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41. Re: [Amps] SB-1000 160 m power down (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Thu, 22 Dec 2011 15:27:27 +0900; Thanks to all the people who have gave me advice the 160 m power-down problems have been solved. The cause was the second filter resonance. I have added a second B+ filter at the cold-end of the plat; /archives//html/Amps/2011-12/msg00188.html (8,134 bytes)
42. Re: [Amps] RF coupling to 8877 filaments? (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Tue, 13 Mar 2012 08:45:38 +0900; hi Mike and all The goal of the filament choke is to prevent a feedthrough - leakage - from the cathode to the filament transformer, and the break down between cathode and filaments, if filaments hav; /archives//html/Amps/2012-03/msg00146.html (7,565 bytes)
43. Re: [Amps] Coax for MHV connectors? (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Mon, 25 Jun 2012 13:38:51 +0900; hi all I know the military HV connector with interlock pins is the best. I am using HN and RG-8/U for my HV cable connecting HVPS and RF deck in a standard rack. Ground of the HN cable/connector conn; /archives//html/Amps/2012-06/msg00405.html (8,323 bytes)
44. Re: [Amps] Heathkit SB-1000 Arcing (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Fri, 30 Nov 2012 11:03:32 +0900; hi gents. I also have one. If the ark occur at the stand-by state (not TXing) you should check HV+ as well as the tube itself. The tube can cause ark inside especially when it is NOS. If it is the ca; /archives//html/Amps/2012-12/msg00004.html (8,897 bytes)
45. Re: [Amps] Air Variable Spacing Question (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Thu, 6 Dec 2012 13:29:15 +0900; Hi Jim san The 0.080" gap is equal to 2.0 mm. I think it is not enough for such a HP amp as your opinion. It is said that, using a safety factor of 200 % an air variable capacitor with a gap of 1mm s; /archives//html/Amps/2012-12/msg00023.html (8,597 bytes)
46. Re: [Amps] Plate choke explodes (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Sat, 13 Apr 2013 08:12:34 +0900; Hi all Possibly high RF current on the plate RFC - meaning it has a hole on 50 MHz. I have burnt a plate RFC in my 6m RF deck because of parasitic oscillation around 60 MHz. But 8877 must be quite st; /archives//html/Amps/2013-04/msg00095.html (7,743 bytes)
47. Re: [Amps] Plate choke explodes (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Sun, 14 Apr 2013 07:09:36 +0900; Generally small plate RFC can burn with de-tune of the plate circuit Or 1. two different chokes had similar holes on 50 MHz. 2. the tube oscillates with significant power. 3. the tube has troubles su; /archives//html/Amps/2013-04/msg00108.html (10,468 bytes)
48. Re: [Amps] HV resistor source (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Wed, 17 Apr 2013 18:28:11 +0900; Yes it is. Arc inside tube or HV touch to the ground make a large surge current. Without the series resistor tube, power supply diodes, meter circuits may be damaged. Or sometimes itself can burn or; /archives//html/Amps/2013-04/msg00152.html (7,747 bytes)
49. Re: [Amps] HV resistor source (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Thu, 18 Apr 2013 09:20:58 +0900; A larger protection resistor is better because of its sustainability against any surge current. A small watt resistor can be used but it will act as a fuse. I again recommend 30-50 ohm 25-100 watt re; /archives//html/Amps/2013-04/msg00167.html (8,833 bytes)
50. Re: [Amps] Discrepencies in Pi-net calculators (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Thu, 21 Nov 2013 07:08:05 +0900; Hi Steve I am using fomula: Xc1 = Zi/Q Xc2 = Zo x rt(Zi/Zo / (Q^2 + 1 - Zi/Zo)) XL = (QZi + (ZiZo/Xc2))/(Q^2+1) and with Zi = 50, Zo = 135, f = 28.03 and Q = 2.7 one can obtain C1 = 306.6 pF C2 = 194; /archives//html/Amps/2013-11/msg00397.html (9,233 bytes)
51. Re: [Amps] HV Diodes (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Wed, 8 Oct 2014 19:13:52 +0900; hi George-san and all I think HV6-1 is equivalent to GI HVPR10-MX12. I have measured forward voltages of these diode modules using a CVCC power supply with 100-mA current. Assuming each of the diode; /archives//html/Amps/2014-10/msg00021.html (7,595 bytes)
52. Re: [Amps] 3CX1200 tubes (score: 1): Author: "Han Higasa" <higasa@plum.ocn.ne.jp>; Date: Thu, 2 Apr 2015 08:45:50 +0900; hi Randy san 3CX1200A7 and -D7 need neutralization for stable operation on HF and 6 m, while -Z7 runs well without neut. Neutralization of the A7 and D7 is easy using trifiller coil on a small ferrit; /archives//html/Amps/2015-04/msg00021.html (8,614 bytes)

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