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LarryF

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Posts posted by LarryF

  1. 1 hour ago, ramallo said:

    I guess it depends on whether the 1/2 dipole is at its correct distance. The advantage that I see in the Botwie is that it is suitable for multiple frequencies at the same time and you forget about it, but at the cost of losing gain. But also according to those at Betso it has an SWR of 1.2:1 (I think it is too good ) against the 2:1 (Fair) of, for example, the Lectrosonic SNA600a. Much more efficient the Betso

    The SNA600a is 2:1 only at the band edges. When defining bandwidth, the 2:1 value is a commonly accepted bandwidth definer. Inside that bandwidth, the SNA600a SWR is much lower on the order of 1.2:1. Keep in mind, a tunable bandwidth may be useful in attenuating undesired RF.  "Different horses for different courses" .

    Best Regards,

    Larry Fisher 

  2. The headphone output is quiet and can be used as a line level (1 Volt) output. It is just lower impedance than most line level outputs, which is never a bad thing. I'm missing what is the reticence to use it as a line level output. (??).

     

    It's a minor point but G3/G4 receivers do not have matching equalization and compander time constants to the Lectro IFB. It certainly will work, though.

    Best Regards,

    Larry Fisher

  3. 23 minutes ago, Derek H said:

    Thanks Larry! Do you have runtime info as well?

     

    I thought Energizer was the only game in town (in the USA) for disposable lithium batteries? Did their patent expire or something?

     

    $1 per cell cost savings is pretty huge. I’m pretty sure we’re usually changing batteries sooner than necessary most of the time anyway. 

    Hi Derek,

    The EBL batteries have 95% of the Energizer runtime. For instance, if you have 6 hours of run time on the Bunny Brand, that's 360 minutes. The EBL 95% is 5% less time or .05 x 360 =18 minutes less. So you'd have 5 hours and 42 minutes compared to 6 hours. Or you can just subtract 1/20th of the run time.

    Regards,

    LEF

    p.s. The reason I didn't do run times is we have many transmitters at various power levels and single and dual batteries. In retirement, I'm getting to be pretty lazy.

  4. I bought some disposable AA lithiums from Amazon and tested for power capacity. Total power was a better benchmark since average voltage and Amp hours varied by 8% or so across the three brands. Total power makes more sense due to the switching "power" supplies in Lectro transmitters, since they are like a DC transformer with power in equal to power out (less small losses).

    I bought Eveready as a reference, NINMA since they claimed 3500 mAh, and EBL since I recognized the brand as a larger seller of battery products. The testing rig was a computer controlled battery tester made by West Mountain Radio. The test current was a constant 400 mA similar to Lectro transmitter current drain.

    I also calculated cost, corrected for power capacity using prices off Amazon. Amazon has coupons and scheduled delivery discounts that will vary over time. The corrected costs are as of today, 15 Oct 2023 for 24 batteries purchased at a time.

    Eveready Ultimate Lithium:
    4.418 Watt hour   100% (reference)  $2.79   2.79 corrected 

    EBL Lithium:
    4.212 Wh                 95%                       $1.62   1.70 corrected

    NINMA Lithium:
    4.146 Wh                 94%                       $1.75   1.86 corrected 
     
    Conclusions: The off brand lithiums would be a cost viable choice if you don't need the last few minutes of run time. A situation where NiMh won't run long enough but an Eveready Lithium is more time than you need.

    The NINMA brand had the highest current capacity but the average voltage was 8% lower. That reduced its power capacity. Eveready had the highest average voltage making it the highest capacity. EBL had good current and voltage putting it in the middle. EBL was the most cost effective.

    YMMV
    Best Regards,
    Larry Fisher        

  5. 2 hours ago, Paul F said:

    Most interesting. They are both rated by their respective manufacturers @ 2500mah.  But the Energizer lasts 60% longer. That's huge. Nice test Louis.

    The difference is in initial battery voltage. The lithium is higher voltage so the current draw is lower due to the fact that the power supply in the unit is a switching power supply. Switchers convert power in to power out. So a higher voltage can draw less current for a given power in. For instance, a switching power supply running from a 12 Volt battery could draw 5 Amps and put out 5 Volts at 12 Amps, if it were 100% efficient. 60 Watts in for 60 Watts out. The switchers we employ, are chosen for high efficiency of course.
    All this to say, if a unit needs 600 milliWatts  to operate, that would be 500 mA at 1.2 Volts (NiMh) but only 400 mA at 1.5 Volts (lithium). And all this is complicated by the fact that the lithium starts out at 1.5 Volts and then gradually falls to 1 Volt or less before dying and the NiMh stays at 1.2 Volts until suddenly collapsing.
    Best Regards,

    Larry Fisher

  6. 20 hours ago, Blocktek said:

    Yes. I recorded tone with record run TC and checked the file for when the tone stops. On the NiMH, that was confirmed by the timer on the SRc.

    And I just tested a second Eneloop Pro fresh off the charger and got the same time, within a minute.

     

    Louis

    Perfect

  7. 18 hours ago, Blocktek said:

    A little late to the party, but I just tested 1x Energizer Lithium vs Eneloop Pro AA in my SMWB.

     

    Results:

    Eneloop Pro: 03:42:30

    Energizer Lithium: 05:39:00

    Just double checking: You ran the batteries down until the transmitter died?

