Tiny Elephant's Contest Corner The Latest Contest News - A NARC Bulletin Exclusive A monthly column by Ed Deichler, K2TE

Let Me Amplify That...

Unfortunately, this issue of the NARC Bulletin will be out before the results of Field Day 1998 can be included. I have no doubt, however, that with the multitude of beams and wires we use, we will reap a bountiful harvest of the bands. Field Day has always been a domestic contest that provides excellent training for future contesters while allowing veteran operators to keep their skills sharp. The emergency preparedness that is the focus of Field Day makes low-power operation a necessity when working from a temporary set-up. With all the activity observed during Field Day, the casual operator has to wonder: Why bother with a linear amplifier?

At first glance, I have to agree that using a linear amplifier on Field Day (or any other stateside contest) makes about as much sense as using a bullhorn to talk across a crowded room. However, when working a DX contest or chasing a DXpedition to a rare QTH, an amplifier becomes a necessity in order to be heard. I have talked to local contesters who have been fortunate to work a contest from the pile-up side. They recognize many of the local stations and, although the locals are using an amplifier, the signal strengths are all about the same level. This explains why a 100-watt station often must call indefinitely or come back to the frequency periodically to see if the pile- up has died down enough to stand a chance for the DX station to hear him.

The more compelling reason for using an amplifier is the need to get through when conditions are marginal. This is especially true on the bands like 80 and 160 meters where the atmospheric noise can produce a headache in a hurry and easily bury a signal that would be S9 on 20 meters. As a case in point, I recently worked 3B7RF in the Indian Ocean on 80 meters one evening. He was very weak among the static bursts and, since we were both running amplifiers, I’m sure I was weak on his end.

It is this pursuit of being heard reliably under nearly all conditions that has spurred amateur amplifier development. The early days of ham radio featured a “cat whisker” receiver design that was not much better that two cans and string for signal sensitivity. The vacuum tube came along and greatly improved signal levels but the physics of receiving weak signals lagged behind as early receivers had “barn door” front ends that let in Grandma’s sewing machine hash with the desired signal. Building early amplifiers required ambition as big as the parts themselves. Having a secondary skill as a cabinet maker was a definite asset since the tubes would occupy one cabinet, the power supply another, and the tuning capacitors and coils still another.

Amateur amplifiers became commonplace 30 to 40 years ago during the hey-day of American ham gear manufacturers. Many of these amps are still in use today long after the demise of the companies that made them: Collins 30L1, Heathkit SB-200 and SB-220, Henry 2K and 4K, and National NCX-2000, to name a few. These amps are down to a manageable size where they can fit on the desktop or at least along side of it. On the air, an amp’s specific identity was rarely revealed as hams referred to the “foot- warmer”, “brick”, “hammer”, or “afterburner”. An amplifier’s tubes sparked as much debate as the type of engine in the “muscle cars” of the 60s. Many a rag-chew could be heard arguing about the virtues of such “bottles” as a pair of 807s, 813s, 3- 500Zs, 4-1000s, and 572Bs. I can personally attest to the ruggedness of two of these models when I’ve keyed up on the wrong band or wrong antenna and the tubes didn’t explode in a shower of sparks that only Frankenstein could love.

Many of today’s amplifiers have incorporated protection features to protect the tubes from over-anxious operators as well as foster peaceful coexistence between the beastly amp and dainty solid-state transceiver feeding it. Modern amps such as the ETO Alpha models and Ameritron have added full QSK operation, SWR protection, mistune protection, and over-temperature protection. Such features make it difficult for all but a complete idiot to ruin the equipment. (Maybe that is why ETO keeps turning down my requests for an amp to beta test). These features are definitely welcome during the latter part of a 48-hour DX contest when fatigue sets in and the operator starts band-hopping looking for multipliers. New amps also feature better shielding and packing design thanks to FCC requirements for type acceptance that requires meeting stricter spurious emissions. This requirement reduces the effects of RF interference getting into the solid-state transceiver and wreaking havoc. It also helps make life a little easier for the computer and its peripherals cluttering today’s ham shack.

So next time you find your pulse rate ramping up alarmingly while trying to snag a new country in a pile-up, think about kicking on the “louden-boomer” for a few minutes. You might be able to get to bed or off to work early for a change.

I apologize for not spotlighting some contests for this month. Hey, it’s Summer and its Field Day. Enjoy the time to reflect on the fun and tackle those antenna projects.

73, de K2TE

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