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Looking for info on Palomar MOSFET Amp

Discussion in 'Amplifiers' started by loopy, May 24, 2010.

  1. loopy

    loopy Member

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    Hi guys.. new here. Been reading and learning heaps here lately.

    On the lookout for an AB amp, I recently came across an ad for a Palomar FET250 Class AB1 Amp. From my understanding, Palomar was a company from way back, and the Palomar name is being carried on by some other mob. But I digress.



    Going by their description, this thing is powered by 2 x MOSFET ERF 7520 Transistors.

    Doing a search for ERF 7520 (and IRF 7520) specs returned no results. Anyone heard of these MOSFETs or know anything about them? Thanks.
     
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  2. GLR

    GLR Keeping It Good Natured

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    #2
  3. mackmobile43

    mackmobile43 Jock Supporter

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    Mack chuckles, isn't this the same as not selling an export radio without the jumpers inside that designate what frequency it will operate on? I'm sure that's how uncle charlie sees it and I'm sure some well meaning amateur informant will act on.


    [FONT=Arial, Helvetica, sans-serif]IMPORTANT NOTE: So as to comply with eBay regulations, this amp in its current state is NOT designed to transmit on 24 mHZ to 35 mHZ frequencies which is deemed against eBay selling policies. In its current state, it does NOT contain SO239 / PL259 connections so it CANNOT plug into any ham or cb radios. This amp has multiple uses. After the purchase of this amp has been made, customer must email or call and request the amp be designed to work with their ham radio if desired. Please understand, we want to comply with eBay regulations therefore these amps must be built to order given their multiple uses.[/FONT]
     
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  4. TonyV225

    TonyV225 Supporting Member

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    I cant believe how hard I laughed at that ad when reading it LMAO!!! That is by far the best so called legit ad Ive ever seen on EBAY. (y)
     
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  5. 9C1Driver

    9C1Driver Well-Known Member

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    Skywalker is building some nice mosfet amplifiers.
     
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  6. Lazybones1222

    Lazybones1222 W9WDX Amateur Radio Club Member

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    Compared to what?
     
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  7. loopy

    loopy Member

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    I hope not.



    I'm tempted to try one of these, but I'm just worried that should something go wrong, it'll be hard to find replacement transistors.

    I wasn't actually considering a MOSFET design, but it's got me curious to see what's out there now.
     
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  8. radioman2010

    radioman2010 Member

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    Palomar FET Amps

    These are just now being manufactured and are excellent amps, especially for SSB use.

    The transistor used in the amps is the EKL ERF 7530 100 watt FET and are easy to purchase from RF Parts.

    Very favorable reports have been received from the first buyers of these new amps.
     
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  9. mackmobile43

    mackmobile43 Jock Supporter

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    If mosfets are proned to damage from static discharges would having them connected to an antenna during a lighting storm put them at greater risk for damage?
     
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  10. Shockwave

    Shockwave Sr. Member

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    The IRF7530 is being used in these new amps because it's cheap. While the datasheet says it's designed for high power RF, the TO-218 package says otherwise. When you compare it to the case style of the 2SC2879 there are big differences. Quality RF transistors use wide connection tabs for low inductance. They have dual emitter connections to keep the emitter at absolute RF ground. The case has the junction bonded to a ceramic insulator that is bonded to it's metal mounting base requiring no external insulator. Even though the ERF7030 has a dissipation of 150 watts, all of these things contribute to it's low 20 watt RMS output rating. They may be good for replacing the finals in a CB but would be a poor choice for producing any reasonable power level.
     
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  11. 9C1Driver

    9C1Driver Well-Known Member

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    Yea, I guess I should have said Skywalker builds a nice amp, and I see he builds mosfet amplifiers now too.


    Years ago a custom amp builder would sell you an amplifier for display purpose only. To make it work you had to take the cover off and plug a connector in.
     
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  12. radioman2010

    radioman2010 Member

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    Comparing the ERF7530 to the 2SC2879 is like comparing apples to oranges.

    The FET is much better for RF use because they are much faster with less loss, thus less heat generated. The FET does not have the poor grounding and oscillations associated with bi-polar transistors which is another plus.

    The Palomar 250FET uses 2 of the ERF7530 and produces peak power of 200 watts.

    The Palomar 450FET uses 4 of the ERF7530 and produces peak power of 400 watts.

    Intial feedback reports are all excellent.

    So I don't know what you're talking about when you say the ERF7530 is good for only 20 watts ? Get a clue.

    As for the IRF7530, that transistor has nothing to do with the products being discussed.
     
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  13. SharpShooter

    SharpShooter Member

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    #13
  14. Unit 148

    Unit 148 Member

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    Can anyone tell me if there is a 900W FET mobile unit on the horizon?

    I think that would be an ideal box for a 100W ham or 11m transceiver.

    Tnx

    Unit 148
     
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  15. Robb

    Robb Yup

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    The Magnum SX-175 'Power Cabinet' uses two ERF-7530 MOSFET's. The last time I talked to Sam Lewis of RF Limited/Magnum Int'l - he said that they also have a four ERF-7530 amp in the works too.

    Wouldn't be at all surprised if they came up with a larger amp still. After all, RF Limited are the mfr of the EKL brand - that makes the ERF series of MOSFETs.
     
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: mosfet

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