Experiences and Ideas - Building a small form PC for dedicated Flex use as part of a new shack design

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I am currently building a new house after buying some land last year to move us further away from Christchurch which is experiencing a shift in populous after the earthquakes.

One of the fun challenges of that is I get a new shack and new antennas/towers. So I have been working towards building a modern shack that will sustain me over the coming years. 

My main interests are DXing at HF, VHF-SHF, Moonbounce and contesting and the remote location we bought suits all that.

Building a new house and shack is an interesting in that you get a chance to really start from the ground up. Normally you don't get to choose the boundary of the house, it's orientation and location of rooms etc. And that combined with where I can site the shack and new towers is really fun!

As part of the new shack layout I decided that I wanted to ensure that I can provide racked space for amps with vented air into the roof space to keep my shack cool in summer ... its can get warm out on the Canterbury plains and we have had some hot, dry summers due to El Nino.

I also decided that I want to minimise cabling etc and have been looking to IP radio connections, antenna switching, rotators etc as much as possible and bury network cables out to the towers etc.

As part of the new strategy I also decided to look at the layout of the desks and station positions. My room is big enough for 2 larger positions and at a squeeze, 3 positions for contests. Plus I have the ability to run an operating position in the workshop on the garage and an external position in my shipping container room that currently is used on site as a shack.

Thinking about these new positions I decided on 2 x Flex 6500's .. one for HF/VHF DX and one for HF/EME. As part of the new shack I decided on reducing space for peripheral devices. For example I have bought a Wavenode system and will run this with remote mounted sensors - this will allow integration into Flex and also means that a PC and screen can be used at each op position for monitoring.   To drive all this I also wanted to reduce PC space. Normally I have been using simple desktop PC's but the fans drive me mad and in the middle of the night during EME skeds the less noise the better.

To fit in with the reduced space reduce noise concept I started looking around at PC options but wasn't finding much in a reasonable price bracket. Intel NUC type boxes are great but they are extremely expensive in NZ but then by chance I stumbled across an article by lee W9OY on this experiences with fanless PC's.

So with this in mind I spent some time researching these devices and set out to find myself a new PC or 3!

For those who are not familiar with them, these PC's are usually small form factor (SFF) cased units that do not have fans for the CPU but rely on conduction cooling to the case. They also normally also rely on external 12V supplies and use low power components so these don't need a huge PSU. Of course this comes at a trade off. Size is tight so usually uses small 2.5" drives and SODIMM laptop memory. But I can say this does not come at a reduction in interfaces, my fanless PC described below has 8 USB slots!  These device are usually lower power spec machines too so usually rely on mobile chip sets and processors similar to those found in laptops.

Looking at the market for these fanless PC's you can find 100's of them in all sorts of specs, so how do you choose. I broadly set out the specs as:

- Needs to be Windows 10 capable
- Minimum of an i5 processor and at least 2 GHz or better
- reasonably later chipset version - broadwell or better 
- 8GB min ram
- 250 GB of disk space
- reasonable graphics performance
- As many USB slots as I can muster!
- Small case

With this in mind I started shopping and in the end chose this barebones PC.


This offered pretty much the best of all worlds, plus a decent spec with an i5 5200U chipset and Intel 5500 graphics processor.

This also supports a couple Msata drives, a SATA3 interface (cable supplied in the box) and 2 x SODIMM's. Plus dual LAN ports, Dual HDMI connectors, 4 x USB2 slots, 4 X USB3 slots, and the normal 12V in and speaker/mic connections etc.

You can buy i7 versions if you need something more powerful but of course the cost jumps. My experience using a cheap nextbook tablet suggested this i5 would be more than capable.

The PC  has all named brand chipsets, so its a standard Intel chipset, broadwell drivers, AC93 audio etc etc So all the drivers are in Windows 10 off the bat - no messing trying to find driver disks!  In fact the only driver I had to update was the Wavenode which has a kooky installer but that's not a Windows problem more a dev issue!

