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Acom 700s user opinions

Discussion in 'Amateur Radio Amplifiers' started by GW4RDW, Mar 9, 2021.

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  1. GW4RDW

    GW4RDW XML Subscriber QRZ Page

    Hi David,
    unfortunately the GU74b tubes are not readily available here in the U.K. A good friend of mine used to service and repair the Acom amplifiers for the initial importer to the U.K. He used to have a supply of tested tubes but they have all been sold. I have recently purchased a tube (NOS) from the Ukraine and they don't come with any warranty. I think the last Svetlana tubes were produced in about 1993 so wherever I buy them from in Europe they will have been on the shelf for at least 28yrs! I'm a victim of my own good fortune in that the original tube lasted for around 15yrs hi! I could kick myself for not purchasing a spare tube(s) at the time I bought the amplifier. Hindsight is a wonderful thing!
    Again my thanks to everyone who has contributed to the thread.
    Keep safe and well.
    73 de Ian GW4RDW.
  2. KD9VV

    KD9VV Ham Member QRZ Page

    Late to the dance but;

    I've had mine 2 days.
    Only ran it on 6M since my slopers for HF can't take more than 200W.

    Ran 6M AM/FM/SSB, FT8 and msk144 at 600W out.

    FM/AM obviously places strain on any amp. Temp was running close to warning zone after 2 mins key down at
    600W out. The other modes present no problems and run w/o issue.

    Fan noise does not seem objectionable to me.

    As far as SWR; my 6M will vary depending where it's pointed from 1.4 to 1.7...No problem tripping the amp.
    See no need for a expensive tuner at these swr numbers.
    1 person likes this.
  3. N3DT

    N3DT Ham Member QRZ Page

    I recently took off my extra fan from the A1000. Now it sounds about like my TS2000 when the fan comes on (all the time), which is acceptable. I still have to see the exhaust temps go above 54°C and that's running it at 1KW out 450W PD FT8 on 17M in the mornings here in the east US. Seems to be the only way to reach EU and beyond at that time although I hear J through K and even into L grid squares fine. I really can't complain about this amp for a KW.

    Ian, is it just too expensive to import a tube from DXE? There's probably a huge import fee, even if it did come from RU. I guess I'm glad I bought a spare. The more I use this amp the more I like it as opposed to the AL80B, which was OK.

    I did find an equivalent 24V fan with lower RPM and ordered it from digi-key. We'll see if it works any better (quieter), I figure the cooler the tube, the happier I am.
  4. EI2IJB

    EI2IJB Ham Member QRZ Page

    700s user here, very good amp. It uses the new finals which are a big step up v the 600s and 1200s finals.

    It uses the same ones used in 2000a.

    Mine runs very quiet. Fan almost never on in ssb. On cw it comes on but still not very loud.
    1 person likes this.

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