A "Shock Box" for the Neurotic Icom 705 Owner

Executive Summary

Many thanks to Thomas, K4SWL, for posting this description of my IC-705 shock box in April 2022.  

Most of this blog entry comes from that original writing, but this blog entry supplements that and shares a few learnings I picked up along the way.

There's not much to summarize for you busy execs other than to say this provides a couple inexpensive options for hauling your IC-705 out in the wild. 😎  

There are three versions of the box, differing in lid and height. 

1) Rev.0 is a short, pretty version but not watertight.

2) Rev.1 is water-tight and uses the ammo box without modification, except to add the internal components.

3) Rev.2 is a shortened water-tight version of Rev. 1, that saves a couple inches of height.

Why a Shock Box?

Pictured above is the Shock Box Rev. 0., pretty but less functional, hence Revs 1 and 2. 

And pictured below is Shock Box Rev. 2.

Why not a padded bag or a cage?

Not to throw shade on a cage or a bag. But what you need depends on your use case.  

A frequent use case for me is hiking in the mountains of Colorado.  

The radio gets to its destination in some version of a backpack, is pulled out, balanced precariously on a slope, operated, and shoved back in the backpack.  

There is often wind and rain, and a rocky, gritty staticy (sic) dust.  There's frequent bright sun at 10,000 feet. There can be snow until mid-June. And if the radio tumbles in any direction, it's landing on rocks and sometimes rolling downhill.  

I can be a klutz, and those tumbles are induced by a human error, often involving an antenna or feedline, but can also include the error of bringing along a dog, or less desirably, another human.

Based on my use case, I need impact protection when the radio is in use, moisture and dust protection when in transit. Often I need waterproof base when the radio is sitting in muddy, wet or snowy conditions.  Carrying chairs and tables is a lot of extra weight, and it's not that easy to find a flat spot for them, so I'm usually on a pad with the radio on the ground.

So what I need:

1) isn't a cage that only transfers shock to the radio when it falls, and otherwise offers no protection to the radio;

2) isn't a bag that the radio lives in with heat transfer issues, that can get wet and retain moisture, or requires operating the radio outside the bag, negating any impact protection; and 

3) can provide good moisture, impact and dust protection when hiking.

We're off to Harbor Freight

As always, the journey began with a trip to Harbor Freight. I returned with the infamous six dollar (maybe eight bucks now) plastic ammo box.

Thinking about what to do with the box led to this literal back of the envelop sketch.  OK, that's not the original sketch, I had to make it (kinda) legible.

Looking at the picture you can see that:

1) there's a clear path for airflow around the radio.  Sure, it's passive, but is better than a radio wrapped in a bag like a burrito.

2) The radio is deeply recessed in the case, protecting from most anything but a direct impact on the front panel.  This placement also provides sun shading from most angles.

3) When the box is open, the radio is generally protected from dust and water except from the front, which is about as good as I can do and still punch the buttons.

4) And for me, most importantly, the radio rides on shock-absorbing pads.  If there is impact on the case, the plastic case deforms some, dissipating some energy, and the shock-absorbing pads dissipate a lot more energy to minimize the mechanical energy transferred to the radio.

With respect to shock, research had led me to Sorbothane, a commercial vibration damping material available in small lots on eBay, and to a Sorbothane applications engineer. 

The engineer recommended that a good way to protect electronics is to use a “box-in-a-box” concept where the equipment resides in an inner box with vibration dampers between the inner box and an outer box.

Sorbothane’s on-line calculators suggested that for the IC-705’s weight, some relatively small pads on each wall would be adequate.

So I started with the bottom 4 1/2 inches of the Harbor Freight ammo box, and added1/4 inch thick, 1 inch by 1 inch Sorbothane pads to the bottom and the two long sides of the box.

Then I added an aluminum plate to the inside side surfaces of the pads, and lined the plates with neoprene (see the drawing above and the picture below). 

The neoprene adds a bit of additional padding, but primarily lets the 705 be easily wedged into “the inner box” while putting a little bit of pressure on the pads. The manufacturer recommends a slight loading pressure on the pads for proper damping.

The radio is fastened into the box with an adjustable depth 1/4-20 threaded locking knob, positioned to put a little force on the back wall vibration pads when tightened down.  Purists will recognize that a blow to the screw knob will not be attenuated much in this configuration- and that's right.  But it's a low probability event I'll live with.  Or I'll find a rubber cover for the knob.  But I'm not that neurotic.