Shipping was reasonably quick and great comms from the seller. I was able to use paypal and protect my purchase too, so I felt comfortable with the buy from China.

The only things I can say is the model in the picture is slightly different from the supplied one. the supplied model has no RS232 ports anymore. I was a bit miffed by that but Hystou sent me 2 x USB - RS232 adapters for free (and yes with FTDI chipsets!) so cannot complain about that really :)

Shipping took about 10 days with a holiday weekend slowing things down.

While this was in shipment I set about looking at hard drive options.

I settled on a Solid State Disk for the new PC due to power needs, fast access and also noise .. no spinning components. But this comes with a warning!  SDD's have a HUGE amount of info on them on the net. Trying to find out what was best buy, price and performance was incredibly difficult but I can sum it up pretty easy!

- There's a lot of hoodoovoodoo about SSD's - some of the tech talk on them is quite
   questionable - so skip the bit that I did and focus on finding a reasonable priced one !
- Buy a well known brand - there are a lot of no name - no idea brands out there
- Buy a recent model one - technology has moved on quickly ... look for something modern
- Performance for this application is really a mute point - anything reasonable will do ... aim for   
  something in the 500mb/sec WR times - anything will be be
- Don't panic about extreme, PRO models etc. Look for something that has a good balance of
  price vs performance. It's not a gaming machine so does not need to squeeze every Ms of 
  performance out!

I finally settled on a 240 GB model as a balance of disk space and price. The Windows 10 install and basics like SSDR, N1MM, FLDigi, SDRbridge, CW Skimmer, DDUTIL etc comes in at about 30 GB. You could get away with a 120GB device to save a few $ but to be honest the few dollars saved might bite you later! I chose this disk which came in at about 170 NZD. 


You can of course choose an Msata drive if you want something smaller but larger sized Msata drives are still pricey. I chose the SATA 3 as a best option for $.

RAM is another wide area of choice. I chose a named brand 8GB SODIMM from Kingston and the fastest the board will support is 1666 MHz - it is a low power RAM slot - so just watch that. 

Oh...  one of the nice things about this PC is that it has WIFI built in and 2 antennas - one less box and you can connect external antennas to the two SMA ports!


Installing the parts in the case was easy .. 5 mins with a small screwdriver and that's it done!

They are nice and compact - just remember don't take the board out as its bonded to the case!

I installed Windows 10 and tried to upgrade with a Window 7 key but I didn't realise that this upgrade path is not supported. If you're upgrading from Windows 7/8 you need to install this first and then select the upgrade installers from the Windows 10 site. This worked perfectly!

Here's a tip too.... if you're building a new PC and don't have a spare W7/8 licence you can legitimately buy Windows 7/8 OEM licences on Ebay. You can grab these for like $25 install that key and then upgrade to Windows 10 for free. But be quick you can only do this inside the first year of Windows 10 and this will cut off at some point!  

Installing Windows 10 was super quick due to the SDD! That really flies.

I also installed the SSD monitoring software that SanDisk supply which can help manage SSD's and alert to any issues. All pretty painless.

After that I set about installing updates etc and then left the PC running overnight while it installed all the latest patches and updates.

BTW ... the SSD is a MUST!   I can boot from cold to a Windows 10 screen in 11 seconds! Recovering from sleep ... well a blink of the eye!  Definitely a huge advantage!

Next day I installed SSDR 1.5.1 and connected up one of the Flex 6500's.

Run up SSDR and .. bam ... perfect!  The PC supports all the normal windows resolutions and even 4K!  The display was sharp and crisp and despite using system RAM, does not use too much system memory.

Running a single slice barely tickles the box running at about 13% CPU. Even running 4 slices consumes about 40% CPU. The case is barely warm even running 4 slices. Power consumption was about 15W running 4 slices!

DAX ran straight out of the box ... no issues with drivers, no issues with LAN etc SSDR/Flex Control all work out of the box without issue.

Performance even for such a small box is quite amazing. I ran up a couple slices, plus N1MM, CW skimmers, SDR bridge, TELNET for DXcluster and it was running about 35%. A doddle for a this box.

