26 August 2023

The Most Important Amplifier In Ham Radio

The title is a pretentious joke, but there is a kernel of truth in there.

A few days ago I wrapped up my HobbyPCB HardRock50 amplifier build, and I'm in the process of testing it with a variety of QRP rigs. So far so good with the Yaesu FT-818 and the Icom IC-705, and testing with the Elecraft KX2 is coming up. Right now I'm updating the external interface for the IC-705 that is manufactured by HobbyPCB, an interface that allows the amplifier to follow band changes on the radio and trigger tuning cycles

Earlier today I created a video showing the start-up procedure when using the amp and the IC-705 interface with the IC-705. The video shows how the IC-705 interface controls band switching (via Bluetooth), tuning and amp triggering. The interface works quite well, but it is an extra cost item ($70 as I have it configured) from HobbyPCB. Note - you DO NOT need this interface to run the IC-705 with the amplifier - the interface just takes care of the band switching and tuning duties, something you can do without the interface. You just have to do those tasks manually, and it's not at all difficult. 

I'm quite happy with the output. Signal reports from fellow hams are good, and I'm easily getting 50 watts PEP on sideband when driving the amp with 3 watts of output from the radio.

Building this amp was, as it's popular to say today, 'a journey', and I've outlined much of it in earlier postings. This is the second of these amp kits that I've built, and I learned a LOT on the first build. The reason I built this new amp is because the previous amp kit was an early model (shipped in 2014 but never built) and it had some issues regarding the ability to interface with the IC-705. I figured I'd start with a clean slate (and somewhat improved soldering skills) with a current production kit from HobbyPCB that included the internal tuner board. While this is not a tough kit to put together, it took me several months to get it done as work, family commitments and other factors got in the way. 

One of the hiccups was a blown capacitor on the amp board, which the manufacturer put down to it being a tantalum cap with known tendencies to let out the smoke when voltage is first applied. Jim Veatch, the owner of HobbyPCB, said they are likely going to switch capacitor types on the next production run. He cheerfully sent me two replacement caps. The job to replace them gave me the convenient excuse to buy a hot air re-work station to get the remains of the old cap off the board, get things cleaned up and the new cap in place. 

Luckily the damage was limited to the blown capacitor

Getting set to replace the blown capacitor

Another issue was the maddening discovery that the mounting holes for the tuner board had been mis-drilled in the case - basically they were drilled 'backwards', but you don't immediately know that until you go to mount the tuner board in the case and button everything up for testing - it just doesn't fit, and too much forcing can result in some bent connector pins (don't ask me how I know...). Again, Jim at HobbyPCB got back with me and let me know that their recent production runs had the holes on some of the cases drilled improperly, and he's only finding them when people like me bring up the issue. He offered to replace the case but I had to ship the old one to him first, or he could send me a template that would allow me to drill my own holes in the proper location. I opted to go the template route.

So, I can't emphasize too much that this is a 'hobby' build - the instructions are very good, and on-line support is good (Jim answers emails promptly and very courteously), but you are still likely to run into glitches like I did. This is where the hobby aspect comes into play, and you're kind of expected to do your own troubleshooting. Adversity builds character, right? But HobbyPCB also states that the price of the kit includes a working amplifier, so if you get it all together and simply can't get it working you can ship it off to Jim and he'll diagnose and fix whatever's wrong, for free.

The IC-705 interface module - a box that connects between the amp and the 705 and allows
automatic band switching and tuner operation. It's basically an Arduino board with a Bluetooth
interface. I just got through soldering in the add-on board that drives the tuner in the HardRock50
(the lighter colored board in the upper right)

Another challenge for those of you not used to running bootloaders is updating the firmware. Your kit will likely ship with a slightly outdated firmware version. Updating the firmware isn't tough, but you have to install a bootloader on your computer and run the update from there. It's a well documented procedure, but might put off those with limited computer skills.

Last, although everything about this amp and the add-on components like the tuner and control interface are well documented, the HobbyPCB website is something of a dog's dinner in terms of organization, and HobbyPCB has some dead links and pointers to outdated files out there. They need the help of a good web developer.

So what's the use case for this amp? For me it's simply this - with the demise of portable all-band, all-mode 100 watt rigs like the IC-7100 or the FT-857, I am looking for more 'oomph' for both my IC-705 and my KX2. I love those rigs, but feel that they are limited by their 10 watt output, particularly when working voice. Let's focus on the IC-705 - an incredibly capable radio that brings together all the features anyone would need for portable operations. I consider 50 watts as something of a sweet spot for portable work. In most cases going from 50 - 100w output doesn't really get you much beyond greater power consumption. I also like the idea of the two components in separate packages. If I only want to run digital I can go out with just the radio and work at 10 watts. If I want to run voice, I can bring along the amp and push things up to 50 watts. With the internal tuner in the amp I can also leave the Icom tuner behind. It's all about options and capability.

