Adding the Ameritron AL-80B to the shack

Written by admin On June - 12 - 2017 Comments Off on Adding the Ameritron AL-80B to the shack
Note: This post is a companion piece to the June 11, 2017, Episode 8 of the Zone Zero podcast.

My new Ameritron AL-80B on the left, and one of my SB-221 HF amplifiers on the right.

The prime contest seasons are behind us and ahead of us, so we’re in what I like to consider the summer doldrums. I have enjoyed a couple of weeks of downtime following the big WPX CW contest at the end of May.

Since then, I’ve been in station-building mode. Nothing major, I guess, but it sure has been an interesting couple of weeks as I have been addressing the shortage of HF amplifiers.

The little side-trip into technical country began the night after WPX CW. With nothing to work on, I decided to fix up a failing SB-221 amplifier, which had a tube go dark on me a couple of months ago. After checking things out I narrowed the problem to the now-dark Eimac 3-500Z tube itself.

That old tube has been in service since the day the amp was built in 1978, that’s 39 years of faithful high power for me and the unknown number of hams who owned it before me so that tube owes me nothing but happy memories. But I couldn’t give up on it without a fight.

Taking a tip from one of the online reflector groups, I re-soldered the filament pins – actually doing all five pins while I was at it — and the tube came back to life just fine.

But that got me going down a rabbit hole of changes to the amplifier. I spent an evening re-wiring for 240-volt service, as I now have a 240-volt circuit in the radio room. But when that didn’t appear to work, I returned the amp to 120-volt configuration.

After three more nights I finally traced the problem back to the breaker box. In the load-center, someone had put the double-pole breaker on a single pole of the mains power. I moved that double breaker one position over, and solved the problem – nice and stiff 240-volt service in the shack.

I spent an additional hour reconfiguring one of my SB-221 amplifiers for 240 volts, and haven’t looked back.

But that tube I mentioned? It bothered me that I don’t have a backup tube in case one fails in either of my Heathkit amplifiers. So I went online looking for a spare.

DX Engineering and RF Parts both sell 3-500ZG tubes. RF Parts won’t ship tubes outside the US as they apparently don’t want business from Canada or other non-American hams. But DX Engineering will ship 3-500 tubes, and gets my endorsement. 

However, the currency conversion from US to Canadian dollars makes the price from any retailer a bit high — US$220  right now is $296 Canadian, plus shipping. So I looked around on Canadian swap and shops for a used 3-500Z tube.

And amazingly, I found one!

Well, it took a few days of hunting as these aren’t the most common spare part around. But Rick VA7EM, about half an hour’s drive from where I live, was selling an Ameritron AL-80BX amplifier with a spare 3-500Z as part of the package.

My ham-guy brain was ticking over pretty fast as I realized an AL-80B is a fine modern amplifier with a single 3-500Z tube providing about 600 watts out on 160M CW, plus it does the WARC bands for a bit of DXing firepower. My trusty SB-221 amplifiers have dual 3-500Z tubes and are bulletproof contest units putting out a kilowatt all day long if I wish, but they don’t do 160M or the WARC bands.

So, I got permission from the station manager – my lovely wife Kim – to make a call and see if I could acquire the amplifier and spare tube. The whole package cost me $1,000 – which is more than I went into this expecting to shell out for a spare tube, but I got a very solid, almost-new amplifier in the bargain.

I like that the AL-80B is still manufactured and sold in stores – which means parts and advice should be readily available if ever needed.

The retail price in Canada, by the way, is $2,300 – so I saved $1,000 plus another $300 in federal and provincial taxes and shipping charges buy buying slightly used and not having to ship anything.

So what does that all have to do with contesting?

Simple. Station-building – getting the gear – is a big part of the ham radio hobby and especially competitive contesting. Better, higher antennas, radios and other equipment that makes operating easier and quicker, even things as basic as more or better antenna switches, all improve your game.

The RTTY contest amplifier heat treatment

Over the past weekend, the AL-980B had its maiden voyage here.

I ran the first leg of the DRCG Worldwide RTTY contest on the AL-80B, and had a great time. I didn’t notice a performance difference with 500 watts on RTTY using the Ameritron versus more like 700 watts with the SB-221 amplifier.

I didn’t expect to work more or fewer stations with either amplifier. Rather, I wanted to compare them running teletype, which is a 100 per cent duty cycle that pushes amplifiers to their limits.

Unless you have one of the big amplifiers costing 10 times the price of an SB-220 today, RTTY is not a mode to transmit continuously for more than a few seconds at a time,. If you keep things short and provide cooling pauses of a few seconds between transmissions (a technique which is perfectly aligned with the pace of RTTY contest CQing cycles), your amplifier should run a RTTY contest all weekend long without any issues at all.

The difference I saw was quite clear: the SB-221 ran a lot cooler – the plates of the single tube in the Ameritron glowed dull red and then orange after a few transmissions, while the SB-221 tubes never even began to turn color, and remained a lovely dull carbon gray.

The SB-221 amp won the heat shootout, but it doesn’t do 160M or WARC, and the Ameritron wins for pure flexibility and I also like that it has a reasonably accurate SWR and power meter in it.

So, now I have a few high-power options and the redundancy I want for operating in the big contests that really matter this fall.

Listen to the Zone Zero podcast for more on the AL-80B’s first performance from VA7ST.

Contesting, General, SB-221, Uncategorized

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