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Inside an old Pride DX-300

Discussion in 'Amplifiers' started by Moleculo, Nov 13, 2008.

  1. Moleculo

    Moleculo Administrator
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    One of the forum members asked me to open up my Pride DX 300, take a few pics and post them. I only took pictures of the RF deck as the power supply below would have been a bit of trouble to get to. Here are the pics:


     

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    murdog likes this.

  2. Moleculo

    Moleculo Administrator
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    One more pic:
     

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  3. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    What kind of numbers do yu see out of that amp Mole? It looks like a 4CX250B tube in it. I have a couple used 4CX250B's and sockets as well as a pair of brand new 4CX250B's and have been thinking about making an amp.Then again I have been thinking about making a few differant amps but it never seems to get past the thinking stage. :headbang The 4CX250B seems like such a waste to put on HF however when it will work sooooo good on 6m,or 2m. :drool: Maybe I need more thought. :D
     
  4. Moleculo

    Moleculo Administrator
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    It's actually a 4cx300 tube. The Pride dx-300 originally came with a 4cx250. I'm not sure what you have to do to the amp to make it handle the 4cx300...it was already done and working when I got it. It'll put out 600+ watts without too much difficulty, although this tube seems to have so much that gain you have to be careful how hard you drive it.

    Yeah, I wouldn't mind having a 2m amp with a 4cx250 for 2m...that would be excellent :)
     
  5. Moleculo

    Moleculo Administrator
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    You don't really need an amp. You should go ahead and build it for 2m then send it to me :) :) :)
     
  6. Master Chief

    Master Chief Guest

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    I have two Pride DX-300 amps. One was destroyed by Fedex (but repairable) and the other is still at Nomad Radio. He added the HV board and installed his new prototype low voltage board. The band switch, input tuning, and preamp have been removed and is now used to adjust the bias via the front panel. There is a switch installed on the back so I can switch between the 4CX250B or the 8930. The 8930 is a worth while upgrade to this amp.

    http://www.g8wrb.org/data/Eimac/8930.pdf

    Once I get it back, I'll strip it down and redo the case with powder coating and a new custom designed silk screen face.
     
  7. straight razor

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    hmmmmmmmmmm nice amp i have one thats been heavely modded, seprate power
    suppys recterfiers been beefed up with nomad boards, transformer stepped up to
    2200 hv/ 2 amps, fillment transformer is about 6.3 v 6a, 550, 150 ma, big copper polished
    coils five turns, bias's knobs in the front, 40 amp open frame relay 2 8930's dead key
    1500 bird watts., when i zero the bias knob it dead keys 40 watts and swing to 3500 pep. coax that feeds the meters to the pt load then to the relays be changed the LMR flex rg8 . direct to the meter then the relays.. no punch down pins, when i get a chance i will post the pic of this bad a@!@#$z amp on a ground plane i can keep most basestations off of me when i key on one 27.025 the super bowl and trust me when i tell you i get my name called so much i gotta go 10-7 from the dry mouth, i got a long key down oh i for got the blower fan beens changes since the back part of the amp the bottom of the cabinet is the aip champer the blower the came with the amp does not produce enuff CMF's to keep one tube cool, and i have 2, so i added a 127 CMF blower and use some plexi glass to make the champer smaller in cubic in" so that tubes would get cooler and now i can hold the key down for about lets see the last time i was talking to missippi i had it down for 2mins keying on a mudduck trying to get long winded and i kept him from being heard in missippi, for 2 mins with a 20 dbi on the meter. so with those modds u can to also have a hard to kill monster amp.. i did most of the modds but the tech that redone the box before i modded is in GA, so i call it a georgia jack ass / 82 slapper.. so master tech can u tell me how to make silk screening so i can change my face on the amp
     
  8. underdogg456

    underdogg456 Member

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    Can someone help me and my pride dx 300 my rf meter does not work and the screen light either but with my other watt meter inline im getting 300+ outta it just not sure whats wrong please help I love this amp.......
     
  9. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    Pride DX300 Manual

    Anything you may want to know about the old pride.
     
  10. Sonar

    Sonar Well-Known Member

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    I know this post is very old. I also know you're still around (my friend.) Question. I've seen many photos of the DX 300. Where are the HV caps on these amps? Are they tucked away somewhere waffered between the chassis? Or am I missing something? Thanks my friend.
     
