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LarryF

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About LarryF

  • Rank
    Hero Member
  • Birthday 12/11/1943

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    fisherlarry@gmail.com
  • Website URL
    http://lectrosonics.com

Profile Information

  • Location
    Rio Rancho, New Mexico
  • Interests
    Classical music, fast cars and Maine Coon cats
  • About
    I have been chief janitor at Lectrosonics for 40+ years.
  • Interested in Sound for Picture
    Yes

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  1. Unfortunately, unlike the FCC, the test labs don't publicly post the flora that they are testing but deep state leaks indicate a bumper crop of the seeds of Kali tragus in the New Mexico soil. With a few more months of increasing moisture plus the usual warm sunshine, the first grass green shoots will emerge. Best Regards, Larry Fisher
  2. RG-8X is .250" in diameter and RG8 is .400" diameter and half the loss per length. Best Regards, Larry Fisher
  3. Hi Derek, Now that you added amplification, I agree totally. Just make sure it is a high overload amplifier, i.e., pretty high current (power). It's not even necessary to use RG-8X (though it is the best of the .250" cables). Good ol' RG-58 will work fine, if you balance the amp gain and cable loss. Best Regards, Larry Fisher p.s. If the amp manufacturer or amplified antenna manufacturer doesn't spec third order intermod values, it's probably a poor choice.
  4. Cable loss is inversely proportional to cable diameter. RG8X is a smallish cable (.250" similar to RG-58) and will be relatively high loss over long runs. Don't confuse RG-8X with RG-8, which is a .400" cable with less loss over long runs. There are other .400" inch cables that are more flexible and have foamed dielectrics for a little less loss, emphasis on little. Google a cable loss table and figure out what kind of losses you can stand and make your choice. There rarely is a free lunch at the RF table. Best Regards, Larry Fisher
  5. Our attitude is "Thou shall not Fxxx around with lithium batteries." There's enough uncertainty with Chinese knockoffs and fake certifications on batteries already. I do truly understand your point, but we've gone the belt and suspenders route with lithiums. Best Regards, Larry Fisher
  6. Thanks for the helpful pictures. Best Regards, Larry Fisher
  7. I'd cut the jumpers in half and solder wires to the jumper ends. Though maybe not necessary, a small O-ring around both the female connector and small wires could support the wires' weight and protect them from violent shocks. Kind of a belt and suspenders approach. The good thing about this approach is it is easily reversible and doesn't require unsoldering the connector and maybe damaging the pad and trace. Best Regards, Larry Fisher
  8. Any combined transmitters need an isolator of some kind, either passive or active. If you simply connect the two transmitters together with a tee, best case is that the output of both transmitters will be greatly reduced. Worst case is that you will let the magic smoke out. Best, Larry F
  9. Since you are shown as being in Taiwan, I passed this on to the repair crew at Lectro to see how this should be handled. It usually is an alignment problem in the the SMQV. Lectro is 95% shutdown during the Xmas to New Year holidays so it may be a week before they get on this. Best Regards, Larry Fisher
  10. You probably can do the equivalent of moving the receiving antenna, as described above, by moving the transmitter up and down until you get a peak RF level. Again, the reason for looking for a peak is to insure you haven't created an interference at the receiving antenna, i.e., a dropout. I would think you could get a reasonable comparison between the quarter wave and the LPDA. Also, the quarter wave antenna needs a ground plane to work against, such as a receiver housing (not a good ground plane but better than nothing). It sounds like you just have it at the end of cable. Any bags of water (
  11. The 941 MHz band is US only except Britain has a band at 960 MHz, as I remember. Best Regards, Larry Fisher
  12. You are correct in that the delta is too large. You should see an LPDA improvement of only 4 to 5 dB. To correctly measure an antenna's gain, you need an RF anechoic chamber ($100k+) or an outdoor site far from any reflecting objects with a large metallic ground plane in or on the ground. The antenna is placed on a wooden pole with a rope so it can be moved up and down. The antenna is moved up and down so the reflection from the ground plane is in phase and maximises the signal. You are always going to have some reflection from the ground (unless you have an anechoic chamber) so you simply ma
  13. I would expect that the plug that "leveraged" that jack would have bent before the jack broke. That is to say the user would know immediately that too much sideways force was applied and would know the reason for the failure. From the picture it seems possible that overtightening the nut would pull the jack apart in that manner. Experimentally, I guess you would have to get the same jack and brutally tighten the nut to see if that duplicated the failure. Or push a plug sideways in the jack until something failed and see if it looked like the example. Best Regards, Larry Fisher
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