Lets talk RF
Let’s talk about RF systems (exciting weekend topic).
RF management is almost a dark art, predicting & managing invisible energy to capture vital signal transmissions. For beginners who look at this it can be a common question to ask “why do I have to spend £1000+ for boxes that just do what my whips already do for free”?
For a couple of years now I’ve been using an AudioWireless DADM226(mk1) being fed from a pair of lectrosonics SNA600a passive dipole. I found this pair of distro & dipole pickup pattern work wonders for my radio mics (lectrosonics SRb), as it both unified the input signals & greatly improving over the cross-talk issues you get by housing Rx next to each other on whips (something not really talked about).
Being able to remote the antenna up on a mast is a real important aspect also, as it effectively removes obstacles from bag-mounted solution (like kit & bodies) & gives spherical airspace around the receiving material, optimising point-to-point line of sight (this is especially useful for end-mounted boom Tx).
An important element that has become more prevalent in recent years, is signal filtering. The mk1 solution I used above had a band pass 470-715mhz filter applied to the inputs, which further reduced unwanted side-band harmonics, improving the efficiency of reception. In my setup, I have my out-going coms transmitters (Boom feeds & house mix) mounted directly to the pole with the receiving antenna. The filtering is especially important here, as placing Tx in close proximity to each other & Rx antenna, can create an amplified mush of harmonics. As my outgoing signals are in a band outside the distros band-pass filtering, my Rx have protection (70dB of protection with the DADM226).
In the last year, I decided to upgrade my RF system even further, by upgrading the distro to the new DADM226 mk2, which now has the option of adjustable band-pass filter programs (mines set to preset 16 563-640MHz). This pinches the filtering of my Rx signal even further towards my desired channel range, thus giving me even cleaner signals (you can also get a version with this setting fixed that’s more affordable, though I chose the adjustable one for future flexibility). The distro also has some additional quality-of-life updates, like the more bag-friendly shape (thinner & longer, fitting easily in the front of my OR32), & 6 power outputs over the originals 3, so all Rx fed from the 6 output pairs can be powered from the same unit, meaning I hit 1 switch to power up/down my entire radio rig.
Along with the DADM226 mk2, I also added a pair of audio wireless LPDA-A-WB active/passive fins. These were a new model in 2021 that (for my eyes) has a unique ability of being both active & passive fins (typically you’ll have one or the other). This meaning if you use the fins without power, they operate normally, but then can also be powered (by 12v carried over the BNC connection from the distro), turning them active & allowing for gain boosting & reduction (depending on your needs). Compared to Dipole antenna, which have a pickup pattern similar to that of a large (*mmmm)doughnut, LPDA fins (“Log Periodic Dipole Array”) are more directional, with side rejection of signals, with on-axis signals subject to passive gain of 6dB, which is can be a real boon in sculpting where you pull RF from & the distance available from it.
When getting this setup, I had the real blessing of taking guidance from Aldo Hakligil, a literal RF Yoda & mad scientist who created this kit. His expertise on RF management is 2nd to none & advised me on best working practices for cable-compensation using the active signal boost provided by the active fins, down the 6m of BNC I snake to my bag setup. These fins also have they’re own filters (470-700mhz, with -70dB) which further reduced unwanted signals at the very front of the chain, especially when paired with my distro filtering (2-stage filtering of RF) as it means any outer-band nastiness is totally eliminated!
The combination of the LPDA-A-WB & DADM226mk2 has given my whole system what feels like wings. In the last year that I’ve put it into use, I’ve had so very little problem pulling in the all important talent & boom signals, & the range I’ve been able to achieve with total stability has made me more & more flexible to the ever changing needs of location film making, for instance; over the last 2 days I’ve been stationed on the ground floor under the set on in a room on the first floor, & while range is often a metric radio systems are judged on, on this instance it’s stability through solid objects (concrete floor) that has won the day, with not a single moment of lost RF, while the AD was super happy that I didn’t need to be stuffed into an already busy set. I’ve experienced this a number of times now, where I’m stationed a few rooms away from talent, & have still had full RF confidence, especially in the context of using digital radios (I added a set of Audio Ltd A10 last year for my boom). Digital radio signals are notoriously inflexible & fallible to disruption, but this rig has been entirely up to the task, & I’ve found I rarely ever have to go outside of low-power mode (on the A10-Tx), even on Std mode (the new LR mode gives almost high-powered analogue like performance).
An interesting point I’ve found with this system after spending over £2k on it, is once I set it up & finalised my workflow, it literally went in my bag, & I’ve not thought about it once, it just works. For me it’s been an unsung hero in rig, & one that silently pays for itself many times over by just delivering consistent stable results.
If you’re new to the game, or are at the point where you’re planning to expand your rig & power up your RF system, I hope this will be useful user-case scenarios. I’d also strongly recommend Talking to Aldo over at Audio Wireless, as the man literally gave me a crash course in RF management that has served me very very well!
So until next time Hivemind, I wish you all clean spectrums!
