[AMRadio] capacitors for tank circuits
Berrie: The size of the spilt stator capacitor that you are looking for may need to be determined by the voltage and current that you intend to run, The ratio of I:E determines the capacitance There are charts in the handbooks for this purpose. Be sure to consider that you are doing push pull with a balanced tank circuit as the required capacitance is only a quarter of that required for non-balanced. The voltage will determine the needed spacing of the plates. If you raise the tank capacitor above the chassis on insulators and connect the rotor to B+ you can get by with less spacing but you will need to use and insulated coupler to the knob shaft and be sure the knob shaft is grounded for safety. You can also accomplished the same thing by using two large RF chokes, one per tube, and capacitive coupling the RF to the tank circuit as is done in most PI net circuits. This way the plate tank cap can be mounted to chassis and the RF choke at the center of the tank coil can be grounded. The idea is to not have a DC + modulation voltage across the plates of the tank capacitor but just RF voltage. Capacitive coupling, as was just described, is a neat way to do this but it requires the very large long RF chokes and good coupling capacitors. I would suggest looking for 812s for the final and modulate with 811As. I think the 811A is good to 1500 Volts at Zero bias for modulators but can run 2000 if a regulated bias supply is used. The 812s, for a push pull final, are easy to drive and easy to light up. If you're skeptical of their size then use 4 of them. The nice thing about a single band rig, is that you can just wind your coils and bolt or solder them into place. Making a adjustable output link may get creative though. Good Luck John, WA5BXO __ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/amradio@mailman.qth.net/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] capacitors
Original Message From: Rick Brashear <[EMAIL PROTECTED]> Does anyone have an abundance of .47 or .5 tubular capacitors? Not disc. I need several 200 vdc and several 450 vdc for a project I am soon to be working on. Orange Drop or similar would be great. Cash paid. Thanks, Rick/K5IAR Reply by Jim, WD5JKO: Rick, Look at Ebay item 200163665158. These are Mylar .47 mfd @ 1kv where the QTY=10 for $9.99 + shipping. Jim JKO __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] capacitors
Does anyone have an abundance of .47 or .5 tubular capacitors? Not disc. I need several 200 vdc and several 450 vdc for a project I am soon to be working on. Orange Drop or similar would be great. Cash paid. Thanks, Rick/K5IAR __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
RE: [AMRadio] capacitors
Thanks to all for your help with my mica capacitor argument. It seems the silver mica won hands down from all of the personal and public email I received. That means I won the argument! Man, that's a first. My opponent was adamant about "film" capacitors and while I agree in some instances they would be just fine in general I think it's a safer bet to use silver mica. Thanks everyone! Rick/K5IAR __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] capacitors
- Original Message - Subject: [AMRadio] capacitors Date: Thu, September 13, 2007 10:52 From: "Rick Brashear" <[EMAIL PROTECTED]> > What is the general consensus here on the reflector as to which type of > capacitor should be used in place of the old molded mica capacitors? > If it's really a mica, I'd replace it with a silver mica, or if you need a voltage rating beyond 500V, use a "snubber capacitor" (which I THINK is a silver-mica, made by Cornell-Dublier, sold by Mouser. Usual disclaimers apply). If it's one of those mica look-alike wannabes, but really a wax-paber capacitor (typically vales .01uF and above), replace it with a mylar cap. -Larry/NE1S __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
RE: [AMRadio] capacitors
Do you have trouble finding the proper capacitance in higher voltages, 600 wvdc and up? Thanks, Rick/K5IAR From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W6OM I use new Silver Mica Capacitors and have never had any issues with them. Tolerances are tighter, case is improved and they are inexpensive. One hams opinion... __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] capacitors
