Hi John, That very technique, i.e. the installation of a gas-fired bulb from the antenna terminal to ground, was used in the RCA AR-88 receiver of 1944...
http://www.shlrc.mq.edu.au/~robinson/museum/AR88cct.gif Apparently many of these rigs had occasion to operate physically close to QRO transmitting installations --- I guess the bulb was the WW2 equivalent of back-to-back diodes in the protection of receiver front ends... ~73~ Eddy VE3CUI - VE3XZ **************************************** ----- Original Message ----- From: "John Lyles" <[email protected]> To: <[email protected]> Sent: Monday, March 02, 2009 1:18 PM Subject: [AMRadio] gas tube protection of front end > Ne2 or Ne51 or whatever you have in it, are good for protecting hollow state front ends. As they ionize between 50 and 90 volts, they will conduct static buildup before it builds enough to open a coil in the front end. Although i have never heard of that happening either. Commercial receivers sometimes use more expensive devices like Claire makes, with a narrow specification for breakdown voltage. The capacitance of a neon bulb, before it ionizes, is low. For solid state RX, however, neons might not have low enough breakdown to protect fets, varactors, etc. You cannot simply put an MOV or transorb across a HF circuit as it will have a lot of capacitance. Sometimes back to back diodes are applied. Spark gaps and gas tubes still rule. > John > K5PRO > > > Message: 1 > > Date: Mon, 2 Mar 2009 00:57:58 +0000 (UTC) > > From: [email protected] > > Subject: [AMRadio] Receiver Antenna Input Question > > To: [email protected], [email protected], > > [email protected] > > Message-ID: > > <1524953191.2309561235955478082.javamail.r...@sz0147a.emeryville.ca.mail.com cast.net> > > > > Content-Type: text/plain; charset=utf-8 > > > > Would appreciate some advice here. I have a National NC-303 receiver that I'm restoring. I had a 75A-2 once that had a neon lamp (NE-2 ???) across the antenna input connection to supposedly act as a surge supressor for lightning, strong static charges?and strong rf energy from nearby transmitters. Is this a good idea? Does this really work? Is there a better device than a neon bulb? Appreciate any opinions, etc. 73, Bill, w0ng > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
