Sharkfins - Any Difference?

[ptalsky]

All,

Looking to pick up a pair of sharkfins, and was wondering if there was any real difference, other than price and on some models, frequency block.  For example, PSC sells a 4xx-9xx frequency model that is significantly less than the Lectro version.

Thanks in advance!

Phil

[RPSharman]

All the specs are the same.  As a utility/boom guy, I worked with mixers with almost all different kinds of antennae and cable configuration with varied success.  As a mixer, I choose to raise a pair of the PSC sharkfins on flex arms above my cart with an expanding painter's pole.  I use 15' of inexpensive, thin, 50ohm RG58 with no barrels in line, and have had very good luck with wireless reception (knock on wood), easily as good if not better than any other configuration I previously worked with.

[wolf]

of course there are diffrences, our Radio mikes are so ggoo nowadays that yu can use the manufacturer provided wips and get away with it for 98% of the work... but then...

LOG PERIODIC (FLAT PANEL) ANTENNA

WSV Green Flat Panel

This is a special kind of Yagi.  A Yagi has narrow bandwidth and high gain. This has broad bandwidth but less gain.  It is not quite as directional as a Yagi.  Think of it as a 3 element Yagi.  These are popular antennae because they cover channels 14-69.  In urban areas where you may be close to a very strong TV station on adjacent frequencies, these broad frequency antennae may overload the front end of your receiver.  A Yagi, cut to the one frequency you use, will act as a filter and reduce this problem.

LOG PERIODICS (SHARKFINS) COMPARED

We recommend for general use the WSV green flat panel Antenna. This is a high gain flat log periodic antenna. All antennae are good at short range. Where they differ is in the extreme end of range. In a bad multipath environment at short range, any directional antenna is better than a non-directional one. The omni rubber ducks are non-directional or omni directional. So if you can, use a directional antenna.

The gray CIT ultra has a little more gain than the other three we tested: WSV aluminum, Lectrosonics flat panel, PSC flat panel and WSV green flat panel. 

In normal transmitting distances with a decent signal, there is no difference between these antennas. At low signal strength there are very subtle but discernible differences between the antennae and between cable types used. 50W black Belden cable is preferred. Generally, the CIT (gray) antenna is a little more sensitive to low level signals at high and low frequencies. This shows up on the DX-404 tuner as one or two additional LEDs lighting up. The WSV (green) antenna seems a little more sensitive to reflections from objects within 3 ft. of antenna. The Lectrosonics (black) and WSV (green) seem to be very similar otherwise.

What this means in practical terms is: if you’re receiving a small transmitter at the end of a 100 yard football field, the CIT antenna would be good for 100 yards, whereas the others will be good for 98 yards.

Again, this is splitting hairs at the extreme far end of the receiving range. The new DX-404 tuner seems to switch antennae without any color phase shifts in the picture.

Relative position (where you put the antenna) is much more important than the exact direction you point it or the brand of antenna.  So move your antennae 6" to left or right or up and down for best pictures.  This demonstrates the radical effect multipath has on the signal.  The reason the picture is bad 6" away from the original position is only multipath.  So when you see a picture get bad and then good when one end of the transmission chain is moving, you are observing the different patterns of multipath.  Therefore you should continuously experiment with better positions.

The CIT antenna is very bad below channel 14. Our WSV Log Periodic is not as sensitive to accurate pointing.  It has a wider pattern. With low signal strength use the side lobes (30° off center) rather than on axis.  CIT is very sensitive to horizontal - vertical position.  For best results, it has to be perfectly parallel (the same spatial plane) with the modulator’s antenna, especially at the higher channels. (This is the price you pay for the high gain.)  WSV Log Periodic has slightly less gain than others but is much easier to point.  Antennae in order of gain: CIT Ultra Antenna, Lectrosonics, PSC, WSV. Remember to experiment with antennae positions all the time.  The best solution is four antennae spaced by 3 ft. for the diversity receiver of course.

Look at the artwork below and think a little. If the transmitter is vertical, the receiver also has to be vertical. Note the difference in vertical or horizontal radiation pattern. This is called phase of a transmitter signal.

YAGI OR FLAT PANEL FOR RECEPTION

· A Yagi is an antenna that looks like your rooftop TV antenna.  Mount antenna on "C" (Century) stand up high (7 ft.) for safety sake.  Reception is better the higher the antenna. Use our new stand extender (5ft).

Single channel Yagis have several advantages that may be critical in difficult situations:

· Selectivity:  Some are tuned only for one channel only some for a few.  The antenna will reject adjacent broadcast channels that  are usually much stronger than low powered modulators.

