Recommend paddle antenna for SRas

[studiomprd]

" a coat hanger will probably do the job "

... though I have found paper-clips, unfolded, usually have a better SWR

[Boomboom]

If you're wearing a bridge or braces, I heard you can run a short coax there... When you smile, you even have an additionnal gain of around 2-3dB ...

[LarryF]

And make everyone around you feel 3dB better too.

LEF

If you're wearing a bridge or braces, I heard you can run a short coax there... When you smile, you even have an additionnal gain of around 2-3dB ...

[taylormadeaudio]

I think you should not read with any liquid in your mouth Tom. You keep doing spit takes. That can't be good for the gear.;~)

CrewC

Yeah Crew,

Fortunately, I wasn't sitting in front of my gear... just having coffee and browsing via iPhone... but yeah, one really never knows when someone like Larry will strike... coming from someone who is usually on the dealing end of that equation, I guess it would only be karmic for me to get a dose once in a while. In any case, it was a nice read and great start to my morning (had to go visit the CPA... joy of joys)

~tt

[Marc Wielage]

I am looking to buy a paddle antenna to get better range out of my Lectros in certain situations where I can't be close enough to the talent. I would like to get one antenna which I would connect to one SMA connector on each receiver. I know another mixer who uses a skeleton Lectro sharkfin like this and is very happy with it. I've read all the threads I found about shark fin/paddle antennas but I still don't feel like I know much about the subject (passive or active antenna? splitter? amp? what?).

I would also recommend Lectro's excellent "Wireless Microphone Systems" technical paper, which goes into a lot of detail about different antennas, causes of interference, cable issues, harmonic distortion, and other issues:

http://www.lectrosonics.com/Downloads/wireless-guide.html

Similar sharkfins are available from several different companies (including PSC), and as long as they can handle the same frequency range, you should have no issues. I agree, the "skeleton" ALP-620 and ALP-650 are good at avoiding wind problems. We had some bad winds this past weekend here in LA, and I was constantly having to reach up and tweak my own log-periodic antennas back to the right position -- for 6 people in a van. Not a great environment for wireless, but 30 feet away, it worked fine.

[David Lascelles]

I have just invested in a venue kit with ALP650 antennas. Most of the time they will be fixed to my sound cart. Do the antennas work in passive mode if I turn the power off in the venue or do they need to be powered all the time? The cable runs will be only 2 meters so most of the time using the amplifiers will be overkill.

[graham]

I have just invested in a venue kit with ALP650 antennas. Most of the time they will be fixed to my sound cart. Do the antennas work in passive mode if I turn the power off in the venue or do they need to be powered all the time? The cable runs will be only 2 meters so most of the time using the amplifiers will be overkill.

They will not operate as passive. Call Lectro tech support. I forgot who I dealt with but he made a few 12db attenuator jumpers for me... for free. Lectro customer service wins again

[David Lascelles]

Thanks. Is there any disadvantages to using them active on short cable runs of 2 meters.

[taylormadeaudio]

Thanks. Is there any disadvantages to using them active on short cable runs of 2 meters.

You're gonna need to do some more research -- the Lectro site has a wealth of info available... pay particularly close attention to the areas regarding splitting, cable distances, and attenuation. You might have to do a little bit of math, but the info is all there. Active antennas can work splendidly with shorter cables, but that's gonna depend on how many rx's you're using, and how many passive splits you have in the equation, etc.

As to your particular setup, I'm not familiar enough with the Venue system to comment much further, but between the Lectro website and the help available from guys like Larry Fisher, you should be alright.

~tt

[studiomprd]

" any disadvantages to using them active on short cable runs "

yes...

could be ...

see reply #14, too

[studiomprd]

" any disadvantages to using them active on short cable runs "

yes...

could be ...

see reply #14, too

Some folks prefer the versatility of a multi-function antenna

[Audio Daddyo]

I have a Lectro ALP 620 shark fin and a Lectro SNA 600 dipole. I would like to use both the shark fin and dipole with 4 Lectro 411s. The blocks are bl 21, bl 25 and 2 - bl 26s. The Shark fin I believe is not an issue but will I be able to use the one dipole for all 3 blocks (4 receivers). Can I choose a center frequency on the tunable dipole that will work well for all 3 blocks (21,25,26)?

I also have a question regarding calculating loss. If I am using a 4 way splitter (Lectro ZFSC41) and decide to use only 2 receivers how does that impact the calculated loss of the splitter if it does at all. Will it be less? The rated loss of the splitter is 6dB but does that assume 4 receivers connected? So does the number of receivers connected impact the losses on the splitter?

Thanks,

Andy

[LarryF]

Hi Andy,

That is a 150 MHz spread (21-26) or 125 MHz if you use the middle of the blocks. That is more than the dipole will handle effectively. It will still be better than a coat hanger. If you don't need much range, however, it will work. The splitter loss is constant whether you have 1 or 4 receivers hooked up. The splitter is designed to isolate the signals so one output is not affected by what is or is not, hooked up to another output.

Best,

Larry F

Lectro

[Audio Daddyo]

Thanks Larry I appreciate the quick response. The situation I am in is that I will be following 4 bicyclists that will be wired up and I will be in a follow van. I plan to have all 4 of my receivers connected to a shark fin and a dipole mounted on the roof rack. I am hoping the shark fin will work for when we are directly behind or in front of them and the dipole when we pull up along side of them. So when the dipole is needed we should be pretty close. I hope that the the UFM50 amps that I ordered will get to me in time for my shoot on Tuesday.