The Rev. 0 cover is made of aluminum angle stock and Lexan, and provides good protection for the front of the radio when not in use.  This configuration also makes the box much shorter than stock, what with having a flat top and no top handle, what with using only the bottom 4 1/4 inches of the ammo case bottom section.

It also looks cool, but as mentioned, it traps heat, so the cover has to come off during operation.  So it's not watertight.  But it was a good first shot at something to throw in the pack.

This led to Rev.1, using the same concepts in an unmodified HF ammo box using the same internal configuration. Nice, but pretty big, at least a couple inches deeper than needed unless you want internal battery storage, in which case you're done.  That lead to Rev 2, below.

Rev. 2 is what I use now. It uses a shortened ammo box made by cutting the box around the periphery just below the point where it bulges out toward the lid.  You can then slide the cut off top portion over the outside of the bottom portion (slide it up from the bottom), and then use a six dollar HF riveting kit to rivet the top portion and its attached lid back on.  Then you can seal the joint with silicone caulk or epoxy.  

I know this sounds a little bizarre but the taper of the box is such that the two portions are a near perfect fit, enabling the use of a shorter box but still using the water-tight gasketed lid as built.

Look closely at the picture, it might make more sense.  The silver spots around the top are the rivets the secure the cut-off top to the bottom portion.

Before you fasten the radio in the box, you need to attach extension cables for the functions you want to use while the radio is in the box.  You can see them below:

1) on the right side, the PowerPole cable for charging the internal battery or connecting an external battery;

2) the braided blue cable barely visible below the power cable is for the key;

3) on the left a cable for headphones - you can see a little headset drawn on that cable end with silver permanent marker to differentiate it from the not visible cable dongle for the mic.

There's even a gap for the idiot's guide to the 705 (a very necessary evil here).

You can see the box in use if you look back at the mountainside pic.

 

Compared to a cage or a bag:

1) I can leave the box on when operating.  This avoids field-handling errors, to which I am prone.  I simply remove the cover, and use cables out the front for things I want to change while operating, like the antenna, mic, key, battery power, headphones or paddles. 

2) If the internal battery needs to be changed in the field, the radio comes out quickly by removing the single 1/4-20 knob and screw. But the battery can be charged in the case with a USB or power plug cable, again avoiding handling.

3) The depth of the box protects the entire periphery of the radio front, much like the handles do for the sides of a cage. The radio remains enclosed/covered on all sides except the front. If you drop it, the radio is well protected except from something that sticks out of the ground enough to fit inside the periphery of the case.  Possible, but not very often. 

And I’ve used it in bright sun, snow and rain, with the outer lip of the box shielding the display from direct sun, snow and rain if the box is sensibly oriented.

4) Impact protection is really high other than for a direct frontal panel hit within the box. The plastic box takes the first hit, deforming a bit and transferring the rest of the energy to the vibration-damped inner box. Not worried about dropping the radio anymore.

5) The use of Sorbothane’s “box-in-a box” with vibration pads concept leaves a channel surrounding the radio to promote air flow and heat dissipation. For me this is much better than using the radio in a box cushioned with foam, which can block air flow and can trap moisture.

6) The box provides a handle, which the 705 really does need in the field.  It's barely shown in the pic of Rev. 0, poking its head above the top.  In this case it is that six inch length of one inch orange strap bolted to the case.  In the Rev. 1 and 2 configurations, the handle is just the standard installed handle on the lid of the box.

7) The footprint of the Harbor Freight box is just about a hand and glove fit in the bottom of most serious packs, making it easy to carry when backpacking.

On the downside, it’s a bit ugly, but it’s cheap and functional. 

The pics below show the front and sides of the three versions of the box.

Don't be scared by the shiny pronged thingy on the back of Rev. 0.  This is an adapter that lets the 705 be mounted on a chest carrier for pedestrian mobile use, and can be found in another blog entry.

Summing up. 

Do you need a cage or a box? Probably not.

Does it work well for me? Yes.

As always, I write about my experiences. These aren't my recommendations, just what I've done, provided in case (no pun) any of those ideas might resonate with you.

It's up to you do things safely.  In this case in particular, proper operation of the box requires getting the radio wedged into the box to get some compression on the vibration absorbing pads.  The radio won't fall out, it's screwed in, but there needs to be compression on the pads for proper operation of the Sorbothane dampers.

Have fun!

Scott ka9p/zf2sc