  11. nomadradio

    nomadradio Analog Retentive

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    Here's a "before" pic showing the original two HV rectifier/filter boards on the left.

    [​IMG]

    The HV power supply is a full-wave bridge circuit. Each of the four "diodes" is in fact a series string of five rectifiers. Half the rectifiers are on each board. The six 450-Volt filter caps in series are also split between the two boards, three on each one.

    The upgrade board we sell has all that stuff on a single pc board.

    73
     
    Shadetree Mechanic and Sonar like this.
  12. Sonar

    Sonar Well-Known Member

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    Thanks for the explanation.
    While I have your attention I always wondered why you stopped accepting work that needed to be shipped to you?
     
  13. nomadradio

    nomadradio Analog Retentive

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    Why we don't solicit shipped-in work?

    Three basic reasons.

    Space.

    Labor.

    Money.

    We have been in this building for nearly 38 years. Shipped-in work requires room for the empty shipping containers, for the work that's not been finished, and for the finished work that hasn't yet been paid for. If I were to shovel out all the stuff I really should not be keeping here there still wouldn't be room for the shipping/packing/waiting-to-get-paid work. And there's not much chance I'll move out of a building that's paid for. Taking out a mortgage to expand an electronic-service business probably wouldn't look like sound business judgement to the average mortgage banker.

    The skills I need for this kind of work are obsolete. Anyone old enough to have those skills is either in the ground, in a care home, can't hold his hands steady or just can't see well enough any more.

    Okay, so that's an exaggeration. But you get the picture. The hired help I can obtain is what determines the length of our work backlog. Good help is hard to find. And training new help from scratch would become my full-time job If I tried to expand.

    But only if I could afford to. And that's where the rubber meets the road. Staying in business for this long requires some restraint in borrowing money for expansion. Soon as you do that, you have to make payments.

    On time.

    If your expansion was a good gamble, the money to make those payments comes in the door. But if it doesn't, you'll be closed before long. Banks are famous for having only so much patience.

    I won't get started on the whole issue of what they call "open bank credit". But I consider it too risky.

    The one thing I don't publicize is the work we do for other shops. There are fewer and fewer of them left. Biggest money-wasting headache from having repairs shipped to you is damage in transit. Most people have no idea how to protect electronic devices when they pack one up to ship. The labor to unpack, document the damage, and repack it for the shipper to pick up goes unpaid. Can't afford much of that. But a pro who knows how to pack a Pride is welcome to send one here for work. I should put up a post showing how to do it, probably. Naturally this is not something I publicize widely.

    But there's the "bad news" angle to consider. The total cost to ship an item here, pay me to itemize the estimate, repack and ship it back because the estimated amount was declined can easily exceed a hundred bucks.

    For just bad news. Admittedly, we itemize the bad news when an estimate is judged too high to be worth repairing by the customer.

    But yeah, if I had mo' money and mo' space, I would still need more trained help to get it all done.

    Not as easy as it sounds.

    73
     
  14. Sonar

    Sonar Well-Known Member

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    The proverbial In nut shell answer. I totally agree and understand all the concerns. I know what a losing proposition is when explained with such detail.
    Are there any exceptions to the rule? I guess the question should actually be would there be a situation in which you might or consider bending the rule, and allow someone to ship you an item? Thanks again nomadd. 73' I ask questions because the answers I get from you and other members help me to decide whether an item is worth having repaired or just putting it into the closet and accepting the fact that it is now a paperweight. No matter how detailed an answer and how exacting a repair reply is I would not be able to perform in this lifetime. Maybe in the next life. LOL 73 s
     
    #14 Sonar, Feb 18, 2018
    Last edited: Feb 18, 2018
  15. Two Pack

    Two Pack Active Member

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    I want to thank everyone in this thread for the pictures and info!

    I recently acquired a Pride DX300, nut it's missing all the boards!! It currently has a 4cx350a tube in it. Hopefully I can get that to work! Ive been after it for a while and I finally talked him into taking my lunch money for it!

    I'll have to get a hold of nomad radio in the next few months for some boards.

    I'm new to working with tubes so I'm taking my time, researching and learning CAREFULLY! I don't want to blow up myself or the amp!

    20180603_111551.jpg 20180603_111527.jpg
     

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