I was at the point where I needed to hook up the radio and do the final RF testing, following the steps in the SB-200_Manual<\/a> starting on page 44.<\/p>\n All seemed simple enough yes?<\/p>\n I connected the radio to the input of the amp, the output of the amp going into the Bird 43 meter, then out of the meter going into my MFJ-250 dummy load.<\/a> (Speaking of which, does everyone of these leak the mineral oil back on to the top of the can from the SO-239 antenna jack mounted in the middle of the lid?\u00a0 What a FREAKING MESS!<\/em>)<\/p>\n Well, I get everything connected and hit the CW key on the radio.\u00a0 The SWR meter on the radio pegs on high SWR. and <high SWR> flashed on the radio.\u00a0 Humm.. that is not good.\u00a0\u00a0 I check the cables and do it again for the same result.\u00a0 I disconnect the amplifier so I am going from the radio – Bird – dummy load.\u00a0\u00a0 Transmit.<\/p>\n Flat SWR on 80m – 10m.\u00a0\u00a0 Hummmmmmmm…<\/p>\n I set everything back to put the amp in line.\u00a0 Try it again.\u00a0 Again, the SWR meter on the radio pegs on high SWR. and <high SWR> flashed on the radio.\u00a0 This isn’t the way it should be.<\/p>\n I flip on the amp and key the amp using my foot switch.<\/p>\n ‘CLACK’ I hit it and release several more times.<\/p>\n ‘CLACK’\u00a0 ‘CLACK’\u00a0\u00a0 ‘CLACK’<\/p>\n I hit the key on my radio to put out a steady carrier…<\/p>\n ‘sizzzle sizzle sizzle’<\/p>\n replied the amp from some region around the tubes.\u00a0\u00a0 SH*T\u00a0 !!!<\/p>\n Something was not right. I stopped keying after about 2 seconds and shut off the amp.<\/p>\n Watching the HV bleed down on the meter, I try to transmit again as the directions state.\u00a0\u00a0 This time, RF passes through the amp for about 2 second, then the SWR pegs on the radio.<\/p>\n “Hello Google…” as my fingers start typing on my phone looking for answers.<\/p>\n Withing a few minutes, I come to see that this is a common issue when the relay is bad in the amp.\u00a0 DAMN.\u00a0 There are steps to clean it, but, again, with the unknown history of this amp, why bother. I opened the case to look at it, and compared to the other relays I have seen in some of the amps, this one looked ‘cleanish’.<\/p>\n Looks can be deceiving. Make sure to test everything with a meter.<\/p><\/div>\n However, looks can be deceiving.\u00a0\u00a0 Always have to look and then test with the meter.\u00a0\u00a0 Pushing and probing around the meter, I could see that it was not working as it should.\u00a0 Time to order another part from Harbach, this time the relay and replacement resistor.\u00a0 Fifteen minutes later, the RY-200<\/a> was ordered.\u00a0 Progress would be halted for a few weeks due to a trip back east the following weekend.<\/p>\n After\u00a0 few weeks I had some time and I went back out to the the garage to work on the amp.\u00a0 I took about a dozen pictures of how everything was connected on the old relay, and then pulled it out, as well as the 2000 Ohm resistor, As the new relay has a new 4.7K 5W R-18 replacement.\u00a0 This resistor replaces the original R-18 (2K 7W).\u00a0 This resistor is changed due to a change in coil resistance of the relay from about 2.3K to 1.4K by the relay manufacturer.\u00a0 This will allow the proper amount of operating bias to be applied to the tubes during transmit (~ -2VDC).<\/p>\n I swapped out both the relay and the resistor, then went about connecting everything back up.\u00a0 About 50 minutes later, I had the case on and was back to the point I was a week ago with the radio and dummy load hooked up.<\/p>\n With the amp off I keyed the radio.<\/p>\n NO high SWR!\u00a0 Wahoo!<\/p>\n I can see the needle of the meter on the SB-200 moving about as well.\u00a0 Wahoo!<\/p>\n I quickly went through the steps in the manual and then fired up the amp.\u00a0 Again, keying the amp with the foot switch, I was able to use my key to put out a steady carrier and I adjusted the plate.\u00a0 ‘DIP the PLATE!’ I started out at 40W of carrier on 20m and started fiddling with the amplifier.