Rory Reshovsky

I use the exact same case, and it's the best solution I've ever found for AA batteries.

Agree with the others that lead-free solder is a pain to use. That being said, when I've been forced to use it (in college due to EHS requirements), I found that extremely liberal application of flux helped make it manageable.

The easy way to do this is find a suitable USB-C car charger, and use the circuit board from it. Despite car power being nominally 12V, it can actually vary within the same range you'd find from common location sound batteries. A good quality car charger will already have protections for over and under voltage, and if it supports USB PD, then it will have the communications interface for negotiating the higher voltages used in that spec. 

I do SMA mods as a service, and I occasionally get units in to repair/redo the mod that was attempted by someone else.

The 3 most likely causes I would guess for your issue are (from most likely to least):

1. Broken connection between SMA pin and RF board (thus no signal getting to antenna)
2. Short between RF out and case (all RF power getting dumped to ground)
3. Damage to components/PCB while mod was performed

If you can post a picture here we can possibly help you diagnose the issue.

Are there batteries currently in the slate? Pressure from the batteries pushing on the cover increases the resistance to open the slider. If you have left alkaline batteries in for too long, they could have leaked, causing the stuck slider.

Try applying inwards pressure at various points along the cover while attempting to slide the cover open, in case there's a particular spot that's binding. If you feel like you need to apply more force than you can easily with your hands, try sticking a piece of rough tape on the slider to increase your grip. If even that does not work, use a strip of tape hanging past the edge of the slider. Use one hand to push the tape into the slider so the adhesive stays attached, and pull on the "tab" of tape hanging over the edge.

One tactic could be to run the audio cables through metal conduit, either parallel to or inside of the PVC pipe (electrical code allowing). If the conduit is bonded to ground, it should form an effective shield against interference. Others with more experience may have more to say on how well this would (or wouldn't) work.

You can achieve a similar outcome by shortening the cable, and heatshrinking some some stiff wire (armature wire is ideal) alongside the lav cable, and all the way down to the connector.

This type of sleeving is also often used to protect machining cutting tools during shipping and storage. This might help broaden your search term keywords and find more suppliers.

Here's an example:

https://www.huot.com/products/product-category/sleeve-webbing/

While not the exact same cable, Mogami makes some very small and extremely flexible cables. W2444 seems to be their smallest, with a 1mm diameter, and many other models in increasing sizes. Markertek sells it by the foot if you want to try it out.

On 1/14/2020 at 3:33 PM, IronFilm said:

I wonder if the wireless video systems that FPV drone racers use would be a smart idea? As like us, they don't care about perfect picture quality but range and robustness is instead their highest priority (oh, and small size and battery powered!). 

I've looked into this, and most of these inexpensive systems are composite PAL, so you'd need to convert HDMI or SDI to composite PAL in order for it to work. If you want to use your normal production monitor on the receiving end (instead of a purpose-built FPV monitor with a built-in receiver), you might also need another converter if your monitor can't accept the composite signal natively. Many of these systems operate on 2.4 or 5.8 GHz, so you may experience interference if a Teradek (or similar) is in use in the area, or even just a lot of WiFi. I almost went this route, but it just seemed like I would need so many pieces (and points of failure) to get it working, and that the end result would likely be somewhat clunky.

Amimon (the company that provides the chipsets/underlying tech to Teradek, Paralinx, Vaxis, Arri, etc, and was recently acquired by Teradek) makes an HD wireless video system called the Connex that's targeted at FPV use, but does a fantastic job for general purpose video as well. Quality/range is on par with Teradek (it's the same chips inside), and I can easily get 1000 feet with standard antennas on my set. With a panel antenna, you can go 3-5k feet. Unlike a Teradek, the Connex won't transmit the embedded audio, but that doesn't sound like a problem for this application. The whole system is HDMI-only, but most monitors will internally cross-convert, and there are lots of compact converters in case you can't find an HDMI loop-out. Power-wise, the transmitter uses uncommon connectors, but if you get a DTAP cable, a LEMO cable, and a wall-wart, you should be set for most circumstances. The receiver just has a standard barrel jack. Both transmitter and receiver have very wide voltage ranges, since it's meant for RC use. The transmitters are tiny, so it should be unobtrusive wherever you stick it. I'm not sure how the receiver does with RF spray (mostly use my system for aerial/gimbal work), but now that I'm curious I'll definitely test it out. Sets can be had for ~1k used on eBay, so a pretty good value for the performance when you compare to "film industry" brands. There have been several versions, so the best combination currently is a Connex Mini Air Unit (the one with SMA connectors), and Connex (not mini) Ground Unit (the one with 5 antennas), more recently marketed as the Connex Fusion Ground Unit. 

It's just a cheap transformer from an old RadioShack Hi-Z to Lo-Z adapter (basically a really cheap DI box). Check the SKP100 manual for the pinout on the unbalanced side. 

I put the transformer between the SKP100 and the MZA14. According to the manual, the SKP100 is actually an unbalanced input, so by using the transformer like how you'd use a direct box I'm taking the balanced out from the MZA14 into the unbalanced input of the SKP100. This isolates the two devices, and seems to have solved my hiss problem.

The noise floor is still noticeable higher than with a cable, though. 

51 minutes ago, chrismedr said:

 

Use a cabled boom or if that is not possible save up for a proper wireless system for wireless boom?

 

sorry if that sounds harsh, but compromising your primary source of audio with unreliable and low quality components just seems penny wise and pound foolish to me. unless you're doing this as a hobby of course, then anything is fair game  : )

 

 

I agree with this. Even with my transformer workaround making this system function, I'd never trust it for anything where I cared about the end result. I'm actually planning on selling my MZA14 and SKP100 in favor of an SD MP-1 going into an SK100, or an SKP300.

I have had this exact same issue with an MZA14 going into an SKP100. This probably isn't the "proper" solution, but I got my setup working acceptably well by putting a transformer between the MZA14 and the SKP100. 

One thing to note, the BaoFeng radios are handheld HAM transmitters, so while they have the capability to transmit on "public" frequencies (GMRS or FRS), they are not technically type-accepted to be used as such. You'd definitely have to reprogram them, as they're shipped from the factory with random test frequencies, many of which are illegal to transmit on (public safety, etc). 

That being said, they're great value for the money (I personally have 16 of the BF-888s), and while they're not nearly as durable as a Motorola, I also don't have to worry about people trashing them, because they cost me about $10 each. As Spectreman mentioned, most other (non-Chinese) radios will sound much better, but for the money, I don't feel they can be beat.

A theatre at a school I attended switched to the Switchcraft connectors after all of the stock ones broke. They're absolutely amazing (albeit costly). The only time I ever had to replace one of the Switchcrafts was after an actor landed directly on one during a stunt.