2 Meter & 450mHz Brick Amplifiers- Short take

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

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    100 watt to 160 watt solid-state or called 'brick' amplifiers are expensive new, so it makes sense to buy used. But, all are not equal in performance. I perform a lot of research and will not blindly buy anything. eHam reviews are a good resource for amplifier performance. So, what are the best amps and what should you avoid?

    Stay away from Mirage amplifiers. These are noted to have issues and failures. Most do not have a good high SWR protection circuit either. The best amps are made by TE systems & RF Concepts. The KLM are also good, but many lack the handy receive preamp. I recommend TE Systems and RF Concepts.
     
  2. KM3F

    KM3F Ham Member QRZ Page

    I use a Mirage 2518G that has good SWR protection and improve bias source and stability.
    With fan cooling and 15 volts it outputs nearly 200 watts with 33 watts drive on FM.
    As the supply voltage goes up the SWR protection circuit trip goes up with it.
    Been running it this way for several years.
    Don't be alarmed at running it at 15 volts. The device is made for the upper voltage limit at 18 volts.
    The designer specs 13.8 as normal with a safety margin and to go along with others as 13.8 is not the limit.
    If it were used in mobile, it could see 15 volts at times.
    Good luck.
     
  3. N8FVJ

    N8FVJ Ham Member QRZ Page

    Mirage B5016G only rated a 2.8 out of 5 on eham reviews with 2 pages of comments. 4 and above ratings are considered good products.
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Biggest problem with that amp and most all the SS "brick" amps no matter who made them is "cooling" issues.

    The Mirage 160W and higher power amps really, really need a cooling fan blowing across the heatsink in an effective manner. That simple addition which might cost $10-$12 can greatly extend operating life, especially when used for FM. On SSB they don't get nearly as hot, even with continuous transmission.

    The RM Italy LA250V 2m amp is actually superior to the other brands currently offered. I've tested it repeatedly: Very "straight line" linear up to ~150W output, hits 1 dB compression at around 200W (but so do all of them, and the bipolar amps are worse), and effectively cooled by two fans built into the heatsink like this:

    [​IMG]

    It is FCC certificated for sale in the U.S. It has a simple RCA phono plug for keying. Uses four Mitsubishi 70W power FETs with a combiner, so with ~45A supplied could run as much as 280W output pretty safely, but the design restricts it to 200W and above that it will self-protect.

    Pretty slick design...but not cheap!
     
    KW6LA likes this.
  5. K6CLS

    K6CLS Ham Member QRZ Page

    Would be great if some 222MHz brick amps were in production by someone...
     
    KD8TUT likes this.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    TE Systems in Los Angeles makes 222 MHz SS "brick" amps from 35W to 500W output...

    http://www.tesystems.com/222-225.htm
     
  7. K6CLS

    K6CLS Ham Member QRZ Page

    Yeah, those are good

    I haven't decided whether to spring for one, or build a W6PQL
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The TE amps are pretty good -- but if possible, avoid the built-in preamp. That circuitry adds more internal relays which are absolutely guaranteed to fail, and when the relays fail (high contact resistance -- they don't actually "burn out" or anything) although they're inexpensive, they're a real pain to replace.

    I never use the preamps in any of these bricks.
     
  9. AA7QQ

    AA7QQ Ham Member QRZ Page

    I have a TE repeater amp. 19" rack mounted heat sink. No fan needed.
    Ed
     
  10. KM3F

    KM3F Ham Member QRZ Page

    99% of the time a built in pre amp is a sales incentive. They don't help at all but raise the noise level.
    For 222 band I could not find a new or used amplifier unless it was a new TE that you have to order because they apparently only build when an order is placed. The cost was too high to justify.
    I was about to build one using a pair of 4cx250 having all the parts when a source of 220 amps was found stored and at give-away prices for the amp and matching power supply.
    This equipment was part of a failed business system tried in the northwest and all removed.
    Found the schematic and other info on the internet that was enough to see what the working deal was.
    It appeared complicated to most so they were never sold.
    Easy to figure out if your amplifier savvy.
    The gain of these amps is --get this--- 40 db. Therefore attenuation has to be used in nearly any application such as a Transverter to control drive power. The amplifier was direct driven from a receiver hence the high gain requirement.
    The amp runs on 26 volts, is built like Swiss Watch, British designed back in the late 90's.
    I built the system up in 2015, contested with it, drive a pair of beams at 190 watts on FM,
    Have power control 15 to 190 watts using my adjustable attenuator controller.
    If the amp ever goes I may not be able to repair if any of the surface mount components ever need replacing. This amp is built way beyond amateur standards.
    So far there are no 222 stations on for SSB unless contesting and only ones that have SSB capability, a few on FM but there are many repeaters out there setting in silence in the northeast.
    Do what it takes but get on the band, it's nice.
    Good luck.
     

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