\u00a0 Adjust the TUNE to the point where the plate voltage dips, while watching the meter on the SB-200,\u00a0 then quickly move to the LOAD adjustment and tune for max power, while observing the meter on the Bird 43 move.\u00a0 Unkey the amp after about 5 seconds and do it again, however this time more granular on the TUNE and LOAD adjustments.<\/p>\n Dip the plate with the TUNE knob, then adjust the LOAD for max power out – 450w on 1000W slug.<\/p><\/div>\n I did this for about the next 20 minutes on all the bands, first at 40w, then again at 60w.\u00a0 Ninety nine percent of what I have read in the forums and mail lists state that you do not need to run more than 60W of power to get the 10dB gain that this amp should provide.\u00a0 Sixty watts in should net 600W out, in theory.\u00a0 Sure, I could crank it up to 100W into the amp, but I bet I would be splattering all over the place when I get it off the dummy load and on the air.<\/p>\n So, with 60 watts, this was my net result, with the tubes that came with the amplifier.<\/p>\n Wired for 120V.<\/p>\n HV at rest 2300V<\/p>\n key down 1800V\u00a0 (and yes, the lights were dimming<\/em>)<\/p>\n 80 meters:\u00a0\u00a0\u00a0 400W<\/p>\n 40 meters:\u00a0\u00a0\u00a0 560W<\/p>\n 20 meters:\u00a0\u00a0\u00a0 500W<\/p>\n 15 meters:\u00a0\u00a0 440W<\/p>\n 10 meters:\u00a0\u00a0 300W<\/p>\n I am delighted with those results.\u00a0 I discovered for myself how touchy the adjustments are for 10M.\u00a0 Everyone online talk about this issue, and it is true. Very small movements make drastic changes.\u00a0 I might have to do something about that.\u00a0 (And now we are into the 95% I spoke about earlier…<\/em>)\u00a0 I was surprised 80 and 40 meters were not higher, but that could be the voltage drop, the age of the tubes, or even some resistors out of spec.\u00a0 However, for now I am excited.\u00a0 The magic smoke stayed in the rig, no funny smells, and it works as it should (or close) and I think the next step is getting it on the air.\u00a0 Wahoo! Well, After completing Part II, I thought I was well on my way to completing this SB-200 project.\u00a0 Well, I should say, ‘complete enough’ of the project, because Heathkits are never complete- the projects hang out in the 95% area of completion, as there is always a mod or 3 that you could do to […]<\/p>\n","protected":false},"author":1,"featured_media":255,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,50,6],"tags":[70,71,73,72,51],"class_list":["post-243","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-general-ham","category-sb-200","category-technology","tag-amplifier","tag-barn","tag-relay","tag-repair","tag-sb-200"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/posts\/243","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=243"}],"version-history":[{"count":7,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/posts\/243\/revisions"}],"predecessor-version":[{"id":257,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/posts\/243\/revisions\/257"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=\/wp\/v2\/media\/255"}],"wp:attachment":[{"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=243"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=243"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.n1rwy.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=243"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
\nI hear the relay engage.<\/p>\n![\"picture](\"https:\/\/www.n1rwy.org\/wp-content\/uploads\/2016\/12\/photo3-768x1024.jpg\")
![\"Bird](\"https:\/\/www.n1rwy.org\/wp-content\/uploads\/2016\/12\/photo1-768x1024.jpg\")
\n
\nBeyond the adjustment for 10m and some research on the 40 and 80m ‘low’ power, I want to add a muffin fan to the amplifier to help with cooling. (Again… back to 95%<\/em>).\u00a0 Excited to get it on the air for some tests.\u00a0 I might have to reach out to Steve, KD1O<\/a> back in Maine for some honest signal reports.<\/p>\n","protected":false},"excerpt":{"rendered":"