I was very glad to see that Mike, AA1TJ, is back in his underground shack and once again pushing the limits of QRP technology. This may be one of his greatest QRP-capers:<\/p>\n
Gents,<\/span><\/p>\n It was one of those rare days on the bench where everything I touched<\/span> Better yet, over the weekend I found a wonderful circuit in a<\/span> I’ll cut to the chase as I want to get back on the air ASAP. The<\/span> I’m headed back to the shack once I send this message. I’m rock-bound<\/span> Right, here I go.<\/span><\/p>\n 73\/72,<\/span> I was very glad to see that Mike, AA1TJ, is back in his underground shack and once again pushing the limits of QRP technology. This may be one of his greatest QRP-capers: Gents, It was one of those rare days on the bench where everything I touchedturned, if not to gold, at to least silver. … Continue reading “AA1TJ’s Point Contact Contacts”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[157,85,31],"tags":[],"class_list":["post-4157","post","type-post","status-publish","format-standard","hentry","category-aa1tj","category-minimalist-radio","category-radio-history"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/4157","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=4157"}],"version-history":[{"count":0,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/4157\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=4157"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=4157"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=4157"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
turned, if not to gold, at to least silver. At the end of my last shop<\/span>
session on Friday I could only get Jack Ward’s point contact<\/span>
transistor to oscillate as high as 385kHz. And that was without a<\/span>
load. I brushed up on the theory over the weekend and set upon the<\/span>
circuit today after lunch with a vengeance.<\/span><\/p>\n
transistor handbook dating from 1956. This circuit first appeared in<\/span>
“Wireless World” in may of 1954 (“160 Metre <\/span>Transistor<\/span> Transmitter”).<\/span>
At first glace, the circuit looks identical to <\/span>George Rose<\/span>, K2AH’s<\/span>
historic circuit. However, Mr. Cockle (don’t yet know his call sign)<\/span>
shows a dotted transformer and headphones next to the collector bias<\/span>
transistor. He’d figured out the point contact oscillator could double<\/span>
as a direct conversion receiver! A 1954 vintage “Pixie,” only<\/span>
simpler! The key to it all is the signal tank in the base circuit.<\/span>
That is to say, the transmitter output power is picked off the base<\/span>
circuit tank. It sounds daft, but bear in mind the circuit has more in<\/span>
common with a tunnel diode oscillator than it does a feedback<\/span>
oscillator that most of us are familiar with.<\/span><\/p>\n
Western Electric <\/span>point-contact transistor<\/span> is sending 12mW up the<\/span>
transmission line<\/span>. The same circuit is working FB as a receiver with<\/span>
full break-in and 800Hz RIT offset. I put it on the air at 2234 this<\/span>
evening. At 2247 K1IQI answered my CQ. He first sent a “QRZ?” so I<\/span>
repeated my call several times. He came right back with my call and<\/span>
gave me a 219 report from Monson, MA. Unfortunately, QSB wiped out my<\/span>
next transmission. He returned with an apology, wished us better luck<\/span>
next time and then he was gone. Close but no cigar!<\/span><\/p>\n
on 3533.6kHz. I’ll be calling CQ and listening until 0300, or so.<\/span><\/p>\n
Mike, AA1TJ<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"