1. Marconi is the winner of the December WDX CB Club DX Contest! Please Congratulate him here!

Galaxy DX2517 extremely low power

Discussion in 'CB and Export Equipment and Accessories' started by Highlander_821, Mar 28, 2010.

  1. Highlander_821

    Highlander_821 Amour d'Ecosse

    Joined:
    Apr 2, 2005
    Messages:
    1,068
    Likes Received:
    14
    My Galaxy DX2517 has developed a problem on TX. I can get the radio to key on AM, FM, and SSB modes, but only a very, very tiny amount of power results.

    Not even the slightest indication on a 5 watt scale meter. The radio indicates that it is modulating, and it can be monitored on another radio ( I can hear the audio). I was running SSTV when it happened, or just before it happened.

    Ater testing SSTV transmit and receive, I disconnected everything to try to neaten up the wiring and all, and when I got everything buttoned back up, I went to transmit SSB voice with my mic and discovered that all of a sudden I have almost no power!



    Any ideas? I wonder if I put too much audio from the soundcard into the microphone circuit... Could that possibly start a chain of events that could lead to this failure?

    Thanks for any thoughts or advice at this point.
     
    #1

  2. Highlander_821

    Highlander_821 Amour d'Ecosse

    Joined:
    Apr 2, 2005
    Messages:
    1,068
    Likes Received:
    14
    Ooops! sorry for the double post! :redface:
     
    #2
  3. pro151

    pro151 KB4RMA

    Joined:
    Nov 10, 2007
    Messages:
    1,986
    Likes Received:
    223
    Your fired! Turn in your mouse and clean out your locker. :D
     
    #3
  4. liquidh8

    liquidh8 Active Member

    Joined:
    Aug 7, 2011
    Messages:
    271
    Likes Received:
    4
    I have a saturn that just started doing this.
     
    #4
  5. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    8,287
    Likes Received:
    1,056
    Check the bias settings on the finals. Either those bias diodes are gone and it won't bias; or the final transistors are gone. If it was a modulation problem; then AM still should show proper dead key power. From what you have said - it doesn't. The reason you still see some power out, is probably because the driver transistor is still working.

    http://www.cbtricks.com/radios/galaxy/dx2517/dx2517_trans_adj.htm

    http://www.cbtricks.com/cgi-bin/database/galaxy_db.cgi
     
    #5
  6. 9C1Driver

    9C1Driver Well-Known Member

    Joined:
    Aug 13, 2008
    Messages:
    2,384
    Likes Received:
    432
    Were you running SSTV as well?
     
    #6
  7. liquidh8

    liquidh8 Active Member

    Joined:
    Aug 7, 2011
    Messages:
    271
    Likes Received:
    4
    Thanks for the links. Ill have to get it to do it first. I can talk on it for a while and all is good, then all of a sudden, nothing. After I turn it off and it cools down, then it is good again. the driver and finals are new from a few months ago.
     
    #7
  8. jazzsinger

    jazzsinger Bullshit Buster

    Joined:
    Jul 3, 2008
    Messages:
    1,726
    Likes Received:
    265
    that's very possible and most probable, but also possible is a missing/low tx mixer signal, could be the low output isn't even on 27 mhz, (very hard for a tuned output stage to amplify an out of band signal as efficiently as an inband one) power meters ain't smart enough to tell, but a frequency counter inline with it might,

    this was actually seen by a friend on a magnum 257 that had both driver and final working but still low output, no reason it couldn't happen on any other uniden clone. caused a few people a lot of head scratching, always worth checking the oscillator signals are present, before you assume the rf amp is fooged.

    time to get a scope and freq counter out.
     
    #8
  9. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    8,287
    Likes Received:
    1,056
    All verry true. And yes, it was a rush to judgement as to the problem. However, we also know that a lot more radio output failures are most often the finals due to a poor SWR or just plain over-driving them until they fail. That seems to be part of the original post, ergo my reason for the finals diagnosis.

    But it could be a plethora of things that can give these syptoms as we know. Since one poster said, that if he turns off and leaves the radio alone for awhile, that it is OK once again. Well in that case, I would suspect either a simple cold solder joint or a part that becomes intermittent after a certain temperature has been reached (thermally compromised).
     
    #9
  10. liquidh8

    liquidh8 Active Member

    Joined:
    Aug 7, 2011
    Messages:
    271
    Likes Received:
    4
    good replies, thanks guys. It helps keep it all in one thread also. As for me, today I changed the Am regulator to the 817 (i had 4 laying around). Talked on it a good bit, and it has been running for a few hours now. So, I'l see what happens. I had a hard time checking it, as the last time it did it, I tool the covers off, got the meters off, and it started working. I did manage to check the final and drivel bias, they were still good. The voltages to the driver and finals, and the bias voltage were good. By the time I got to the regulator, it cooled off and started working again.
     
    #10
  11. jazzsinger

    jazzsinger Bullshit Buster

    Joined:
    Jul 3, 2008
    Messages:
    1,726
    Likes Received:
    265

    a simple way is to test the regulator output voltage when the power drops but the best way imo to determine a thermally intermittent semi conductor is to blast it with freeze spray while its hot and see if power is restored, if so you know its on its last legs, many transistors/ic's show this type of weakness before complete failure and can be a demon to find.

    using the freeze spray allows you to test a few components you may suspect much faster whilst the radio is still on.

    regulators are common failures on most pb010 clone chassis especially those with tweaked power, on early pb010 radio's the failure rate was huge with so many people screwing the power up, that extra power comes at the cost of spectral purity AND component longevity, it just ain't worth a couple of extra watts that no-one (apart from you staring at a power meter) will ever notice anyway.

    later pb010 single final (1969/2312) clones came with upgraded regulators as standard but that just caused more blown outputs as the final wasn't upgraded for the higher power levels sellers would tweak their radios too, so they could sell them in competition with the president range of radios using mrf 477's for double output, the dual final (1969/2312) clones should be ok with the higher power and upgraded regulators as long as you don't try to draw stupid amounts of watts from them,(8w am/fm 20w pep is about right on those).

    when enquiring about faults in a radio, its always best to state the board number and if its bi polar or mosfet outputs, most export radios in the past 10 years or so have had many upgrades as original parts became scarce or no longer made. even snippets of info you might not think relevant can help people narrow the causes down, especially if they are familiar with your particular board/regulator/output setup.

    hope you get it going, its a lovely looking radio, just a pity when cybernet originally designed those type of base stations they put shitty cybernet boards in them and not uniden boards or the uniden clone boards you find in modern versions. come to that its a pity uniden at the time didn't learn from cybernet and put one of their top pb010,pc999 or pb042 export boards inside a cobra 2000 gtl chassis (arguably the best looking cb ever made). they'd have made a killing, just like ranger have since on them.
     
    #11

Share This Page

Members Online Now

  1. undertaker,
  2. teaman440,
  3. fonman,
  4. bob85,
  5. vkrules,
  6. 025,
  7. 26sd782,
  8. BJB,
  9. Robb
Total: 243 (members: 10, guests: 152, robots: 81)