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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

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  • 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. Two considerations: Number one you will lose 3 dB of each signal in the passive splitter. This may not make much difference if the distances are moderate. Number two the splitter will protect the output stages from the opposite signal but expect some intermod. 2F1 - F2 and 2F2 - F1. Just make sure you don't use those frequencies for any other device. You will get some intermod with two antennas anyway so your one antenna scheme is pretty much a wash. Best Regards, Larry Fisher
  2. Hi Fabian, -The audio sections of the 1st and 2nd generation are the same. -Service is the same. -The 200 series emulation might have small improvements in the 2nd generation. The emulation was never perfect, hence the tweaks. After all, the 200 is full analog and the SM is digital, imitating the 200 series. The newer SM is probably a closer imitation. Whether a Golden Ear could hear it is another question. It definitely sounds better than "OK". Others should chime in with real world opinions. Best Regards, Larry Fisher
  3. Hi Ben, Just to add to this; if one of Dean's thoughts is the problem, a weak battery might prolong startup just enough to trigger a fault. The good news is that once the unit is up and running it should continue to work. Best Regards, Larry Fisher
  4. Hi Ben, Try using the "bad" batteries again and see if the problem follows the batteries. I doubt that it is due to batteries. However, I'd switch the good and bad batteries back and forth several times just to triple check. It is possible that the batteries have high resistance or low voltage and the boot up sequence is not completing properly. Startup briefly pulls higher currents. If the DSP itself were bad I would expect the DSPerr would continue rather than come up between the one and the three in the boot-up countdown. If one set of batteries does it again, try charging them and trying the test again. That is just for info. If they start working when charged, I still wouldn't trust them. Assuming the HMa doesn't act weird again, try heating and cooling the unit to see if that will cause a solder joint problem. In the summer, putting the unit in the sun can get it nice and toasty. Then putting it in the refrigerator will stress the connections in a different direction. If doing that several times doesn't do anything, try rapping it with a screwdriver handle or something short of a 4 lb sledgehammer. Rap it in all directions with the unit on and off. You are trying to make the unit fail in your free time rather than when you are in a critical situation, i.e., somebody is paying you money to do your job. Frankly, I hope it is the batteries but that is a low probability. Best Regards, Larry Fisher p.s. I'll copy this to Dean in service and see if he has run into anything like this. Hi Enko, I saw your post after I posted to Ben. Maybe Dean has an idea if this is happening more than once. Best Regards, Larry Fisher
  5. Hi Peter, The antenna is most probably tied to an inductor that goes to ground. That bleeds off stray static and protects the output stage. The inductor will be 10 or 20 turns of fine wire and it will measure less than an Ohm when tested with a multimeter (DC Ohms). At the operating frequency, it will be part of the tuned output filter or will look like a high reactance, i.e., not there. In sum, not to worry, as long as the range is "normal". Best Regards, Larry Fisher
  6. My problem is that I can't figure out which one I like best. Thanks, Johnny. Larry F
  7. If you are looking at a purchase of a piece of used equipment that still is a large investment for you, it is worth a free phone call to the manufacturer's service department to see if the gear is still supported. Some RF products have been legislated away and can no longer be legally supported, some products will use parts that aren't available anymore and some manufacturers just stop support because it's too much hassle. A call or email is free. If you can't get good info, that tells you something also. Best Regards, Larry Fisher
  8. Let me clarify some points. Gain from a directional antenna is different from the gain of an amplifier. An amplifier gains up both the desired signal, in band but undesired RF signals, and any undesired noise. Too much of this amplifier gain can upset the squelch circuits, diversity system, sliding filters (Lectro) and other parts of the receiver system. By too much gain, we are speaking of more than say a total 6 dB of amplifier gain after cable losses. Since off frequency signals may also be gained up by the amplifier, intermod can also increase. Antenna gain is a horse of different feathers. Antenna gain is directional gain and is largely noiseless in the sense that the desired signal may increase but undesired signals (noise floor) are largely rejected by the amount of gain of the antenna and background noise is reduced too, i.e., an antenna with 4 dB of directional gain increases the desired signal by 4 dB but the noise floor does not increase. If an interfering signal is in the null of an antenna, you would get even more rejection. In sum, don't attenuate the gain (directional antenna gain) of a passive antenna. Do attenuate amplifiers for active antennas at the receiver end of your cabling if you have excess gain of say 5 dB or more. Excess gain is the amplifier gain minus cable losses and splitter losses. Finally, it is hard to overload the inputs of modern receivers with a desired signal due to robust front ends and AGC (Automatic Gain Control) in digital receivers. However, gaining up the noise floor can cause problems as discussed above. The final comment => You don't need a 3 dB attenuator. Best Regards, Larry Fisher
  9. What problem are you trying to solve with 3 dB attenuators? LEF
  10. The 7 dB number is for the upper frequency end (600 MHz+) of U.S. frequencies. If you are at the lower end (500 MHz) 6 dB is correct. Best, LEF
  11. Two points: 1. RG-8x is not equivalent to RG-8, a much larger cable with lower loss. 2. The LMR-240 is an improved RG-58 equivalent with 7 dB loss/100 feet. It is not as low loss as RG-8 or Belden 9913F, both 0.400" cables. Best Regards, Larry Fisher
  12. Just a reminder: Loss per foot is inversely proportional to cable diameter. There is no magic that will give you a low loss, small diameter cable even if the cable is made from unobtainium. Best Regards, Larry Fisher
  13. Too funny but the kids won't get it. That's good, I suppose. Lef
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