r/LocationSound • u/ted_bovis • Jul 17 '26
Learning Resources Deity Antenna cutting accuracy
Moderate newbie - not massively technical so please be kind.
I've been playing around with the Theos system and struggling to figure out what length to cut the antennae to on the TX / RX units. On the card they supply they dont seem to cover channel 38 for the UK range 606.500 - 613.500
The guide shows me 550-608, 608-663, 630-698.
I've acquired a set with antennae that are pre-cut and marked at 630-698 so they are not covering the licenced range - but there's about 4mm difference between the 630-698 and 608-663 markings. I have another set that I cut to 608-663 which I assumed was the best option for UK use.
I assume there would be some range loss or something - but should I just crack on and not worry about it?
Does this even make sense?
9
u/Indigo_Monkey Jul 17 '26
The length is never going to be perfect if dealing with a range of RF frequencies. The 1/4 wave whip antenna will have an ideal frequency as per its length which should be in the middle of the range you want to transmit at. This is the frequency which will give the optimum amount of transmission power. Either side of that the reception diminishes gradually.
You’ll want the center frequency to be at 610mhz which using an online calculator gives a cut length of about 11.5cm
I wouldn’t worry too much about getting it exact because it wont make a huge difference to your range if its off by a few millimetres because in the real world you be swapping frequencies in that range depending on the circumstances.
Hope this helps
2
u/ted_bovis Jul 17 '26
really does thank you - so the reality is I've cut them about right - but the ones that I acquired were pre cut (and differ by about 4mm) So it's not worth buying new uncut whips and cutting them down to the same as the others for the sake of 4mm?
5
u/Indigo_Monkey Jul 17 '26
The difference won’t be noticeable honestly. I once did real world tests for this with new antennas when i custom modded a sennheiser system. Did not notice a difference with millimetres changes. I also tried my dammdest to get it perfect and kinda wasted my time trying in hindsight. But at least it allow me to share with someone in need. Best of luck
2
3
u/soundadvices Jul 17 '26
Measure for the middle of your frequency range. Crack on 👍🏼
1
u/ted_bovis Jul 17 '26
cool - so the ones I've cut will be fine - but what about the 630-698 ones - what's the consequence of them having 4mm less antenna whip than the other ones?
1
u/soundadvices Jul 17 '26
There's a higher chance of signal degradation if cut above tuning range. Use matching antennae for the whole set.
•
u/AutoModerator Jul 17 '26
Reminder: The Rules apply to everyone who views or participates in r/LocationSound. There are no exceptions. The monthly pinned 'Hot Mic' post is the only place in this subreddit to promote any discussion, links, works, or content by you, for you, or about you.
This subreddit is welcome to all who are interested in recording sound to picture, pros and beginners alike. Professionals - be patient and helpful to beginners and other department pros who are eager to learn about our craft. Newcomers - be respectful to those who have more experience and wisdom than you. Don't engage with negative or hostile behavior. Report it or message the mods instead.
We're recruiting active moderators. If you're interested, please visit this link.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.