Re: [drakelist] Soft start solution for 110v operation
[EMAIL PROTECTED] made an utterance to the drakelist gang -- Various sizes of inrush limiters are available from RF Parts... -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
Re: [drakelist] Soft start solution for 110v operation
[EMAIL PROTECTED] made an utterance to the drakelist gang -- On Wed, 14 Dec 2005, Jim Shorney wrote: All this is partially moot until he's accepting orders but i'd like to prepare now - i'm open to other soft start inrush limiter ideas as well. You can use NTC (negative temperature coefficient) inrush limiters such as what is used in virtually every PC power supply these days - they usually look like a big black ceramic capacitor. The ones in PC power supplies are sized just about right for tube amatuer gear actually; I My only concern with thermisters is they increase HV transformer primary winding ESR and slop the HV regulation. At 50W load for a typical R-4 the voltage drop by the thermister probably isn't much, but 400W load for the AC-4 would probably reach the maximum permissible 10% voltage drop range adding to frequency drift during key down. 100VAC is too low methinks ;-) I experimented with one of them for feeding my AC-4/T-4XB and the panel lights dimmed enough to make me nervous with 80W PEP CW output. liberated one from a dead PC supply and installed it in my AC4, and there was a noticable reduction in the turn-on thump. How much dimming effect on the panel lights do you notice with the part you used? I may have one that isn't suited for that much current draw. Hopefully Harbach will be accepting orders soon - a few of those SS-100 jobs will make my day! -- 73 Jason N1SU http://n1su.com/ -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
[drakelist] Soft start solution for 120v operation
Laird Tom N [EMAIL PROTECTED] made an utterance to the drakelist gang -- Why wait? You can make one with a relay and a few other parts... Tom WC9M Molime, IL. -- My only concern with thermisters is they increase HV transformer primary winding ESR and slop the HV regulation. At 50W load for a typical R-4 the voltage drop by the thermister probably isn't much, but 400W load for the AC-4 would probably reach the maximum permissible 10% voltage drop range adding to frequency drift during key down. 100VAC is too low methinks; I experimented with one of them for feeding my AC-4/T-4XB and the panel lights dimmed enough to make me nervous with 80W PEP CW output. Hopefully Harbach will be accepting orders soon - a few of those SS-100 jobs will make my day! 73 Jason N1SU -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
RE: [drakelist] 2-NT Sidetone
Frankly, I never did understand why sidetones were that high or why most are still not adjustable. I can't actually remember preferring to listen to CW at a higher pitch even when I was young so I'm not sure why sidetones have traditionally been so high. Eric KE6US www.ke6us.com From: Mike Williams [mailto:[EMAIL PROTECTED] Sent: Thursday, December 15, 2005 2:57 PMTo: EricJ; '[EMAIL PROTECTED] Zerobeat. Net'Subject: Re: [drakelist] 2-NT Sidetone Hey Eric, some of us youngsters prefer the 600 Hz tones too! Mike W4DL - Original Message - From: EricJ To: '[EMAIL PROTECTED] Zerobeat. Net' Sent: Thursday, December 15, 2005 1:39 AM Subject: [drakelist] 2-NT Sidetone I recently acquired a 2-NT to go with my 2-B and 2-C. I work CW exclusively so it has all the features I care about (except a VFO. hi). When this rig was new, I was 24 years old. My young ears had no problem with the 1 kc sidetone that many commercial rigs including the 2-NT use. Now almost 40 years later I can'dt that that screeching sidetone. I've set the offset on my QRP rigs for about 600 Hz, and I prefer my sidetone to be around that also. A quick look at the schematic shows that increaseing C43, C44 and C45 would decrease the frequency. Using Spectrogram I measured the original sidetone at 966 Hz. An 0.005 uf cap in parallel with these 3 caps brought it down to 650 Hz.Close enough.I didn't have any on hand, but 0.0056 might have put it on the money. I soldered the caps on the back side of the PCB. It's much easier and they can be easily removed if you want to reverse the mod to sell the rig. A lot of older hams have found that a lower offset or sidetone is more comfortable. Some even go to 500 Hz or so. This mod is easy to do on the 2-NT and something comparable could probably be done on other rigs. There are photograps of the mod and my "2-Line" station at: http://www.ke6us/boatanchors.htm Eric KE6US www.ke6us.com
[drakelist] AC-3 and linear amp
Jason Buchanan [EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I need to control my L4 and key it from an AC-3 - any tips for using pins 5 and 8 on the cinch connector or is it as straightforward as it looks? Pins 5 and 8 do not appear to be grounded or tied to any other circuit... but just wanted to ask everyone just to be certain. I'm planning on using an RCA female connector at the cinch connector, and use a standard male-mail RCA patch cable to run the keying circuit to a switchbox I made that ties into the L4. thanks, Jason N1SU -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
[drakelist] Fw: TR7 pre-driver board problem
Floyd Sense [EMAIL PROTECTED] made an utterance to the drakelist gang -- I'm just about there with my TR7 restoration, but have one more elusive problem. I've got the later pre-driver board with the MRF476. After running CW for a while at 100W out, the output drops off and eventually goes to about zero. If I let it sit for a while, everything is OK again. I traced the problem to the MRF476 - when it happens the heatsink is very hot. If I cool it down with a blast of cooling spray, I have full output again until it gets hot. I found the problem described pretty well in the document by VE3EFJ titled: Drake Mods, TR7 Mods. His solution is to improve the bias on the transistor by inserting a bundle of three paralleled 1.8 ohm 1/8 watt resistors. I read somewhere else that one shouldn't use this approach. Has anyone else had this problem and fixed it with the suggested bias change? I really don't see any other option at this point. I've touched up the solder joints on everything in the bias network for that transistor and no change in behavior. 73, Floyd - K8AC -- Submissions:drakelist@www.zerobeat.net Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
