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About LarryF

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    Hero Member
  • Birthday 12/11/1943

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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.

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  1. I think "abandoned" is when the manufacturer no longer "services" the particular product. Service includes repair, manuals, and general support. Just not making it any more is not abandonment. I've always thought a company should service the product until they are forced, kicking and screaming, to give it up. That can be due to parts that, after many years, are no longer being made or parts that have become so expensive that it is not worth it to the customer to pay for a repair. Or the one technician that can fix the unit is 92 years old and has gotten very cranky. I have personally spoken to a large user that couldn't get multiple products serviced (factory checkup) after 5 years. I think that is a poor business choice. As an example of the difficulties of long term support, the 195 series is still being 95% supported as well as the ancient 185 series. Why 95%? Because the last American crystal manufacturer that would make special frequency crystals for those units has gone out of business. If it's not a broken crystal or a frequency shift required by the FCC auction, you are probably covered. If it be the case, we and you are up Paddle Creek. Best Regards, Larry Fisher
  2. Yep, LEF
  3. Hi Derek, The 4 way splitter has a loss of 6 dB. If you only use 2 of the 4, the loss is still the same. The 50 Ohm terminators will make only a negligible improvement. With passive combiner-splitters you always lose. Active units just use amplifiers to make up for the losses. We talk of dB of loss but another way to think about it, is that the loss is just the number of splits or combinations. Half power for a two way, 1/4 for a 4 way, 1/8 for an eight way, etc. Best, Larry F
  4. Hi Ant and John, There is about 30 to 35 dB of isolation between the input ports with a mini circuits (or Lectro) 2 way splitter-combiner. This is equivalent to having two separate antennas about 5 feet apart. There will be a small amount of 3rd order intermod (as with separate antennas) but rudimentary frequency co-ordination will prevent this from being a problem. You will also have this low level intermod with active combiners. The only downside is the 3 dB loss with a 2 way splitter-combiner but if you can live with 70% of normal range, then it is a viable option. Most times you won't even notice the slight range reduction. Don't ever use a simple T adapter between two transmitters: Intermod will be terrible, power losses will be more than 3 dB and the transmitters may very well go unstable, spewing random frequencies near and far. Best Regards, Larry F
  5. The SNA 600 has what are called fat elements (arms). If they were narrow wires for elements, they would be sharply resonate at a single frequency. Being "fat", the bandwidth is spread out over about 50 MHz. Ideally, you would center the arms between the two contiguous blocks you were wanting to use. Why does the SNA antenna work well over 4 blocks? It is the definition of "well". There will be 4 or 5 dB of sensitivity loss when you exceed the 50 MHz bandwidth. When you consider that RF levels jump up and down by 30 to 40 dB as you walk around and the usual setup has excess RF signal of 50 dB or so (50 dB more than minimum usable signal), it is obvious why a mis-tuned antenna will still perform. In a long distance setup, with low signal levels and little RF noise in the surroundings, (Flat Rock, Montana), the properly tuned antenna will give you a slight edge in range. For 98% of the time in typical use, a coat hanger bent in interesting shapes soldered to a BNC would work just fine. For those of us that are anal and use both belts and suspenders, having the whole RF chain as perfect as can be is comforting. If you really want to cover all four blocks perfectly, a truly wide band antenna such as an LPDA (Lectro ALP600 or others) is a fine solution. Walking around with a pair of paddles on your shoulders will result in good solid RF and knowing glances from those working around you. So, tune the SNA 600 to the middle of your blocks and go onward. Or cut a coaxial antenna to the middle of the blocks. Or there's the coat hanger option also. Best Regards, Larry Fisher
  6. Some engineer will answer tomorrow Wed. Lef
  7. I'll check with Lectro crew since we were in that area and packed up after the get together. LEF
  8. Back of envelope calculations give 6 hours on Eneloop NiMh and 7+ on Eveready Lithium assuming 4 hours on alkaline is correct. I assume Eneloop will be the usual choice. Best, Larry F
  9. Hi Kosty, Given what you have posted, I see no reason for this weird behavior. The fact that a Sennheiser with Lemos is acting the same way almost says it is after the wireless receivers, such as a headphone amp or mixer. Another wild ass possibility is high level ultrasonics in your testing area but changing locations should put that to rest. This has me stumped. By the way what is "pin 3-NF"? NF is a new one on me. Best Regards, Larry Fisher
  10. Best comment of the day. Best, Larry F
  11. The feed point of the lpda is at the small end of the antenna. It has to be balanced, hence the balun in Mark's schematic. However, regular coax is unbalanced and having coax hanging at the front small end of the antenna will distort the pattern. A clever way of accomplishing a balun is to run coax down the exact center of the lpda coupled to one leg of the dipole array (soldered along its length) with the connector at the big end. The connected coax should move perpendicular to the final dipole arms, not in the direction of the arms or next to them. Lectrosonics uses a four layer board with internal microstrip acting as the balun. Others use external coax soldered to one layer of the dipole arms. Either works. It is very difficult to measure or characterize the performance of an antenna without a very sophisticated setup. About all a hobbyist can do is follow the directions carefully. A coat hanger soldered to a coax cable will work 90 per cent of the time. It doesn't mean it is a good antenna. Just follow directions. There are a lot of solid reasons that things are positioned just so on antennas. Happy Experimenting, Larry Fisher
  12. Try a 1K resistor. That will give you 12 dB more output from the mic. Any noise after that should be self noise of the mic, which is a bit higher than that of the normal output mic Best Regards, Larry Fisher
  13. 14. SM and SSM are splash proof. (TA5F on SM will not stand submersion but will recover. Battery contacts on SSM can get wet with submersion but can be wiped off.) 15. Lots of backwards compatibility between current and very ancient Lectro systems. 16. Old (+15 years) units are still serviced. We are, however, having difficulty getting good quality anthracite coal for the steam boilers. Best, Larry F Stoker First Class
  14. Hi Axel, Hma design can provide higher currents than conventional 48 Volt Phantom power setups with less voltage drop. It starts out at 42 Volts since the voltage drops less under load. As you sumised, voltage isn't the problem. The Hma is not a balanced input though it presents a balanced resistive load to the mic. As I remember, pin 2 is audio in and pin 3 is a resistor to a big capacitor to ground. My guess as to what is going on, is that the mic is putting out audio on one pin only (pin3) and that pin is not the hot pin on the Hma. Into a conventional input, audio on either 2 or 3 produces a good signal. You can test this with a phase reverser at the mic to see if it now works with the Hma. The mic is still not right. Best Regards, Larry F. p.s. "Guess" is the most important word in my post above.