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Rocketbox info thread !!! Made in the USA with a reasonable pricetag !

Discussion in 'Amplifiers' started by WINKDOGG, Nov 30, 2019.

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Would you like to build you own Rocketbox linear from a kit ??

  1. Hell yeah !

    51.2%
  2. No thanks I can wait and pay extra for Rockets assembly time.

    16.3%
  3. More Junk! NO THANKS!

    32.6%
Multiple votes are allowed.
  1. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    FROM FB INFO:
    Rocket 1000XL 2x8 low drive 3-5 watt dead key 40 pep max input for full output. 750-875 watts pep. This unit is AB1 biased, (?) it's super clean on AM and SSB. There is no other amp like it. We have spent months making this unit 100% satisfactory. This unit is 5X15" for cool running
    We are doing a promotion to ease wait times for production before we add them to our website. We have a 60 day wait time max to be safe to cover all other orders as of now because of COV19. Also each Rocketbox unit comes with a 60 day warranty on all parts and house except transistors. But if ran CORRECTLY you will never have issues with them. To order please PayPal to rocketboxelectronics@outlook.com if you don't have PayPal you can pay with CC
    and add your phone number, email, and address. Also we have black, blue, red, gold face plates Thanks Rocket

    1 Unit: $739.00 each+ 34.99 shipping

    60 Day lead time!


     
    Cam Tetzlaff and AudioShockwav like this.

  2. blasphemy000

    blasphemy000 Active Member

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    There appears to be small SMD inductors beside each output transformer. I can't tell from the image if they are feeding power to the transformers or if they are for some other purpose. If they are, they seem a bit small for the job, I would think. On the other hand, Ranger uses 2 of those small inductors in series to feed DC to each output transformer in my 63FFC4 radio and it has 2SC2879s in it. I'm sure there is voltage drop across them though due to the small conductor size. I think some ferrites slipped over the power conductors before they get to the PCB would be beneficial as well.
     
    AudioShockwav and Shockwave like this.
  3. Eldorado828

    Eldorado828 8-2-8 in the Lonestar State

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    I think I'll let time prove them solid before I'd drop that kind of coin.
     
  4. Shockwave

    Shockwave Sr. Member

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    It is likely that in the case of the radio, there are additional RF chokes between the PA board and the power cord. I did however, miss the small chokes you mention here. Thanks for pointing them out. As you say, they are small for the job and it's not just the DC resistance causing voltage drop. It's the lack of enough impedance at RF to block the amount of RF present in this location. One pass through a bead this size, does not offer an ideal place to drop unwanted RF.
     
    #169 Shockwave, Sep 6, 2020
    Last edited: Sep 6, 2020
  5. Shockwave

    Shockwave Sr. Member

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    I noticed C14, the input padding cap to the 8 transistor section, has been removed. That suggests that the input impedance to this stage, is below 50 ohms and cannot be "dialed in" by adding any capacitance. To confirm this theory, look at the turns ratio used on the RF transformers. They are the same for the driver stage as they are in the final. In fact, it seems every Rocket box regardless of size, uses the same turns ratio in every stage.

    Assuming the driver is at 50 ohms, using the same turns ratio with 4 of the same stages combined, results in a 12.5 ohm impedance. While I can't read the value of the other padding caps used here, they should not be the only change made to compensate for this much of a difference in impedance. That could also be the reason we see little more than 12db of overall gain, including the driver stage.
     
    #170 Shockwave, Sep 6, 2020
    Last edited: Sep 6, 2020
  6. blasphemy000

    blasphemy000 Active Member

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    Oddly enough, on my Ranger's PA board, each output transformer only has the 2 series ferrites between the transformer's center tap and the main DC bus traces. There are some 100n caps to ground directly on the bus side of the ferrites, but I'm sure it's not ideal.
    Also, the ferrites in my Ranger don't appear to be a simple single pass bead. They look to have a flat ribbon type conductor inside with a couple of turns, but hard to be 100% certain. I have found identical looking ones online before that come in different inductance values, so it's a possibility. Without breaking one open though, I don't think there's any way to know for sure.
    With the points that have been raised, I would be curious to see one of these put through it's paces in a lab setting with all the proper test equipment and such.
     
  7. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Has anyone tried one of these amps?
     
  8. Eldorado828

    Eldorado828 8-2-8 in the Lonestar State

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    A few years ago (Right before hurricane Harvey) I tried the 250 MOS. A guy named Justin owned rocket box then and I purchased one for 100 bucks. He was just getting going so he made me a deal. Story was that he bought it from a guy in Houston that made the Palomar LD/HD amps. Anyway, back to the topic. I had it a few months, it worked in the real world of a truck but used it only on AM. That's been a while so it may not be the same animal sold today but I did own one. I'm not even sure if it's the same fella that owns and builds them now.
     
    443, Shadetree Mechanic and Slowmover like this.
  9. 443

    443 W9WDX Amateur Radio Club Member

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    Yep. I know Justin, and the guy from Houston that built the Palomar amps (in this area Houston anyway, there are many other Palomar builders), I have been out of touch with him for a while, hope he is doing ok. I had the old 250Fet and 450Fet circa 2010-2011. Sold a couple to some friends too. They did work, just I have a problem with the extremely low gain of the ERF 7530 devices. Kinda pointless waste of a bunch of circuit board and transformers. I am not against experimentation AT ALL, I am glad people do it. For 12V though, I think everyone should just support MA/COM and use MRF454's. I do hear that HG Semi is coming along with their 2879 replacements though, taking them long enough...
     
    Slowmover and Tokin like this.

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