• 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.

Search results

  1. dudmuck

    SDR questions

    Why is all the ham SDR for HF? I think because thats where the market is. (demand) But for VHF/UHF SDR, you need to go where the students and researchers go. Such as my Ettus SDR box, for which I put the RF board which covers 64MHz to 2.2GHz. It will do any modulation that the software...
  2. dudmuck

    Duplex Dweller

    If you're running on a single band, A dipole would be better than a screwdriver. Screwdriver requires a counterpoise, some big metal sheet. Cookiesheet? Or just get a 102"whip and mount it on some piece of metal like that if your only on 11/10m. A magnetic loop is probably the best antenna...
  3. dudmuck

    Va Earthquake

    Photo of devastation: Photo of devastation from the East Coast earthquake | Grist
  4. dudmuck

    Billionaire Warren Buffett is Right !!

    Sure, there are some welfare abuses. But its small potatoes compared to our military budget: We spend as much on military as the rest of world combined. This is unsustainable to have such large military spending while simultaneously keeping taxes on the rich at such historically low levels.
  5. dudmuck

    Mosfet Amp

    A copper board such as that is not "one big ground", unless it has plated-thru vias at regular intervals. For some perspective: a 4inch piece of 20AWG wire has 6ohms of inductive reactance at 27MHz. (at Inductance of a Straight Wire: A Calculator) Braided wire has lower inductance because of...
  6. dudmuck

    Mosfet Amp

    The braid is there precisely because the board is one big copper board. Meaning the board has no plated-thru holes to the bottom layer, also known as "vias". So because of that, there is insufficient ground connection between the pills and to the (-) power lead, which is compensated for by...
  7. dudmuck

    Mosfet Amp

    The efficiency is horrible, if it needs 300A at 20V, that would be 6kw. For 1kw out? that would be 16% efficiency. ok, if its 2500w pep then you still dont have more than 40%. Those new pills from NXP or freescale are at least 70% efficient.
  8. dudmuck

    Transistor (BJT/FET) manufacturer comparison

    Indeed, with devices such as MRFE6VP61K25H that operate up to 600MHz. We should be talking about running a kilowatt on FRS instead of "noise toys on FRS". Freescale and NXP are at the top. ST, Microsemi and M/A COM are runner's up, but still good parts. Toshiba doesn't do any RF power...
  9. dudmuck

    EME on 11meters sked wanted

    Its already been done on 40 meters, using HAARP. ‪Moonbounce‬‏ - YouTube However, this HAARP site can have effective radiated power in the billions of watts. Yet, it should be easier on 11 meters, considering its closer to VHF. Take any 6 meter EME setup that works, and size-up the...
  10. dudmuck

    RF burn from RK56 lip guard

    Maybe what you call a "box" is whats known elsewhere as a pick-up "bed". You should also try a strap between cabin and bed/box. Often such vehicles have cabin and bed on rubber mounts, and they only have minimal DC connection between them. And for 27MHz, its like no connection.
  11. dudmuck

    why don't they make HTs that can do SSB?

    Sure, you now have complete radio on chip, such as freescale MC13260. But you're never going to shrink an antenna for HF bands and still have it efficient. The RF chip in smartphones operate on UHF, where antennas are small. The bandwidth of signal is relatively wide, so not as much concern...
  12. dudmuck

    Jumper wire

    Borrow a dummy load that can handle the watts from your amp. Try it instead of your antenna. If you still have squealing, then probably you have a bad coax shield connection. But if you dont have squealing any more with dummy, then you likely need a few ground straps on your car chassis...
  13. dudmuck

    Capacitors

    Any capacitor directly exposed to vehicle voltage should be at least 16v. Probably (hopefully!) those 12v caps are not used for that. good design practice actually says a capacitor should have double the voltage rating of what its actually going to see in service. More important is what...
  14. dudmuck

    Sideband CB Radio

    The frequency drift on SSB doesnt bother you? you must be ok with adjusting the clarifyer now and then. maybe its hit and miss. probably the only way to be sure is to put it in a temperature chamber.
  15. dudmuck

    Who knows about the Conjugate Match?

    Did anybody answer it in simple terms? Take an example of the fact that power utility company drives mostly an inductive load because there are lots of motors that run on electricity. So sometimes you will see capacitors on utility poles or substations to cancel out the inductive load. If...
  16. dudmuck

    1250W CW from a single power FET!!

    NXP just one-upped on freescale: NXP puts the 'extreme' in extremely rugged LDMOS transistors You can see them in the video, abusing the device under the most extreme conditions without damage. Gone should be the days of blown devices due to broken coax or damaged antenna.
  17. dudmuck

    FCC Takes Strong Stance Against Radio Jamming, Issues $24,000 Fine to California Man

    There are two sides to every story. You also have to wonder about business which puts major operations onto a shared frequency.
  18. dudmuck

    Drug War A Failure - Legalize Today !!

    "vastly superior" industrial product might be over-stating it. More importantly, Connecticut senate approved pot decriminalization by just one vote. Where possession of less than half ounce only results in monetary fine. Hopefully more will weight the costs & benefits of keeping it...
  19. dudmuck

    Question of the order of equipment on coax

    from ANTENNA TUNER - HOW TO USE AN ANTENNA TUNER
  20. dudmuck

    1250W CW from a single power FET!!

    Thats the truth. Take for example Ameritron ALS1300, with power supply just barely capable of supplying the required current. In any case, current limiting on power supply is required. Firstly and foremost, to protect the power supply, but if you rate a power supply with double capacity you...