Page 2 of 3 FirstFirst 1 2 3 LastLast
Results 11 to 20 of 25

Thread: TrueTone D1143 Radio to Amp

  1. #11
    Join Date
    Mar 2010
    Location
    Boulder, CO
    Posts
    7,778
    Thanks
    19
    Thanked 486 Times in 449 Posts
    Rep Power
    14818761
    Sign in to disable this ad
    Quote Originally Posted by arcaxis View Post
    Yep, power supply filter choke coil.
    "Filter choke" was the exact phrase I had in mind. Thanks for confirming that.

  2. #12
    Join Date
    Dec 2002
    Location
    Massachusetts
    Age
    71
    Posts
    4,520
    Thanks
    11
    Thanked 228 Times in 209 Posts
    Rep Power
    10181459
    The 6SA7 and 6SK7 can be removed. Those are for the RF and IF stages.
    The 6SQ7 can stay if you use its triode as your first stage in the amp, but it isn't going to give as much gain as two stages of your 12AX7 which can be wired for 6.3vac.
    The 6J5 is the phase inverter for the push/pull 6K6's and the 5Y3 is the rectifier.
    The 6U5, if you got it with the radio is a 'magic eye' tube used for tuning stations in. It would be neat to use it for audio signal indication, but it's in the detection circuit.

    If the speaker doesn't work out you might look at putting a resistor in place of the coil in the power supply circuit. An actual iron choke would likely filter better, but a resistor may suffice. I've done this years ago with a similar vintage radio fix. Winding resistance shows 900 ohms. A 1000 ohm wirewound resistor of a hefty wattage would be worth a try. The old multi-section electrolytic can could be replaced with a couple higher value (20-25uf) caps which may help DC filtering. Note the voltage rating on the schematic when replacing.

    The attached PDF might help a bit
    Nostalgia Air: Western Auto Supply Co. - D1143, Issue A
    Attached Files Attached Files
    Mark.......

  3. #13
    Join Date
    Dec 2002
    Location
    Massachusetts
    Age
    71
    Posts
    4,520
    Thanks
    11
    Thanked 228 Times in 209 Posts
    Rep Power
    10181459
    - Some 'chop' points marked in red and pull the tubes I mentioned in the previous post.
    - Change the 'phono' jack to a 1/4" jack and put switch to 'phono'. Try it with some pedals that have some gain.
    - The 'optional cut' is if the tone circuit it goes to takes out high end of the guitar. Maybe try it with and then unsolder the 68000 ohm resistor off the pot to see if it changes anything.
    Attached Thumbnails Attached Thumbnails usa_western_auto_d1143_sch-jpg  
    Mark.......

  4. The Following User Says Thank You to arcaxis For This Useful Post:


  5. #14
    Join Date
    Aug 2005
    Location
    U.K.
    Age
    33
    Posts
    19,390
    Thanks
    1,198
    Thanked 1,014 Times in 895 Posts
    Rep Power
    1000000
    If it works out anything like the transistor radio guitar amp mods, it'll thank you for putting a treble booster in front of it.
    Looking forward to hearing how you get on.
    ---------- Steenaudio Website ----------

  6. #15
    Join Date
    Dec 2002
    Location
    Massachusetts
    Age
    71
    Posts
    4,520
    Thanks
    11
    Thanked 228 Times in 209 Posts
    Rep Power
    10181459
    Rather than put a wirewound resistor in in place of the speaker coil, maybe a mod to the circuit I have circled in red. Still use about a 1000 ohms resistor, but maybe a 1 or 2 watt jobby.....
    Attached Thumbnails Attached Thumbnails 5f10-jpg  
    Mark.......

  7. #16
    Join Date
    Jun 2011
    Location
    N.W. Indiana
    Posts
    1,037
    Thanks
    20
    Thanked 19 Times in 18 Posts
    Rep Power
    6963833
    Thanks, I’ll give it a go.
    Wow, now I feel really stupid. Thanks.

  8. #17
    Join Date
    Jun 2011
    Location
    N.W. Indiana
    Posts
    1,037
    Thanks
    20
    Thanked 19 Times in 18 Posts
    Rep Power
    6963833
    Going through a lot of work to save a few bucks.

    20180922_230742-jpg20180922_230750-jpg20180922_230758-jpg

    20180922_230742-jpg20180922_230750-jpg20180922_230758-jpg
    Wow, now I feel really stupid. Thanks.

  9. #18
    Join Date
    Jun 2011
    Location
    N.W. Indiana
    Posts
    1,037
    Thanks
    20
    Thanked 19 Times in 18 Posts
    Rep Power
    6963833
    As to fuses, what amp should I use? I was thinking a 2amp would do.

    And I have 3 fuse holders that I could use. Which one?

    20180922_230915-jpg20180922_230920-jpg20180922_230931-jpg20180922_231010-jpg


    I'm sure they have proper names, have no idea what they are. Any help?

    Thanks!
    Wow, now I feel really stupid. Thanks.

  10. #19
    Join Date
    Aug 2005
    Location
    U.K.
    Age
    33
    Posts
    19,390
    Thanks
    1,198
    Thanked 1,014 Times in 895 Posts
    Rep Power
    1000000
    Hey man,
    I didn't see your last posts until now. Not sure why.

    What was the outcome with this? Did you get up and running?
    ---------- Steenaudio Website ----------

  11. #20
    Join Date
    Feb 2009
    Location
    northampton uk home of Dr Who and Blackstar Amps!
    Posts
    9,913
    Thanks
    1
    Thanked 660 Times in 624 Posts
    Rep Power
    9269082
    I too found this thread late but Mark seems to have done a bang up job!

    Cut my apprentice teeth on similar radios, not many American models, the odd Philco but I always hated their weird schematic layout and found them hard to follow! The attachment is also low resolution. Is that a "concertina" phase inverter? If so the amp will have very little gain.

    The most "elegant" way to sort a radio like that is to strip out all the RF components save the valve bases and tagstrips. Then the bases can be used either for an octal double triode like the 6SN7GT or use an octal base to make a B9A adaptor (the ECC83 only needs 8 pins) Or, strap an RF pentode as a triode, or two.

    The energized speaker is indeed a filter choke but the rectifier current causes hum and so there is usually a humbucking circuit in the secondary path. The speakers usually had a Paxolin "spider" and thus a high cone resonance, doubt it will sound good.

    Fusing? 2AT for mains input and 100mA T for the HT...DO fit an HT fuse!! Since there is an IEC mains con'' best to stay modern and use 20mm fuses.

    I have to say, OP did not read as terribly experienced with electricity? I do hope the lack of further information is not a sign of some terrible happening?

    Dave.

  12. The Following User Says Thank You to ecc83 For This Useful Post:


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Replies: 2
    Last Post: 08-22-2013, 11:14
  2. Replies: 18
    Last Post: 07-12-2010, 05:32
  3. Anyone used truetone hi bias cassettes?
    By westgate in forum Analog Recording & Mixing - Tape & Gear
    Replies: 4
    Last Post: 01-17-2010, 16:43
  4. Local Radio Play for major radio.
    By qb2k5 in forum Marketing Your Music / Publicity
    Replies: 2
    Last Post: 08-10-2006, 17:37

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •