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Episode 8: Puttering about in the summer doldrums
The prime contest seasons are behind us and ahead of us, so we’re in what I like to consider the summer doldrums.
Not a lot of really big contests to jump into, but plenty of interesting events if you’re looking for some ham radio action on a late spring and early summer weekend.
Let’s go take a look in Episode 8 of Zone Zero.
Welcome to Zone Zero, the ham radio contesting podcast. This is Bud, VA7ST, your faithful contesting observer, reporting in after a couple of weeks of downtime following the big WPX RTTY 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, Ameritron and RF Parts all sell 3-500ZG tubes for about the same price — US$220.
RF Parts won’t ship tubes outside the US. But DX Engineering and Ameritron will ship 3-500 tubes, and get 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,
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By VA7STThe prime contest seasons are behind us and ahead of us, so we’re in what I like to consider the summer doldrums.
Not a lot of really big contests to jump into, but plenty of interesting events if you’re looking for some ham radio action on a late spring and early summer weekend.
Let’s go take a look in Episode 8 of Zone Zero.
Welcome to Zone Zero, the ham radio contesting podcast. This is Bud, VA7ST, your faithful contesting observer, reporting in after a couple of weeks of downtime following the big WPX RTTY 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, Ameritron and RF Parts all sell 3-500ZG tubes for about the same price — US$220.
RF Parts won’t ship tubes outside the US. But DX Engineering and Ameritron will ship 3-500 tubes, and get 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,