1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Strange problem with Uniden Washington S-meter

Discussion in 'CB and Export Equipment and Accessories' started by loosecannon, Jul 25, 2018.

  1. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    hi all.

    I'm having a bit of a strange issue with a uniden (8719) washington im working on.

    It seems that the S-meter reads differently in receive depending on which mode the radio is in.

    AM reads normal (S9 @ 100uV) but USB reads a bit higher, and LSB a bit higher than that. it's a total of about a 2 S-unit difference. (EDIT: it's the "resting state" of the S meter that is different.
    like, AM reads below S1, USB reads S1 and LSB reads just under S2)

    the clarifier has been unlocked, and the meter light has been replaced by an LED. radio is re-capped and aligned.



    right now my suspicion is that i need to remove R144 or R146 thinking that the clarifier is still connected to the 7.8mhz filter (FT1) but that is just a guess from giving the schematic a look.

    I am at work and am hoping to work on this tonight so i thought i'd bring the community in on this one since i haven't seen it before.

    ideas?
    thoughts?
    insults?
    LC
     
    #1 loosecannon, Jul 25, 2018
    Last edited: Jul 25, 2018

  2. kaos513

    kaos513 Well-Known Member

    Joined:
    Apr 10, 2014
    Messages:
    1,511
    Likes Received:
    273
    Is the radio recapped?
     
  3. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    yep.
    just got done restoring it.

    There is only one S-meter adjustment in this radio, so i am looking at the differences between being in AM mode as opposed to SSB mode.
    LC
     
    kaos513 likes this.
  4. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    well i haven't even gotten home to check it yet, but im pretty sure i know what i did.

    I believe that i used the wrong wire when doing the clarifier mod. DOH!

    Still open to any ideas, but i have a sneaking suspicion that the problem is due to a loose nut behind the soldering iron.
    LC
     
  5. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

    Joined:
    Apr 23, 2018
    Messages:
    1,159
    Likes Received:
    811
    Been there done that...

    New Techs.jpg

    Some days, those fingers are hotter than others...

    SIGH...THX Crtzlow...

    :+> Andy <+:
     
  6. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    Thanks for that pic Andy. LOL

    she's obviously very quick with that iron.

    I will post back tomorrow if it wasn't just a dumb mistake.
    LC
     
  7. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    well im bummed because i actually did the clarifier correctly LOL.
    (how could i have ever doubted myself!)

    im mostly posting this here to document what im finding, but im still open to any ideas.

    100uV input is the same on all modes (s9)

    10uV is S2 on AM, S3 on USB and S5 on LSB.



    back to work.
    LC
     
    #7 loosecannon, Jul 25, 2018
    Last edited: Jul 25, 2018
  8. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

    Joined:
    Apr 23, 2018
    Messages:
    1,159
    Likes Received:
    811
    Maybe a "carrier offset" issue?

    The AN612 is what I'm thinking...
     
  9. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    well that was a fun one.

    It was CT2. replaced and all is well.

    pretty much as soon as i posted my last post i realized it wasn't going to be an S meter issue. Its pretty easy to see how a problem that shows up on LSB as opposed to the other two modes points right to the 7.8mhz section.

    thanks for all the responses.
    LC
     
  10. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    ok this is hard to post.

    I WAS WRONG!!!

    damn i hate to be wrong.

    It wasn't CT2.

    there is an issue with the cable or the placement of that cable, or both, that is creating a problem with this Uniden Washington.

    I don't know if it's just this one, or if it's a Philippines Washington problem, or what, but the placement of the yellow jumper coax that connects the carrier oscillator circuit to the "TP3" portion of the radio very much effects the other modes.

    As far as i can figure, it has to do with a badly shielded cable combined with being very close to the FT1 crystal filter.

    this was confirmed by moving the cable back and forth while watching the S-meter.

    changing C104 and CT2 for new parts seemed to help, but it's now easy to see that this cable's placement with regards to FT1 absolutely has an effect on the receiver sensitivity of the different modes.

    i need to experiment with a better shielded cable and different orientations as im sure that is the key to this problem.

    I can't be the only one who has dealt with this.
    LC
     
    Shadetree Mechanic likes this.
  11. Dmans

    Dmans Well-Known Member

    Joined:
    Jan 22, 2017
    Messages:
    319
    Likes Received:
    189
    LC,
    Sounds like you are on the right track. And on the bright side………….At least you didn't solder your thumbs together to get there!

    73's
    David
     
  12. Klondike Mike

    Klondike Mike Well-Known Member

    Joined:
    May 31, 2010
    Messages:
    689
    Likes Received:
    280
    I had a problem with a TRC457 having a flakey FT1.
     
  13. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    3,047
    Likes Received:
    1,297
    thanks for the replies and the laughs.

    KM, this was a first for me. I wonder if it could happen in any radio and i've just been lucky or if it's just Philippines Washingtons or what.

    All i can say is that when that cable was moved closer and further from FT1, you could see the S meter moving in a corresponding manner.

    i wondered if the shielding on the cable wasn't up to snuff so i changed it out.
    made no difference.

    i ended up tying it over some RX cans so that it won't move and it worked perfectly.

    so, if others are having weird S meter issues with this chassis, check that yellow cable placement.
    LC
     
    Shadetree Mechanic and Dmans like this.
  14. Klondike Mike

    Klondike Mike Well-Known Member

    Joined:
    May 31, 2010
    Messages:
    689
    Likes Received:
    280
    I suspect the incidents of "new experiences" on these vintage radios will only increase in the future. Components besides electrolytics will start to break down giving repair professionals and hobbyists busy for many years to come.
     
  15. Rwb

    Rwb Active Member

    Joined:
    Jun 30, 2018
    Messages:
    348
    Likes Received:
    214
    Uhh soldering fingers haha.i worked at eagle pitcher in 73 for a winter.i soldered terminal posts on battery cells.i had a leather like thumb from pushing solder and copper terminal on the carbon bar.
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!