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Zaxcom antenna length


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What is the proper antenna length for Zaxcom block 21 and 26 transmitters and receivers? The manual says 4.48" (for block 21) but I received a Sam Woo Electronics cutting chart with some Zaxcom antennas that have very different guidelines. Also, the Sam Woo guide has very different lengths for transmitter vs receiver lengths. I would normally go off the manual, of course, but I was told by someone at Zaxcom that the Sam Woo chart is slightly more accurate. However, the two charts I have show nearly half an inch difference at each frequency. For example, one chart shows 600mhz should be 4.5" while the other chart shows 5".

Could someone who actually knows the proper length shed some light on this before I either start chopping my antennas or spend a couple hundred bucks ordering all new antennas?




Production Sound Mixing for TV, Films, and Commercials

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I find the numbers in the Zaxcom transmitter manuals to be suspect. I haven't run the actual computations, however.

One important thing is to figure the length from the top of the metal collar of the connector to the tip of the antenna wire. However, it's often not easy to tell where the top of the metal collar ends as it's usually covered by a vinyl boot that extends further with a tapered strain relief.

On my Zaxcom block 21 wireless, the receiver antennas are about 4-7/8" and the transmitter antenna is maybe 1/16" shorter than that, but I'm not certain exactly where the top of the metal collars are -- so these measurements are based on educated guesses.

Remember, you can always cut something shorter, but not longer, so I'd start at maybe 4-7/8" (or even 5" if you prefer).

Here's a comment from the Zaxcom transmitter manual which might help you rest easier:

"NOTE: Antenna length is measured from the base of the whip, where it is attached to the connector. The length of the antenna varies with the frequency block. The actual length of the antenna is not as critical as it might appear in the table. The antenna‟s usage bandwidth is +/- 50 MHz from the center frequency, so it is acceptable to use an antenna from an adjacent block above or below the operating frequency."

So, since Zaxcom's block 21 is 36mHz wide (536mHz to 572mHz), you should be fine.

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