I use new Silver Mica Capacitors and have never had any issues with them. Tolerances are tighter, case is improved and they are inexpensive. One hams opinion... - Original Message - From: "Rick Brashear" <[EMAIL PROTECTED]> To: "'Discussion of AM Radio in the Amateur Service'" Sent: Thursday, September 13, 2007 7:52 AM Subject: [AMRadio] capacitors What is the general consensus here on the reflector as to which type of capacitor should be used in place of the old molded mica capacitors? ...I hope to settle an argument with your results. :-) Thanks, Rick/K5IAR __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body. __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
[AMRadio] capacitors
What is the general consensus here on the reflector as to which type of capacitor should be used in place of the old molded mica capacitors? ...I hope to settle an argument with your results. :-) Thanks, Rick/K5IAR __ Our Main Website: http://www.amfone.net AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
Re: [AMRadio] Capacitors
What type of capacitors I should use to replace the paper Astron and West-Cap capacitors in the rf strip on the sp-600? I have a good stock of new Sprague Orange Drops or I can use ceramic disk. I don't want to have to do this again. Of course, at my age, it's doubtful that will happen! I tend to use orange drops to replace old wax tubular paper caps, and silver micas to replace mica caps. Disc ceramics have always worked for me to replace paper caps, but I prefer orange drops. I use disc ceramics to replace original disc ceramics, but never to permanently replace micas. From my experience, disc ceramics are the most failure-prone of all. The little red micas in older Collins gear tend to go leaky over time. I couldn't count the number of these I have replaced in my two 75A-4's and ones I have repaired for other people. One problem I have run into is that many of the standard values of micas and silver micas are getting hard to find. Like everything else offered on the commercial market, the variety of choice is steadily dwindling. For example, a couple of years ago I needed a 120 pf mica, or some specific value near that (I may not have remembered these figures correctly - and my computer is not out in the shack, but you should get the idea). I could find a 100 pf and a 110pf, or a 140 pf, but the exact value was no longer listed in any of the catalogues, and the local electronics store said they couldn't order that value for me. Someone sent me a couple of the values I needed, that they had on hand. They said they had got them from Mouser Electronics. When repairing a piece of antique gear that I want to look authentic and original, I gut the old wax paper caps, and refill them with orange drops, and re-pour melted wax to seal the modern component inside. I usually keep the original wire leads whenever possible, since modern caps tend to have smaller gauge wire leads than the older caps. I never throw away old wax caps, but keep them on hand in a special box just for that purpose in case I need them. I have done the same with large rectangular paper and electrolytics. But for something like the 75A-4, I just drop in new components to replace failed ones. Don k4kyv __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Capacitors
According to Hoyle (was he a ham?) use ceramic capacitors for bypass in the front end of the receiver (RF, oscillator and mixer stages) and use tubulars for bypass and coupling in the IF, bfo, audio and other low frequency stages. I've used tubulars throughout, too, and they work fine. I am sure ceramics would also, just can't bring myself to put those flimsy things throughout an old receiver. In fact, I've taken them out when found as replacements. Long ago, heard that the inductance inherent in tubular capacitors was factored-in when designing RF coils, but I seriously doubt it. When replacing components, use the original gound points and component placement. 73 de Bill, AB6MT [EMAIL PROTECTED] - Original Message - From: Rick Brashear To: AMRadio@mailman.qth.net Sent: Friday, December 29, 2006 8:15 PM Subject: [AMRadio] Capacitors What type of capacitors I should use to replace the paper Astron and West-Cap capacitors in the rf strip on the sp-600? I have a good stock of new Sprague Orange Drops or I can use ceramic disk. I don't want to have to do this again. Of course, at my age, it's doubtful that will happen! Thanks... Rick/K5IZ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Capacitors