OK, what about this silly 'most important amp in ham radio' claim? Well, here's the truth of it. To be an effective portable shack-in-a-box radio the IC-705 needs to put out more than 10 watts. This is particularly important if you want to use the rig for EMCOMM applications. Ten watts may be enough for digital modes, but for SSB it's not enough for reliable & repeatable comms. There are a number of solid state amps on the market that will work with the IC-705, but they generally fall into two categories - low cost, low output Chinese manufactured amps of poor quality, and high quality (and expensive) 100+ watt amps designed for in-shack use from companies like Elecraft, RM, ACOM and others. The HardRock50 is the only high quality, field portable, well supported and reasonably priced amp available for QRP rigs. This means the HardRock50 stands alone as an amplifier that can turn the IC-705 into a serious field radio for EMCOMM use. So while not the most important amp in all of ham radio, it is still the best option to turn your field QRP rig into an effective tool for reliable communications.

The next step is testing using a battery instead of a power supply - I'll test using a 12 amp hour LiFePo battery to see how long that holds up in field use. I'll also be testing with the KX2. So stay tuned!

W8BYH out

05 August 2023

Considering the IC-705?

Earlier today I watched a YouTube video by Ham Radio DX doing a 'should I buy' review of the IC-705. While the video is otherwise unremarkable, the author did mention a few things that clicked with me, and started me thinking.

I've owned my IC-705 for over two years, and really like it. Notice I say 'really like', not 'love'. There have always been a few things about the 705 - issues and shortcomings - that bother me. I've written about most of these issues on this blog, so I won't go back and beat the dead horse (just search on the blog for 'ic 705'). I'll just say that while the IC-705 stands alone in its class it still has some shortcomings.

Which leads us to this post, and the ideas spurred by the Ham Radio DX video. Here's my advice to folks considering buying an IC-705, or have bought an IC-705 and are struggling with some of its shortcomings:

The IC-705 should be considered as nothing more than the core of a larger radio system. It is minimally functional right out of the box, but requires a compliment of additional hardware and software to be considered a fully mature and capable system.

To be fair, this concept applies to virtually every other QRP rig I've owned or used, including the highly touted Elecraft KX series. However, Icom seems to specifically market the IC-705 as a complete, all-in-one rig that really doesn't need any add-ons. But out here in the real world, it does.

So, if you think about the IC-705 as being just the core of a larger 'system' you will be less likely to focus on its shortcomings and become disappointed. The other components of the system will effectively address the shortcomings and make it an incredibly capable best-in-class radio system, but at a cost.

What are these system components? Here's my minimum requirements list:

  • Environmental protection for the radio. Something like the Peovi or Windcamp cages or one of the dozens of 3D printed cages on offer on eBay. I particularly like the Peovi solution because of the available polycarbonate snap-on cover made by SideKX. ($285 current price for the Peovi)
  • Antenna tuner. Please, spare me the righteous talk about only using resonant antennas. This is the real world, and I like frequency agility. Compromised antennas are often a fact of life, particularly with lightweight portable radio setups. While just about any tuner will work with the 705, the one that works best in my experience is Icom's own AH-705. It's an incredible tuner, although somewhat big when compared to the radio itself. ($360 current street price)
  • Power. To get the full 10 watts out of the IC-705 you'll need an external power source. The good news is that it doesn't need much external power. Like a lot of 705 owners, I use a small 4.5 amp hour lithium-iron phosphate battery that will keep the 705 running at 10 watts for well over 8 hours. ($65 from Bioenno)
  • Software (and the computer to run it on). Software is only required if you run digital modes, but since most folks buy the 705 for its digital mode capabilities, some software is required. The only software package I consider absolutely essential is Icom's own RS-BA1 v.2 software. It is the remote server component of this package that allows you to control the radio via a wi-fi USB connection. Why not just use the USB port on the radio? Because Icom failed to properly shield the IC-705 and the radio is highly susceptible to RFI coming in over the USB connection. It is so bad that, when running digital modes like FT8, it overwhelms the radio on all bands. I wrote about this in an earlier post so I won't re-hash it here. Suffice to say, you'll need the RS-BA1 software. ($140 current street price)
These minimum system add-ons come to $850, in addition to the base cost of the IC-705. There are cheaper options on the market for things like the protective cage, tuner and battery, so consider this $850 a high-end estimate. It just reinforces that reality that most IC-705 owners will face at some time or another. You don't have to buy these at the same time you buy your radio, but to exploit the full capability of the 705, at some point you'll likely need to add them.

If you go into the IC-705 purchase knowing it takes these add-on items to reach what we called in the Army 'full mission capability' you are much less likely to be disappointed with your radio.

W8BYH out