Thanks,

Andy

[Audio Daddyo]

Larry,

If I choose frequencies at the top of block 21 and the bottom of block 26 that would decrease the spread to about 100 MHz. Is that significant amount for a dipole?

Andy

[LarryF]

Hi Andy,

That will help substantially. Also, the gain on LPDA's is not real high and therefore they are not that directional. They have good response 90 degrees to the side. The only deep nulls are behind the paddle and directly above the paddle. See this plot on page 4:

http://www.lectroson...alpseriestd.pdf

Note that at 90 degrees horizontal you are down 6 dB from the front gain and therefore only down 3 dB from a dipole. Since you will be next to the riders when at 90 degrees, you will have signal to throw away.

LPDA's are never high gain for their size and therefore not highly directional. Their claim to usability is their wide bandwidth as you are discovering.

Best Regards,

Larrry F

Lectro

Larry,

If I choose frequencies at the top of block 21 and the bottom of block 26 that would decrease the spread to about 100 MHz. Is that significant amount for a dipole?

Andy

[Audio Daddyo]

Thanks again Larry. Amazing to have access to you on the weekend and a holiday no less.

Now go back to eating your matzah! or is it chocolate eggs! or maybe chocolate covered matzah!

Andy

[LarryF]

Chocolate covered blueberries. It's a rough life.

LEF

Thanks again Larry. Amazing to have access to you on the weekend and a holiday no less.

Now go back to eating your matzah! or is it chocolate eggs! or maybe chocolate covered matzah!

Andy

[Audio Daddyo]

Is it correct to say that since I am using a wide spread (over 50 MHz) setup I should be going with the Lectro UFM 230 amp over the UFM 50? Is there a big downside to going to the UFM 230 if all things equal.

Since I won't have time to make all the BNCs I need for my shoot this week can I plug the UFM amp directly into the splitter? This would be short term solution.

Thanks,

Andy

[LarryF]

UFM230 will be necessary for the spread. Though the 50 MHz is my preferred unit, we are not hearing of any field problems with the wide band amp. It is a very tough amp. Directly in is fine. Talk about low cable loss.

Best,

Larry F

Lectro

[studiomprd]

" I am hoping the shark fin will work for when we are directly behind or in front of them and the dipole when we pull up along side of them. "

Once again we are trying to mix theory and practicality, an engage in a fight over the laws of physics at the same time...

Actually, both aerials will be working all of the time. Larry and others have discussed this stuff frequently...

I'm with Larry in preferring higher Q whenever possible (I also prefer Yagi aerials!), but lots of stuff ends up working, even coat hangers, though I prefer paper clips!

[Audio Daddyo]

UFM230 will be necessary for the spread. Though the 50 MHz is my preferred unit, we are not hearing of any field problems with the wide band amp. It is a very tough amp. Directly in is fine. Talk about low cable loss.

Best,

Larry F

Lectro

Thanks again Larry. You deserve another Chocolate Covered Blueberry or ten.

[Bill Ruck]

There is too much mis-information out there regarding antennas for wireless microphones.

First, all radio systems must follow the same laws of physics. There is no difference beween land-mobile communications, point-to-point communications, and wireless microphones (or for wireless in-ear monitors).

Second, always keep in mind that your RF neighbors with any UHF system are very high powered TV stations. Your puny 50 mW transmitter can't compete with 100,000 Watts of RF 6 MHz away.

For that reason, unless you really need very long cable lengths and your are shielded from TV transmitters by being inside a building, stay away from amplified systems. Especially wide band amplified systems. Even Lectrosonics designs (which are the best) can be overloaded.

I've found that antenna sold in the wireless microphone world are unbelieveably overpriced. Compare any design to the WA5VJB 400-1000 MHz log periodic

http://www.wa5vjb.com/pcb-pdfs/LogPerio400.pdf

at $25.

This is the same antenna that Ramsey electronics sells at a higher price.

Since UHF wireless microphones work in the exact same frequency band as UHF TV, any UHF TV antenna also works just fine.

This is another example that I've often used in fixed applications

http://www.mcmelectronics.com/product/ANTENNAS-DIRECT-DB2-/30-2065

MCM price is $41.99.

So why pay hundreds of dollars for an antenna?

Bill Ruck

[taylormadeaudio]

There is too much mis-information out there regarding antennas for wireless microphones.

Agreed... without the proper research, one can actually wind up wasting a ton of $ and have a system that actually performs worse that what they had prior...

So why pay hundreds of dollars for an antenna?

Bill Ruck

There are many situations that call for amplified antennas -- most of which have been discussed ad nauseam here and other places. Yes, long antenna cable runs -- and/or multiple splits feeding multiple rx's are the two biggest reasons.

Thinking that better performance is guaranteed simply by throwing a bunch of $ into an existing system is flawed thinking. Producers have done this for years -- they're not alone.

That said, the amplified antennas that are out on the market today definitely serve a purpose -- I've experienced first hand just how valuable they can be when implemented correctly. You don't show up for a simple kitchen remodel with a wrecking ball and 50-ton crane...

I'll skip the rest of the analogy

~tt