Monthly Archives: May 2013

Shack Remodel and Amplifier

It’s been a while since my last blog post because I’ve been enjoying using the new tower and antenna. Boy, what a difference a yagi on a tower makes! There’s just no comparison to my ground-mounted vertical. Signals that are barely there or inaudible on the vertical are armchair copy on the yagi. Working DX is much easier and I’ve been running up my DXCC totals and enjoying the experience.

Since getting the tower up, I’ve also concentrated on working all states and confirmed the last one I needed (West Virginia) a few weeks ago. No QSL cards traded hands for this — all confirmations were via LoTW. The postman delivered this last week:


So does that count as WAS in 30 days, or WAS in 33 years? Hmmm…

After operating for a month with the new setup, I started thinking about replacing my operating desk, which was too small to spread out the way I like to operate, with a legal pad for taking notes, paper logbook, keyboard, paddles, etc. all at arm’s reach. Since I was planning to add an amplifier to the mix, it was time to start looking for a new operating desk.

I started the search at local office supply stores, but nothing I found was deep enough at a reasonable price, so I started to consider alternatives. The local Ikea is near Ham Radio Outlet, and since I planned a trip to HRO to pick up an antenna switch, I stopped by to check out their desk offerings. Nothing seemed deep enough for my liking. Most desks seem to be a maximum of around 30″ deep unless you go to an expensive “executive” model. While strolling around, I spotted a dining room table that looked ideal. It was deep (39″) and wide enough to accommodate lots of equipment. I also picked up a small bookcase unit to use as an equipment riser and shelf on the desktop to help organize the equipment.

I’ve never owned an amplifier, and only used one at the W6BB club station while in school. I wanted something with at least a kilowatt of output, and started considering various Ameritron models, such as the AL-80B. As such things often go, I found myself thinking I should go right to the legal limit and started considering the available options. Once again, I looked at various Ameritron models, including the AL-82, AL-1200, and AL-1500. I was pretty much settled on the AL-82 when a trip to the Visalia DX Convention prompted me to look at other offerings. RF Concepts had a booth at Visalia with their 8410 and 9500 models on display. Alpha has always been considered one of the gold standards in amplifiers ever since I’ve been a ham. Who hasn’t seen their ads with the brick on the key in various ham mags? Although the 8410 was several kilo bucks more expensive than the Ameritrons, I thought, what the heck, go for the 8410, so I plunked down my plastic and three large boxes arrived on my doorstep four days later.

The 8410 is a legal-limit manual tune amp. It uses two 4CX1000A tetrodes to generate 1500 watts with plenty of headroom. It comes in two separate boxes: one containing the main power transformer and the other the main amplifier chassis. The transformer is shipped in a separate box because of its weight and potential to warp the chassis if it’s handed roughly in shipping. The third box contained two spare 4CX1000A tubes that RF Concepts was offering as a show special.

The amplifier itself was double boxed and the two boxes were firmly padded by foam between the boxes and inside the inner box. The gorillas at FedEx would have to try extra hard to damage this arrangement. The amp chassis itself is fairly light without the transformer.

AmpInBag-1200 Amplifier Main Unit

Installing the transformer required removing the top cover, which is secured with about a gazillion screws. Once the cover was off, one can easily see the build quality of this amp and why it commands the price it does.

Inside-1200 Under the Cover

The transformer is shipped in a smaller box, and, like the main unit, is double boxed and surrounded by several layers of foam.

XformBox-1200 Transformer Box

The transformer is bolted down to a piece of plywood to keep it from moving around in its box. Unlike more conventional transformers, this transformer is a toroid.

Xform-1200 Toroidal Main Transformer

The transformer mounts in the right side of the chassis and is secured via four bolts inserted from below the chassis. It’s not really possible to get to the bolt holes with the chassis laying flat on the tabletop, so the alternate approach is to tip the chassis up on its right side and slide the chassis around the transformer until the holes line up. This is easier said than done, and it’s really a two person job. Once the transformer is bolted in place, all that remains is to replace the top cover and the countless screws.

XformInstall-1200 Transformer Install

I next tackled the assembly of the new “desk”, which follows the usual Ikea pattern. This assembly went smoother than most with only one minor glitch. One of the 90 degree metal corner brackets had two holes mis-drilled. Five minutes at the drill press fixed that. The little bookshelf unit went together quickly, or it would have if I built it as intended. Since it’s designed as a bookshelf, there is no need for access to the back for cables and such. To accommodate the cables running to the various equipment on the shelves, I drilled two rows of four 2″ holes using a hole saw. Particle board is hard — my hole saw was literally smoking after each hole.

I picked up an MFJ cantenna dummy load on my trip to HRO as my previous load was only rated for 300 watts and would not handle the power generated by the new amp. This dummy load consists of a one gallon paint can filled with mineral oil and a 50 Ohm resistor immersed in the oil. It can handle legal limit long enough to tune the amp.

After putting everything back together, I was ready to go.

Shack-1200 New Operating Layout

Tuning the 8410 is a piece of cake. Mind you, the last time I used an amp was about thirty years ago, but the process is simple. I really don’t know why I hear so many guys tuning up on the air for literally minutes at a time. I can do it in about five seconds. The extra power is certainly noticeable when working big pileups. I’m getting through much faster than I did with 200 watts.

One of the nice features of the Alpha 8410, and one that ultimately sold me on this amp, is its ability to send telemetry to a computer over a USB port. Alpha uses this for factory test and to upload firmware, but full operating data is also available. The raw data is difficult to interpret, but Dan, AE9K, has written a spiffy Monitor application for Windows that retrieves the telemetry data from the amp and displays it as a series of bar graphs and numerical data. The amount of data that is displayed far exceeds what’s shown on the LEDs on the amp’s front panel. I’ll post a screenshot of this utility when I next update this blog.

That’s all for now. 73, and good DX. See you in the pileups.