· Directivity:  Front-to-back ratio are as high as 20 dB.  The angle of acceptance of a signal is very narrow. This is especially noticeable at long range.  Experiment with very small directional increments when pointing the Yagi.  Hold antenna on central rod in rear if necessary. At short range directivity goes away but you can optimize reflecting signals (multipath) by rotating antenna to null out reflections.

· The general TV type Yagi's have 9 dB gain forward and some rejection of signals from the rear.

· Make sure you mount it vertically polarized (opposite from what you see on most rooftops), matching modulators antenna orientation.

check  www.wolfvid.com  for lots more educatinal stuff....  wolf

[Philip Perkins]

You can build a very good set of sharkfins yourself w/ parts from Ramsay and etc.

Philip Perkins

[Sergio Sanmiguel]

You can build a very good set of sharkfins yourself w/ parts from Ramsay and etc.

Philip Perkins

Or you can buy the cheaper ones from Kent Electronics...

[Philip Perkins]

Or you can buy the cheaper ones from Kent Electronics...

Sorry--right, couldn't remember Kent's name.  In any case they sell about the same thing,

so if yr handy you can make some fins that are slightly less rugged than PSC and etc,

but WAY cheaper.  The Ramsay ones I got (now several years ago) had the SNA connectors

already attached.

Philip Perkins

[Izen Ears]

  I just switched to the PSC sharkfins + the 1x8 antenna splitter and my reception problems went away.  (And boy was I having a ton of them with my 411s!)

  But now I seem to hear more noise, I'd call it 'hiss' when I turn up the gain.  I'm using 50' PSC BNC cables, but for testing I tried 4' and 10', then 100' and the hiss was the same on all of them.  The wireless boom has less hiss than say the Sanken COS-11s, but it's still there.  My gain structure is using the 400 txs at 12 o'clock and the 411 rxs at -05db to -15db, with the input set to mic on the cooper board with the gain knob all the way down.

  Is it possible the antenna splitter/sharkfin system is adding some component noise or something?

  I had SO many problems with the regular antennas (I used to throw out a 'tree' with 6 receivers and a 100' 8-way XLR but I still got tons of rf problems) I'd rather have hiss than the dropouts and rf hits I was having before.

  Dan

[FSBELLA]

  I just switched to the PSC sharkfins + the 1x8 antenna splitter and my reception problems went away.  (And boy was I having a ton of them with my 411s!)

  But now I seem to hear more noise, I'd call it 'hiss' when I turn up the gain.  I'm using 50' PSC BNC cables, but for testing I tried 4' and 10', then 100' and the hiss was the same on all of them.  The wireless boom has less hiss than say the Sanken COS-11s, but it's still there.  My gain structure is using the 400 txs at 12 o'clock and the 411 rxs at -05db to -15db, with the input set to mic on the cooper board with the gain knob all the way down.

  Is it possible the antenna splitter/sharkfin system is adding some component noise or something?

  I had SO many problems with the regular antennas (I used to throw out a 'tree' with 6 receivers and a 100' 8-way XLR but I still got tons of rf problems) I'd rather have hiss than the dropouts and rf hits I was having before.

  Dan

Izen,

try the RG8 - 50ohm low loss cables with a cable run of 25' max (15') is good.

PSC sharkfins are fine, just for kicks eliminate the 1x8 splitter and use the shorter

rf cables.

also, try putting the tx's at 10 & 11:00 clock and the rcvrs at -20 then even -25db

you might have to bring up the cooper trim or gain up a little, but the " hiss" should go away.

gd luck

[FSBELLA]

Izen,

also there has been posts here before about using the A side of your six pack, venue, lectro tray. with a sharkfin and the B side w/the lectro dipole antenna

one side omni, one side directional.

what are you using btw? 

[Izen Ears]

Izen,

try the RG8 - 50ohm low loss cables with a cable run of 25' max (15') is good.

PSC sharkfins are fine, just for kicks eliminate the 1x8 splitter and use the shorter

rf cables.

also, try putting the tx's at 10 & 11:00 clock and the rcvrs at -20 then even -25db

you might have to bring up the cooper trim or gain up a little, but the " hiss" should go away.

gd luck

  Yeah I did switch between the RG8 and the regular PSC stuff, it didn't seem to make any difference with the hiss nor the reception.  I didn't try eliminating the splitter since I got 5 receivers but I'll try it!  I did play around with the gains on line and mic, moving the rxs gains up and down, didn't seem to make a diff.

  Yeah I was just wondering if the splitter/sharkfins could possibly be adding that hiss.  Maybe I'm just doing quieter scenes and noticing something that was always there.

  Dan

[FSBELLA]

could be, have you had your cooper serviced or cleaned lately? sanken are bullet proof usually, are of them hissy. try to do a process of elimination with them

also,

what are the rcvrs in 6 pack multi tray etc??