So mission accomplished. Total cost under $450 USD for an i5, 240GB, 8GB machine. 

So far nothing I have done with this PC has been an issue. It's a comprise in space, i.e. no card slots but what you gain in size reduction, power needs, speed and noise reduction is great!  

I am pretty impressed so far. Will see how the box runs over the next months but I am already looking at an i7 for the main PC in my office and get rid of annoying fan noise.  It really is quite spooky to hear the lack of noise when you press the power button! Not even hearing the hard drive spin up ... hmmm very odd!

So there you have it ... I'll keep you posted on progress but thought someone might find the experience interesting and useful as I learnt some new tricks and there's some pitfalls you can avoid during the build, whereas I learnt them the hard way :)

Happy to answer questions!


Simon ZL4PLM

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Simon Lewis

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Posted 4 years ago

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Phil - N6ERP

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Thanks Salvador.. Still deciding on the monitor arrangement. In my case, space in the shack is limited, will probably just go for one 24 inch monitor for now. The 3 criteria are it must be RFI free, clear, and operate off of 12vdc to run from the battery bank. Still looking for something that meets the last two wants. Not sure how to know if its going to be noisy or not without trying it along with a good cable decorated with plenty of snap on ferrites. If anyone has any suggestions, im all ears.

Anyways not wanting to hijack a thread here, just planning to share any significant findings to the group.. Tnx.

Also, received the shipping tracking number today, so better get crackin'.
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EA4GLI - 8P9EH - Salvador

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I find that HDMI connection to the monitor is a great way to avoid RF.
I have 2 AOC monitors which have worked great as their power supplies do not produce any noise and they withstand RF without issue. However, the one connected with VGA from the laptop gets a bit affected by RF on 80m while the HDMI one doesn't even blink.

My particular model AOC E2461FWH needs a 12v 3A power source to work. I think a lot of the super thin LCD displays use external power sources.
I got lucky with these monitor in Barbados as they were the only ones available when I went to the store. They end up being great monitors that have worked flawlessly.

My ideal configuration would be a large 35+ inch 4k monitor in the middle. Those curved ones seem great, and a couple of 24s on the side. I would run the 4k off the main video card and the other monitors off the motherboard or even a USB3.0 video card add-on.

I will keep my rotor control programs, propagation, sat monitoring, etc... on the side monitors, and run SmartSDR, Logging/Cluster and website on main 4k monitor.
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Jim Gilliam

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I am using a dedicated fanless PC for all of my peripheral control and just love it. I have wondered if Flex has considered building on this idea to support their Flex radios with all the various third party programs loaded in firware or an SSD. Also using Softether so that the Flex 6500 is "WAN-able."

Jim, K6QE

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EA4GLI - 8P9EH - Salvador

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Any update on these Fanless PCs? Did you guys get them setup? How are they working out in the radio shack? Any pictures?
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Jim Gilliam

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Yes! I purchased the Hystou custom ordered with two 256 GB SATA drives. I modified it by drilling a hole in the side and adding a power jack to run two wires to the on/off switch. I remote a relay to remotely turn the computer on/off over the WAN. I added Smartether server, SmartSDR 1, Windows 10 (I bought a version with a USB drive from Microsoft) and now remote my 6500 100 miles away at my cabin in Big Bear. The computer just operates wonderfully and runs very cool. Very happy with it. I use the second SATA drive to make images of the drive C:/ operating system in the event of some problem cropping up with new version of Windows, etc. This summer I'll post pictures on QRZ.com.

Jim, K6QE

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Winston VK7WH

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I also bought one - i5 16GB memory 250GB SATA 3 SSD. Excellent performance, it runs faster than my main shack computer. 4 Panadaptors, 8 slices without a hick up. I'm very happy with it. As I also operate a (Solar Powered) remote station my only problem was not being able to remotely switch the computer on and off, as I need to reduce the 24/7 load as much as I can. So far I have been a little reluctant to run external wires from the momentary contact on/off switch to a WEMO Maker I have because of warrantee concerns, but, hey, Jim's trail blazing post above has given me the confidence to get out the battery drill!