Rick Brashear wrote: What type of capacitors I should use to replace the paper Astron and West-Cap capacitors in the rf strip on the sp-600? I have a good stock of new Sprague Orange Drops or I can use ceramic disk. I don't want to have to do this again. Of course, at my age, it's doubtful that will happen! I'd offer, Rick, that whatever you have in stock, is going to be a better replacement than what's in the ancient SP-600. That said, whatever is easier to replace 'em with, as long as the capacitance and voltage match. -- 73 __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Capacitors
What type of capacitors I should use to replace the paper Astron and West-Cap capacitors in the rf strip on the sp-600? I have a good stock of new Sprague Orange Drops or I can use ceramic disk. I don't want to have to do this again. Of course, at my age, it's doubtful that will happen! Thanks... Rick/K5IZ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] capacitors
Has anyone extensively used the Fair Radio Xicon Polypropylene capacitors? I have let my stock get dangerously low and want to place an order, but I can't remember if I've used these for replacement of old paper caps. Any advice? Thanks, Rick __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Capacitors
Does anyone know where 2% tolerance film capacitors are available? I need a couple of the .02, 2 mfd versions. I also need .018 and .0047 all at 400 volts or greater. 73 Jim W5JO From [EMAIL PROTECTED] Wed Jul 20 17:13:40 2005 Return-Path: <[EMAIL PROTECTED]> X-Original-To: amradio@mailman.qth.net Delivered-To: amradio@mailman.qth.net Received: from ms-smtp-03-eri0.texas.rr.com (ms-smtp-03.texas.rr.com [24.93.47.42]) by mailman.qth.net (Postfix) with ESMTP id B6836859C22 for ; Wed, 20 Jul 2005 17:13:28 -0400 (EDT) Received: from [127.0.0.1] (cpe-24-160-159-156.satx.res.rr.com [24.160.159.156]) by ms-smtp-03-eri0.texas.rr.com (8.12.10/8.12.7) with ESMTP id j6KL0URb001516 for ; Wed, 20 Jul 2005 16:00:32 -0500 (CDT) Message-ID: <[EMAIL PROTECTED]> Date: Wed, 20 Jul 2005 16:00:20 -0500 From: Geoff <[EMAIL PROTECTED]> Organization: Every day of Freedom is a good day to thank a Veteran. User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Discussion of AM Radio Subject: Re: [AMRadio] Capacitors References: <[EMAIL PROTECTED]> In-Reply-To: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Symantec AntiVirus Scan Engine X-BeenThere: amradio@mailman.qth.net X-Mailman-Version: 2.1.4 Precedence: list Reply-To: Discussion of AM Radio List-Id: Discussion of AM Radio List-Unsubscribe: <http://mailman.qth.net/mailman/listinfo/amradio>, <mailto:[EMAIL PROTECTED]> List-Archive: <http://mailman.qth.net/mailman/private/amradio> List-Post: <mailto:amradio@mailman.qth.net> List-Help: <mailto:[EMAIL PROTECTED]> List-Subscribe: <http://mailman.qth.net/mailman/listinfo/amradio>, <mailto:[EMAIL PROTECTED]> X-List-Received-Date: Wed, 20 Jul 2005 21:13:40 - Jim Wilhite wrote: >Does anyone know where 2% tolerance film capacitors are available? I need a >couple of the .02, 2 mfd versions. I also need .018 and .0047 all at 400 >volts or greater. > > > http://heh.pl/&G0 <http://heh.pl/&G0> 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Capacitors
Hi Ron; Maybe you can make one. Get some 10 ohm, 1/2 watt resistors and try different combinations of 2 in parallel until you achieve 5.1 ohms. Usually, metering resistors are 1%. The .1 is well within the 5% tolerance, so you could use just a 5 ohm resistor. It could be that 5 ohms was the design value but they used 5.1 because that is a standard value. Good luck. 73, Ed Richards K6UUZ On Wed, 4 Aug 2004 05:24:03 EDT [EMAIL PROTECTED] writes: > Tnx to all on the Capactor info...the Viking 2 is getting close to > power up > tickling time...I need a 5.1 Ohm 5% 1 watt resistor,found one > cracked.this > resister is a meter shunt resistor for the 6au6 Oscillator..Any one > have one?..Tnx > es 73's Ron W6MAU > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net >
[AMRadio] Capacitors
Tnx to all on the Capactor info...the Viking 2 is getting close to power up tickling time...I need a 5.1 Ohm 5% 1 watt resistor,found one cracked.this resister is a meter shunt resistor for the 6au6 Oscillator..Any one have one?..Tnx es 73's Ron W6MAU
