Under-performance of EP-AB003 WiFi amplifier

  • Hello all,

    My EP-AB003 "8W" amplifier works but only has 11.5dB gain as opposed to the claimed 17dB so I get +29.1dBm out for +17.6dBm in. At the moment I don't have more drive available to see if I get more power output for more input. Lack of output power seems to be a common but not universal complaint about these units.

    Anyway, I took the lid off and have noticed that there are some suspicious white blobs of what looks like foam on some pins of the device associated with the output combining and also two pins may have a solder bridge:

    Is the white stuff just flux residue or were those areas not actually soldered? I assume(!) that the white blobs at the two corners of the device are not actually pins so only the middle left hand side blob is important. I'm going to need to buy a much finer soldering iron, steadier hands and better eyesight if this needs reworking :(

    Does anyone know what the device is? I searched on the "2031 1RNT" but couldn't find anything relevant.

    73 Chris

  • Hello Chris,

    Your image is showing the OUTPUT site of the device.

    The "part" of interest switches between the RX and the TX-branche of the PA. If you want to use the PA only for TX (e.g. QO-100) then you can just bridge the part and get about one additional dB :-).

    If you also need to RX via the PA this modifiaction is not suitable for you.

    The "wire" goes from the marked PIN to the marked solder joint of the capacitor (not to the pin of the IC - the image is not very good thus someone could be miss leaded - so I repeat: solder to the marked point of the capacitor !!).

    73 de Johannes

  • That's about an average gain for those amplifiers. There is nothing wrong with it I'm afraid.

    As mentioned by Johannes above, you can bridge the input and output switches to get a dB and a bit more gain.

    Most people run them with closer to 23dBm in to get full output. These amps get a bit of a bad press for splatter, but in reality they will run pretty cleanly up to 3W out - the difficulty is that people are using preamps with a P1db of 20dBm as those are the only easily available ones from ebay etc.

  • Thanks Johannes and Richard,

    The chap who wrote the Radcom article must have been lucky then because he measured 16dB of gain with +30dBm output.

    As I only require TX I might try the link modification.

    73 Chris

  • I guess they may vary - but I have two and they measured 11.6dB and 12.4dB at around 2W out.

    The articles and postings I've read tend to agree with this - 12dB is the most common reported and the highest I've seen was 14dB, but that was with the supply mod and I think the link mods too.

    I have a 4W model which gave a bit more gain, but less output.

  • G4SDG Hi Chris.
    I have the same gain as you, just a little over 12dB, but have between 2.5W and 3W output when driven from 170mW. - comfortable level for SSB with a 0.8m dish.
    I think the 'gain' quoted on the seller's websites includes the gain of the antenna !

    At 3W the output is clean but my driver is a BU500 converter which uses this PA chip.

    RFPA5208 Data - Qorvo

    73 David

  • I got around to measuring the unit today and mine has around 11dB gain. Saturated output power is 35.3dBm (3.4W). Output did look reasonable at 3W driven by my SG Labs transverter.

    Now to work out why my 1980's vintage SSB Electronics transverter is only producing 18dBm which is a bit light to act as a driver.

    I've not found any other "cheap" WiFi boosters and will probably just stick with this one, but perhaps bypass the output switch and place the unit at the antenna. I've got two Spectrian modules but have other plans for those!

    73 Chris

  • given that the 4W boosters sell for 20 USD, using one as a driver stage for any 8W booster is probably easiest.. and if driven so far away from its limit, it will be linear enough for sure.

  • DD1EG

    Hello Detlef,

    more than 12V is only more stress for the internal DC-DC-transformer of the PA. The applied 12V are internaly regulated to 6V.

    Thus if you really think about higher voltage:

    First look at the datasheet of the power transistor - especially the voltage specification. And if there is enough headroom, then you have to change the internal DC-DC-converter or inject the higher voltage direct.

    But I think HB9SKA is right....nobody will recongnice a difference between 3,8W and 4,3W ;-) So it's not worth the effort.

    73 de Johannes

  • During QSO's I observe my signal on the Goonhilly WebSDR. If I send a long duration CW-signal it drops down after a short while. I think because of overheating. After a break the signal is OK again. In SSB I have no problems with this booster. But I think for digital modes this booster is not suitable with small dishes.