Jim, if you have time, I would very much appreciate a close up photo or two, showing your modification in detail. I presume you didn't take the main board out and attached the wires to the tiny lugs at the top of the power switch, or did you find a better solution. I am a little concerned about the clearance issues between the lugs and the switch mount. Did you find that any rfi suppression was necessary other than using a twisted pair?

You can email me if you prefer at vk7wh@wia.org.au

A very Happy New Year to everyone.
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EA4GLI - 8P9EH - Salvador

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I would like to see more info as well about the remote on off mod so I would love if it can be shared here.
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Jim Gilliam

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Unfortunately, I have the computer 100 miles away. When the snow melts enough to get up to my cabin (I don't have a 4-wheeler), I'll take pictures. Basically, I drilled a hole in the side to mount a mini-jack. The mini-jack supplies 12 VDC to a relay mounted next to the ON/OFF switch. I tack soldered two small wires from that switch to the relay. The power leads to the relay are shielded, and there is only about 1 inch from the relay to the switch so I had no RFI problems. I remote the relay with a standard AC controller over the Internet. I just toggle the A/C power to a small power supply which energizes the relay. I manually toggle the relay on and off to switch the computer on and off. Sounds a little messy but it looks nice and works great.

Jim, K6QE

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Winston VK7WH

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Thanks Jim. Yes I understand the access difficulties. My site is a 2 hour drive each way, but without the snow! Two further questions if I may.

1) The front panel on/off switch feels like a momentary contact switch (I may be wrong) Do you pulse the relay to switch the power on and off, or do you latch the relay for power on and release it for power off?

2) Am I right in assuming you are soldering the two connecting wires to the relay to the two tiny tabs on the top of the power switch?

Thanks again for your help Jim, and a HNY

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Martin Ewing AA6E

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@Simon: Sounds like you're enjoying the change to re-engineer everything.  My only comment is that it's easy to over-think the PC requirements.  Current SSDR, along with typical ham apps - fldigi, logging, and wsjt-x (for me) runs very well in fairly modest PCs.  Most any mid-level consumer PC you buy now will be fine for SSDR. (Except somewhat crippled by Win10, but that's not the hardware's fault!)

I built up my DIY quad core i7 system with a significant graphics board (GeForce GT640) in order to run an older version of SSDR, but it's totally unnecessary for the current version.  In fact, I usually run BOINC scientific batch programs on all 8 hyperthreads + GPU in the background while running SSDR ham operations with no issues.  (And AFAIK, SSDR is mostly single threaded.)

In our market, it's hard for a DIY PC to compete in price with consumer PCs.   It's just a question of what's more fun for you. Cheers!
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Big house, big shack, big radios, just get the big case.     http://www.techspot.com/products/cases/corsair-obsidian-900d.89123/
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K1UO - Larry

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FOR SALE if anyone still interested:

1. FMP05B-i5-5200U   Equipped with 8gb RAM 256gb SSD and 300MB WiFi     Purchased new Mid NOV 2015.

- CPU: Intel® CoreTM i5-5200U Processor (3M Cache, turbo up to 2.7 GHz, 2.2 GHz base speed)

- Graphics: Intel HD Graphics 5500, support ultra 4K HD
- RAM/ Storage: 2* channel DDR3L memory slot, 2* mSATA SSD slot and 1* 2.5" SATA3 HDD/SSD Bay
- I/O: 2* HDMI; 2* RJ45 LAN ports (Gigaibit); 2* RS232 Serial ports(male DB9) ; 4* USB3.0; 2* USB 2.0; 1* Power switch; 1* DC IN; 1* SD Card Reader; 1*MIC; 1*SPK; 2* Wifi antennas

- Win 7 installed.

$300 shipped CONUS.     K1UO [at] arrl.net
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Does anyone have a current link for the company who sells these? Link included in the beginning of his discussion seems to be gone.
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Peter K1PGV, Elmer

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Try http://www.hystou.com/