[bcopenhagen]

....In any case they sell about the same thing,

....The Ramsay ones I got (now several years ago) had the SNA connectors

already attached.

Philip Perkins

Great info, guys.  I breezed thru the Ramsey antenna manual...it notes that the antenna designer's call sign appears on the bottom of the antenna:  WA5VJB , which happens to be the call sign (and website address) of.....Kent Electronics.

So they really are the same thing.

You pay a bit more to Ramsey, but, as Philip noted, it does include the SMA connector.

One other thought for Phil's original post:  the more expensive Shure antennas have active electronics which allow for switching between 0 and +10dB of gain.  In typical circumstances, the +10dB can actually be detrimental because it picks up more unwanted signals within the broad freq range of the antenna.

Though after quite a bit of comparison, the mixer I work with frequently decided he liked the Shure antennas (at 0dB gain) better than the Zaxcom sharkfins.

As far as confining the antennas to a freq block, that will refine your reception to just the range of your Tx.  But, obviously, it will prevent you from using those antennas with other wireless systems outside that block range.  The wider freq range 4xx-9xx provides some flexibility for using those antennas with additional rented or purchased radios in the future.

-Brian

[Guest afewmoreyears]

Many thoughts on this, but IMHO,

  I guess you might HAVE to use a specialized antenna in a few situations, but as I already posted on another thread,  run mic line and NOT antenna cable, RG8 or any other cable...

  It is a fundamental fact that putting the units closer is better than keeping them way back and trying to suck up signal with shark fins Etc.

  I have never had better luck with antennas......  move your units closer....

[Philip Perkins]

Many thoughts on this, but IMHO,

  I guess you might HAVE to use a specialized antenna in a few situations, but as I already posted on another thread,  run mic line and NOT antenna cable, RG8 or any other cable...

  It is a fundamental fact that putting the units closer is better than keeping them way back and trying to suck up signal with shark fins Etc.

  I have never had better luck with antennas......  move your units closer....

We went to some considerable trouble to make the RX rack removeable from the cart so that if I'm stuck far from the set the whole enchilada can be remoted to close to the action (w/the sharkfins) w/ line level feeds run back to me.  This has worked very well, if also being a bit more work for moves.

Philip Perkins

[wolf]

here the Ramsey antennae at an obscene markup for a cable and  breakaway mount. Sharman is wrong, there are differences between antennae and they are noticeable, but it takes careful testing. They differences are relevant when you get into trouble... usually that is a panic moment at work and conclusions drawn there are not reliable. Testing is something done away from the pressures of set work!  Testing antennae requires patience and careful blind comparisons of alike  gadgets.  Fancy instrumentation is not necessary just a calm mind and clean tools.  Conclusion:  Best is always a Yagi cut to your freq. ( I know maybe two mixers who practice what I preach)  The flat panels are similar but testing  with video shows differences more than with audio. Its a fragile signal.

Also for wide band reception the Helix has many advantages, someone in Herndon Virginia sells them commercially, of course they are too big to be practical for most run around film use.

here our answer:

http://wolfvid.com/datasheets/Antenna_UHF_flat_panel.pdf

SHARKFIN LOG PERIODIC ANTENNA FOR TV and FM audio RECEPTION    10dB GAIN

This antenna will do more than anything else to improve your video / audio reception.  Reduces double images and rolling pictures.  This broadband antenna http://en.wikipedia.org/wiki/Log_periodic_antenna is tuned for 400-1000 MHz or TV channels 14-69. The high gain extends the usable range of transmitters.  Highly recommended for good results even at short range where it reduces flicker.  Reduces multipath http://en.wikipedia.org/wiki/Multipath (out of phase signals that cancel the direct signal) and rejects signals from the side and back.  Beam width is 50º Horizontal and 90º vertical (with antenna mounted for vertical polarization).  It fits easily into a small 1500 Pelican case or the front pocket of our Sony 1041 tuner bag.  50W low loss cable with female BNC connector. This solid professional antenna comes with a 5/8" baby spud mount. Forward gain 10dbi for channels 14-69, front to back ratio 20dB.  Dimensions: 14 1/2” x 9-1/2” x 2”.  For cables up to 50 feet use RG8X a low loss 50 ohm cable. http://en.wikipedia.org/wiki/Coaxial_cable

Price:  $ 175.00  call  wolf  310  822-4973

if you really want to inform yourself on some of this stuff with lots of practical examples read this

http://www.wolfvid.com/datasheets/!MODULUS_X_OPERATORS_MANUAL_CLICKBOOK.pdf

lemme know if its of use ( there is a difference between pontificating and feedback)

wolf (smugly) from Marina Del Rey