    Best Regards,

    Larry Fisher

  8. 13 hours ago, seth said:

    So I made a Tip pin 2, Ring pin 3, sleeve pin 1 and one with out Ring pin 3(negative) and it sounded way better. less tubby, not sure why. I'd recommend opening one up and cutting off the connection at pin 3 connection. I know I've read this before. Just forget these things. I need to make my own note book when these things come up lol.

    The output on the IFBlue is two parallel headphone amps with the same signal (and polarity) on tip and ring. This will drive stereo headphones in a dual mono mode. Going into a balanced circuit using an XLR will give different results depending on the input of the camera or device, i.e., is it balanced and floating, balanced and center tapped, or unbalanced but just happens to use an XLR. Theoretically, the tip and ring signals should cancel out leaving you with no audio. Small differences in level from the headphone amps will give a small difference signal but not of good quality, i.e., your tubbiness.

    My general recommendation for any unknown device is to tie the IFBlue sleeve (ground) to pin 1 of the XLR , IFBlue tip to pin 2 and leave pin three of the XLR open. Then also try pin three of the XLR tied to pin 1 with a temporary jumper. Quite often there will be a big change in level. Use the higher level configuration. If there is little or no difference, then leave pin three open.

    Rarely, an older device from even a major manufacturer will make pin 3 of the input hot and pin 2 dead or grounded. If so, reverse all the pin 2 and pin 3 directions above.
    Best Regards,

    Larry Fisher

     

  9. [snip] ...but for now adding longer cable gives me higher mW !! 😂  it does not make sense, yet. [snip]

     

    The fact that minor cable length difference makes a power difference is a very strong indication that the measuring device is not a 50 Ohm load and is not terminating the cable properly, i.e., there are standing waves on the cable.

    Best Regards,

    Larry Fisher

     

     

  10. 40 minutes ago, EnotsMedia said:

    [snip] The case definitely feels flim flam but hasn’t shown signs of wear. [snip]

    Out of the thousands sold, we have only had to repair single digits of door, case or clip.

     

    Two possibilities:

    1. The casual users on set are incredibly careful with the sound department's equipment.

    2. The case is stronger than it looks.

    Your choice, since you know the your users well.

     

    Also low cost IFBlue clip, knob and door repair parts are available at Lectro.

    Best Regards,

    Larry Fisher

  11. 17 hours ago, EMP said:

    Hi Larry,


    Thanks for the explanation.

     

    I have a similar question about the second antenna contact in G3/G4 bodypack receivers (the one that’s connected to the TRS sleeve).

     

    To add a second SMA input, I removed the ring connecting the antenna contact to the AF Out (as sisal described above). However, the multimeter shows that the antenna contact is still shorted to the ground.

     

    Is it caused by the inductor as well?

    I think so.

    LEF

  12. https://www.instructables.com/Inductor-Color-Code-Guide/
     

    I read 7.5 uH 10% but I'm not that familiar with military markings. Anybody that is, chime in.

    At 216 MHz that inductor would have a reactance of 10k Ohms or effectively an open circuit for RF.  The 1 Ohm resistance you measured would be at audio frequencies.

     

    Those values pass the smell test. The inductor value is not critical. Any value from 2 to 8 uH will work. The 7.5 uH is little high in my judgement but that value would also work down at 72 MHz which may explain the higher value.

    Best Regards,

    Larry Fisher

  13. Your calculations are absolutely correct for 50 Ohms. Fifty Ohm values are typically used for RF levels since that is the most common impedance for RF devices and RF measurements. For audio levels, 600 Ohm levels were once the most common. Pro equipment still uses those values as a reference. That is what I did when I referred to 2 dBm, thinking of meter levels in a pro audio mixer or recorder. However, the most correct value for the Lectro IFB output is the 1 Volt into 50 Ohms specification. That is exact and has nothing to do with RF but is an average impedance value for most headphones that typically range between 32 and 80 Ohms.

    All this to say, the IFB will have the least self noise going into a line level input that has enough gain to match to low line levels of 0.1 to 0.3 Volts RMS.

    Best Regards,

    Larry Fisher

  14. On 4/28/2023 at 2:24 PM, jwill said:

    What cable are you using to get from IFBlue into camera, is it mic or line level?

     

    From IFBlue.com  

    Audio output:

    1V RMS into 50 ohms minimum

     

    Treat it as a consumer line level. It is a stout headphone level i.e.,+2 dBm.
    Best,
    LarryF

  15. The IFB systems (Blue or Lectro) have a moderately narrow modulation acceptance of 20 to 25 kHz. If used with a common 50 kHz modulation transmitter they will spatter on peaks.

    Best,

    Larry F

  16. Try :

    AT 1 to Lectro 1

    AT 4 to Lectro 3

    Lectro 2 to Lectro 4 

    If this has very low gain, then try adding

    AT3 to Lectro5

     

    https://www.lectrosonics.com/lectrosonics-microphone-wiring/uhf-transmitter-5-pin-input-jack-wiring.html

     

    The 4 Volts and current limiting from the Lectro should protect the mic in any hookup. The regulated Lectro 4 Volts at the mic is actually more voltage at the mic than provided by typical "5 Volt"  wiring through a load resistor.

    Let us know if any of this works.

    Best Regards,

    Larry Fisher

    p.s. Phase is flipped 180. You may need to correct for that if near other mics

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