[Drakelist] Neutralization pre 1963 Handbook
Mike, The 1963 ARRL Handbook has the following which I have used on my TR3 when I owned it. They are speaking of a grid driven amp, but it is the same for a GG which is what Drake has in their final stage. I just used a receiver, but you can make the device if you care to, but be careful. 73, Ron WD8SBB The procedure in neutralizing is essentially the same for all types of tubes and circuits. The filament of the amplifer tube should be lighted and excitation from the preceding stage fed to the grid circuit. Both screen and plate voltage should be disconnected at the transmitter terminals. The immediate objective of the neutralizing process is reducing to a minimum the rf drive voltage fed from the input of the amplifier to its output circuit through the grid-plate capacitance of the tube. This is done by adjusting carefully, bit by bit, the neutralizing capacitor or link coils until an rf indicator in the output circuit reads minimum. The device in fig 6-22 makes a sensitive neutralization indicator. The link should be coupled to the output tank coil at the low potential or ground point. Care should be taken to make sure that the couple is loose enough at all times to prevent burning out the meter or the rectifier. The plate tank capacitor should be readjusted for maximum reading after each change in neutralizing. The grid-current meter may also be used as a neutralizing indicator. With plate and screen voltage removed as described above, there will be a change in grid current as the plate tank circuit is tuned through resonance. The neutralizing capacitor should be adjusted until this deflection is brought to minimum. As a final adjustment, plate and screen voltages should be applied and the neutralization capacitance adjusted to the point where minimum plate current, maximum grid current and maximum screen current occur simultaneously. An increase in grid current when the plate and circuit is tuned slight on the high frequency side of resonance indicates that the neutralizing capacitance is too small. If increase is on the low-frequency side the neutralizing capacitance is too large. When neutralization is complete, there should be a slight decrease in grid current on either side of resonance. 1n34 diode $-|- $ | | $ link coil C ---ma meter $--- | $ | | $- ASCII fig 6-22 circuit of sensitive neutralizing indicator. 1n34 is diode MA is 0-1 direct current millimeter and C is a .001 uf mica bypass capacitor. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake MN-2000
Can the MN-2000 handle a 6:1 SWR ? My feedline is coax and the highest SWR on my Hustler 6BTV is on 80 meters. And I have a MN-2000 and if it cant handle it what do you folks suggest? Thanks! 73 de Bill K9BuB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake MN-2000
Let me clarify. The antenna is tuned. I use it for MARS on 80 meters and that frequency is a 1.9:1 SWR but I would like to talk on my part of the band that my license allows and starting at 3.8Mhz my swr is 5.9:1 so I need a tuner. --- On Sat, 8/30/08, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: From: [EMAIL PROTECTED] [EMAIL PROTECTED] Subject: Re: [Drakelist] Drake MN-2000 To: [EMAIL PROTECTED] Date: Saturday, August 30, 2008, 6:34 PM In a message dated 8/30/2008 7:28:53 PM Eastern Daylight Time, [EMAIL PROTECTED] writes: Can the MN-2000 handle a 6:1 SWR ? My feedline is coax and the highest SWR on my Hustler 6BTV is on 80 meters. And I have a MN-2000 and if it cant handle it what do you folks suggest? Thanks! 73 de Bill K9BuB Hows about setting the antenna correctly, you should'nt even need a tuna! gl... Rich WA2RQY ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Neutralization pre 1963 Handbook
Ron - One detail. The Drake 4 Line finals are ALL grid driven, Class AB1, not grounded grid. Definitely be careful when disconnecting and reconnecting those Plate and Screen leads from the ceramic feedthrus. They WILL break and they ARE a pain to replace, even when you can find them! Also, don't rely solely on the bleeder resistors in the AC-4 to bring down the screen and plate supply voltages. 73, Garey - K4OAH Glen Allen, VA Ron Wagner wrote: Mike, The 1963 ARRL Handbook has the following which I have used on my TR3 when I owned it. They are speaking of a grid driven amp, but it is the same for a GG which is what Drake has in their final stage. I just used a receiver, but you can make the device if you care to, but be careful. 73, Ron WD8SBB The procedure in neutralizing is essentially the same for all types of tubes and circuits. The filament of the amplifer tube should be lighted and excitation from the preceding stage fed to the grid circuit. Both screen and plate voltage should be disconnected at the transmitter terminals. The immediate objective of the neutralizing process is reducing to a minimum the rf drive voltage fed from the input of the amplifier to its output circuit through the grid-plate capacitance of the tube. This is done by adjusting carefully, bit by bit, the neutralizing capacitor or link coils until an rf indicator in the output circuit reads minimum. The device in fig 6-22 makes a sensitive neutralization indicator. The link should be coupled to the output tank coil at the low potential or ground point. Care should be taken to make sure that the couple is loose enough at all times to prevent burning out the meter or the rectifier. The plate tank capacitor should be readjusted for maximum reading after each change in neutralizing. The grid-current meter may also be used as a neutralizing indicator. With plate and screen voltage removed as described above, there will be a change in grid current as the plate tank circuit is tuned through resonance. The neutralizing capacitor should be adjusted until this deflection is brought to minimum. As a final adjustment, plate and screen voltages should be applied and the neutralization capacitance adjusted to the point where minimum plate current, maximum grid current and maximum screen current occur simultaneously. An increase in grid current when the plate and circuit is tuned slight on the high frequency side of resonance indicates that the neutralizing capacitance is too small. If increase is on the low-frequency side the neutralizing capacitance is too large. When neutralization is complete, there should be a slight decrease in grid current on either side of resonance. 1n34 diode $-|- $ | | $ link coil C ---ma meter $--- | $ | | $- ASCII fig 6-22 circuit of sensitive neutralizing indicator. 1n34 is diode MA is 0-1 direct current millimeter and C is a .001 uf mica bypass capacitor. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
