RFX75/Mosfet finals/Stinger Board

Discussion in 'CB Radio Forum' started by deerslayer1143, Mar 27, 2011.

  1. deerslayer1143

    deerslayer1143 Light Load Member

    207
    19
    Mar 15, 2011
    Dubuque, IA
    0
    Handlebar...I'm installing an RFX75 on a cobra 25 ltd classic that I got working. The RF IN coax center conductor goes in the front hole of R40 that was removed. The RF IN shield is to be soldered to DC ground. Just trying to figure out the best place to do that given the length of it and my question of where exactly on the board does DC ground exist. Where on the board is DC ground? The only sure DC ground I know of is the back of the power connector. Actually the shields for both RX OUT and RF IN both need to go to DC ground.
    RF OUT shield goes to chassis ground on the antenna connector with the center conductor going to antenna connector's center pin.

    Those 2 coax shields going to DC ground are all that's holding me up. I want to make sure I get it right being my first RFX75 install.

    The radio in my sig is my new radio I just purchased and arrived today. I had the RFX75 installed on it before it shipped. The 25 is a radio that was dead that someone gave me. I got it working and am installing the RFX75 on it myself to sell to a friend cheap since he doesn't have much money. Basically the cost of the RFX75 and shipping it. He gets a nice little radio that will put out nicely and I gain a little knowledge. A win/win situation so long as it works. lol

    Any help would be greatly appreciated and thanks in advance sir handlebar.
     
    Last edited: Apr 2, 2011
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. deerslayer1143

    deerslayer1143 Light Load Member

    207
    19
    Mar 15, 2011
    Dubuque, IA
    0
    Nevermind. She's a done deal. First one is always the hardest. Especially with the vague instructions.
     
  4. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

    7,309
    14,655
    Jan 20, 2010
    Hesperia, Ca.
    0
    BTW, where did you buy RFX75 and how much ? I have a Galaxy 44 I might want to experiment with it. It's my back up radio and I use it in my 4 wheeler. I already have it in my other radio but I had them put it in.
     
  5. deerslayer1143

    deerslayer1143 Light Load Member

    207
    19
    Mar 15, 2011
    Dubuque, IA
    0
    I got mine on ebay cuz all the shops were out of stock. Paid $44. You can get them for $39 somewhere that slips my mind atm but they were sold out. I'll get back to you if I can find out where that was and if they have any back in stock. I get the feeling they are pretty popular and sell out fast. One shop quit selling them for this reason. Don't remember which one that was either.
    You won't see quite the swing in a galaxy as you do in the cobras but I would guess it would be enough to still make it worth the approximate 40 bucks not to mention the learning experience.

    For me it came down to not wanting to go without my radio should I ever want to have work done and ship it half way across the country to a faceless name I don't know and wait for weeks. So I decided to start learning and buy the necessary equipment to do the basics and go from there. My wife works at a truck stop just outside Dubuque that has a new owner that's sticking a lot of money into the place and it would be a great place to work out of or at least use as a drop off pick up point. There is no one anywhere near here that does this kind of thing and I enjoy it so why not give it a try. A lot of truckers I talk to say the same thing. I'm not looking to quit my day job but maybe a nice little secondary business is in the cards down the road. Time will tell.
     
    Last edited: Apr 3, 2011
    Diesel Dave Thanks this.
  6. deerslayer1143

    deerslayer1143 Light Load Member

    207
    19
    Mar 15, 2011
    Dubuque, IA
    0
    If you want to pay the shipping I'd be happy to do it for 20 bucks plus the RFX75.
     
  7. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

    7,309
    14,655
    Jan 20, 2010
    Hesperia, Ca.
    0
    I was just checking out ebay and they want 109.99 for the RFX75 !!!! I paid 100.00 at the cb store and had it install and tune my main radio all for 100.00.
     
  8. deerslayer1143

    deerslayer1143 Light Load Member

    207
    19
    Mar 15, 2011
    Dubuque, IA
    0
    Oh wow! Sounds like they are realizing the shortage and jacked up the price. That sucks. Glad I got the one I did when I did. Anyone plays that game, cb shops included, I will never buy from them again.
    I paid 85 installed and tuned on my new 29.
    The good thing about hooking up with the owner of the truck stop my wife works at is I will be able to get anything I need wholesale by having him order it!
     
  9. handlebar

    handlebar Heavy Load Member

    Sorry I took so long to get back; I'm in Iceland doing the tourist thing after attending an Eve Online Fanfest here, and internet service is ironically hit-and-miss here.

    It looks like you already got this solved, but in case others are wondering, here's a link to a great resource, with the specific model of radio you're working with:

    http://www.cbtricks.com/miscellaneo..._75/graphics/rfx75_install_guide_cobra_25.pdf

    The DC ground is pretty much any of the largest "land mass" on the foil side of the board, and can be confirmed with no power applied to the board. An ohmmeter from the negative power lead to the biggest foil area(s) should show zero resistance with the meter leads in both positions, i.e., red to plug and black to board, and vice versa.

    Best engineering practice dictates keeping all RF leads as short as possible, so presumably you grounded the shield adjacent to where the coax center leads went. This helps prevent stray RF running around in places where it oughtn't.

    HTH, even if it's late. BTW, did you have decent receive sensitivity after your install? A lot of folks have ended up with numb receivers after putting on the RFX units on their Cobra 25s.

    -- Handlebar --
     
    Yup Thanks this.
  10. Yup

    Yup Medium Load Member

    569
    129
    Apr 2, 2011
    Everywhere,USA(Texas)
    0
    Cobra's already suck on receive,the RFX doesnt help matters,but
    its still a very wicked set-up for the invested coin.
     
  11. deerslayer1143

    deerslayer1143 Light Load Member

    207
    19
    Mar 15, 2011
    Dubuque, IA
    0
    Actually I'm having bigger problems and I think it has to do with what you said about 25s DC ground being chassis ground with all those capacitors. I'm not getting any receive or transmit. just squelch noise and no needle movement. Maybe I went astray somewhere or maybe the dead radio I revived just died again. lol Not quite sure at this point.
    Open to suggestions at this point but I'm stepping back from it right now unless someone has something worth looking at. Maybe just a bad solder.
    Thinking about taking the RFX75 off and putting it on a uniden pc68 that I know has no problems in the first place.
    Would soldering those 2 coax shields directly to the dc ground on the back of the power plug in where the black ground wire goes be an option?
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.