UEG

    WA8UEG XML Subscriber QRZ Page

    I have owned quite a few brick amps but by far the TE Systems is the best in my opinion. On 2 meters 10W in gives me 320W out and runs very cool. I bought it used 2 years ago and use it a few times a week both on FM and SSB. I never need a pre amp and though it works fine I leave it off.
     
    W1BR and KX0Z like this.
  7. N8FVJ

    N8FVJ Ham Member QRZ Page

    Brick amps likely ok using low duty SSB. But using full power out on FM I definitely would use a cooling fan on top of the heat sink.
     
  8. WA8UEG

    WA8UEG XML Subscriber QRZ Page

    I use a super quiet one used for cooling High powered LED recessed down lights. It runs on 12v and keeps the amp even at full power on FM very very cool big plus being you can’t hear it.
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    TE Systems amps are solid designs and locally manufactured (they're in L.A.); I don't like the little relays they use, but then almost everybody uses the same ones.

    I understand "service" from TES, if you have to ship it back for some reason, is terrible -- Dave is evidently always busy and items returned for service can sit for a month or more. Locally we just "drive it over" and don't ship anything, providing the opportunity to sit there and make faces while waiting.:p
     
  10. KM1H

    KM1H Ham Member QRZ Page


    Ive owned many brands and repaired most when replacement transistors were still available at a fair price. These days many of the old models are throwaways unless someone knows how to adapt new devices.

    Never had a failure here on SSB/CW even in a heavy single op or multi multi contest environment, no fan needed. OTOH I dont use FM except on occasional simplex contests and non contesting and that is with a dedicated Kenwood TM-941A and ancient Clegg FM-76 (actually a Midland) for 220 and later 222.

    Commercial repeater SS amps use massive heat sinks plus fans as far back as I can remember. The only failures were due to lack of cleaning anything and when I went to service the fins and fans were clogged with anything and everything including mouse nests.

    Carl
     

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