Recent content by amptramp

  1. amptramp

    Channel Master 4401G FM antenna

    The question came up about the reason for twisting twin lead. If you don't twist it, any magnetic field that appears from the outside world can induce a voltage in the twin lead and twisting the twin lead causes the voltage to be reversed in each twist. If someone is operating a welder nearby...
  2. amptramp

    Dynaco FM3 Front end won't align

    The FM-3 has a rather different oscillator. It is set up as a tuned-grid oscillator with feedback from the plate but the oscillator plate is tied directly to the screen grid of the mixer. This may require more power out of the oscillator so a weak tube may be the culprit but before you do...
  3. amptramp

    Marantz 105 bulb replacement

    Most LED's have a very low maximum reverse voltage, typically around 5 volts. Most lamp supplies are 6.3 VAC or up to 8 VAC and this would destroy LED's even with dropping resistors. One trick that is successful is to operate two lamps back to back so the most reverse voltage they see is the...
  4. amptramp

    Tuner alignment instruction

    Here is the Sencore manual: https://bama.edebris.com/download/sencore/sg165/Sencore%20SG165%20O&M%20Manual.pdf
  5. amptramp

    KLH Model 57

    The top thread (how to clean an analog tuner) will give you some instructions on how to clean a variable capacitor and remove the crud that collects on the vanes. Since this stuff likely has a relative permittivity of greater than 1, this will reduce the capacitance and bring your tuning back...
  6. amptramp

    Rc1205 static

    If you were connected to an antenna, you may have had lightning damage the mica trimmers. I fixed static that randomly occurred in a car radio once by opening the RF trimmer up to minimum capacitance then tuning it again for optimum signal strength. The ball on the end of a car antenna is not...
  7. amptramp

    Magnum Dynalab Sleuth 95

    I probably had the cheapest entry into the Magnum Dynalab world. I bought a Sleuth 95 at a garage sale for $4. This is the schematic for the Sleuth 95 and the features that show up in the schematic are triple gang tuning via varicaps, control of gain from the upper gate of the dual-gate MOSFET...
  8. amptramp

    Trio KT-900 - trying to fix problem tuning stereo

    As an explanation, "LO" means local oscillator.
  9. amptramp

    What's on your FM tuner right now?

    What's on my tuner right now? A potted plant.
  10. amptramp

    Tuners?

    Now I've done it. I added my 28th tuner today, a TEAC T-X150 with decent FM but no sound at all on AM. But for $15, it became mine, all mine.
  11. amptramp

    Audiophile Radio Experience?! Tell me about a moment of amazement while Tuning In.

    I was a dedicated AM radio DX'er looking for distant stations and a copy of Radio - TV Experimenter containing White's Radio Log never left my side. I managed to listen to 135 stations in that book including an impressive haul of 640 KFI Los Angeles from my home in Toronto. I thought that...
  12. amptramp

    Dumb question about AM/FM alignments.

    Some schematics carry this information with the adjustment arrow symbol between the windings pointing up for tuning coil from the top or down for tuning from the bottom.
  13. amptramp

    Audiophile Radio Experience?! Tell me about a moment of amazement while Tuning In.

    A number of years ago, I picked up a Sherwood 2100 II tuner at a London Vintage Radio Club meet (in London ON Canada) for the grand total of $20. I played it through the aux input of my H H Scott 340B and it showed its superiority to the good tuner that was in that receiver. This is one of...
  14. amptramp

    External signal strength meter?

    You can add an external tuning eye tube as shown here: https://www.antiqradio.com/post_attaching-a-magic-eye-to-your-radio.html My favourite tuning eye tube is the 6AL7GT. It has two square sections at the top which can have one connected to ground and the other to the discriminator / ratio...
  15. amptramp

    FM Broadcast signal components

    My two IG-37 and IG-112 and SG165 object to this statement! So do my twelve oscilloscopes. And my DMM's multiply like rabbits, but that's OK, they're small, just feed them batteries and they are happy.
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