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Recent content by nomadradio

  1. nomadradio

    142 gtl issue

    The 148GTL isn't just one radio, it's a whole product line covering 40-plus years. Much like motor vehicles the internal layout, wire colors and design change over the decades. Not every year like automotive models, but a 1979 Cobra 148GTL is very different on the inside from a 2009 model...
  2. nomadradio

    Parallel connection of Plate Transformers

    The old "100-Watt bulb in series" test will work. If you get the phase backwards, the transformer becomes a low-value resistor and the bulb will be bright when power is applied. The bulb limits current to a safe value. And if you get the phase correct between the two secondaries the bulb will...
  3. nomadradio

    is it a grant or cobra

    Yeah. Somebody put a Timex face on a Rolex. 73
  4. nomadradio

    knight kit t 60 help

    Are you absolutely, positively sure that none of the new electrolytic caps are installed with the polarity backwards? When that happens, the capacitor will usually break down internally and become a dead short. A resistor feeding into that capacitor will smoke after the capacitor fails. Back...
  5. nomadradio

    TRAM D201A adjustment points? Alignment question

    Best clue for a "carrier" on sideband transmit is a frequency counter inline with the radio's coax. If your sideband carrier is stable, and on the channel frequency the fault is probably with the balanced modulator board. If the frequency is unstable, and not really near the selected channel...
  6. nomadradio

    3cx1500a7 max exhaust air temp?

    That's pretty much the way I'm used to doing it. 73
  7. nomadradio

    is it a grant or cobra

    It's a frankenradio, alright. The PB208 should be a big performance improvement over the Malaysia pc board that this radio came with. Really looks like the front panel and counter module got grafted onto the Uniden main pc board/chassis. 73
  8. nomadradio

    Cobra 148 gtl SSB Audio Flutter Malaysia Model

    Garble on receive audio? Or transmit audio? 73
  9. nomadradio

    3cx1500a7 max exhaust air temp?

    The max temp for that tube is about twice what you're seeing. Sounds to me as if you're in a reasonable safe zone. 73
  10. nomadradio

    Calling on some wisdom from the group....

    Not so different from making a 45 year-old foreign sports car your daily driver. A parts donor or two can prove valuable down the road. 73
  11. nomadradio

    3cx1500a7 max exhaust air temp?

    Gotta wonder how much the temperature of the tube's exhaust air will drop between the tube and the temp sensor. I'd figure 110 C air sounds like a safe zone. But the surfaces of the tube are bound to be hotter than the air passing over them. Just don't know how much. Any idea what volume of...
  12. nomadradio

    2x 4cx300a note

    Like this? https://www.ebay.com/itm/116094116631?mkcid=1&mkrid=711-53200-19255-0&siteid=0&campid=5336136228&customid=&toolid=10001&mkevt=1 We also have a relay that installs in a CB or "10-meter" radio to key an external amplifier. My advice is that the higher the drive level, the more...
  13. nomadradio

    Maco 300 gets 47-year tuneup.

    IT (was) ALAYEEEV! For about a dozen keys of the mike, and one of the 1976-made 8950 tubes flashed and died. Forever. The owner says he has some tubes, so we'll pick up where I left off once he drops them off. I'm about ready to call this "Maco Syndrome". Works great until 48-year old...
  14. nomadradio

    High swr reading

    He's right. There is a limit to how close you can get metal to those loading coils before it disrupts the coil's tuning. That will drive up SWR. If you don't believe me, wrap your hand around one of those coils and see the SWR change from that alone. 73
  15. nomadradio

    Tram D62/Cobra 132 no transmit on 36-40

    Only effective way I know to tweak the VCO's tuning-voltage adjustment is with a 'scope. The schemo is here: https://cbtricks.org/radios/cobra/132xlr/graphics/cobra_132xlr_sch.pdf This radio has a somewhat-wacky PLL setup. In most SSB CB radios you have a carrier crystal that's above the...