Re: [drakelist] OT coax contamination?
Peter Hoon [EMAIL PROTECTED] made an utterance to the drakelist gang -- Dan, You are correct, and I will likely do that next hamfest. In the mean time it just seems like an interesting puzzle. Guess it is the Engineer in me. Want to know what happened, what damage it did, etc. Ron, you can test the velocity factor of the contaminated coax you have and compare it to the expected value according to my MFJ-249 SWR Analyzer Instruction Manual as follows: Connect one end of your coax sample to the MFJ 249 or similar unit. Connect the other end with let us say 27 feet of coax to a fifty ohm resistor, between ctr and shield. You can coil up the coax on the floor. Measure precisely the length of your contaminated coax sample. Find the dip frequency using the 249 analyzer. For example, a 27 foot length has a dip frequency of about 7.3 Mhz. Divide 246 by the measured frequency. This gives you the free space one quarter wavelength in feet. Now, compute the velocity factor of your contaminated sample by dividing the free space one quarter wavelength by the actual feed line length. Compare the value you get for your contaminated sample with the velocity factor published in the transmission line chapter of the ARRL handbook (in my 1988 edition, it is on page 16-12). Of course, even if your sample tests good velocity factor wise, your contaminated sample could arc when you put power into it and cause problems. Peter VE1CHS I plan to see if the same thing has happened to the jumpers I have in service in the shack. It may give me another indication as to what happened. Maybe some time when I did some spray painting in the garage did something, or maybe the gasoline for the lawn mower vented enough to cause an issue. Yes I am a stange one, hi. :-) 73, Ron On Wed, 7 Dec 2005 [EMAIL PROTECTED] wrote: Ron, why take a chance on a product, that has changed and, will likely change further from original, with no telling what the end result of that change will be. -- 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 -- -- 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] OT coax contamination?
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- That doesn't sound quite right, but the MFJ instructions seem a little wierd. On Sun, 11 Dec 2005 09:31:29 -0700, Peter Hoon wrote: Connect one end of your coax sample to the MFJ 249 or similar unit. Connect the other end with let us say 27 feet of coax to a fifty ohm resistor, between ctr and shield. You can coil up the coax on the floor. You won't get ANY dip with the 50 ohm resistor at the end of the line. That would be a flat line. MFJ wants you to connect an open line to the analyser with a 50 ohm (Non-inductive) resistor in series with the center conductor at the antenna connector. Not sure why, I cut a 144.39 stub filter for my television line by just connecting an open line directly to the analyser; I didn't see any benefit to using the resistor. Measure precisely the length of your contaminated coax sample. Find the dip frequency using the 249 analyzer. For example, a 27 foot length has a dip frequency of about 7.3 Mhz. Start at the LOW end of the range and find the first dip. The line will dip at 1/4 wavelength and multiples thereof. -- Jim Shorney --.--Put complaints in this box jshorney (at) inebraska.com Ham Radio NU0C Lincoln, NE, USA EN10ps http://incolor.inetnebr.com/jshorney/ -- 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] 6HS6 replacement/equivalent
[EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I find myself with only 2 good 6HS6 spares - just wondering if there are replacements or equivalents for this tube or should I look for 6HS6 only. This is for my R-4B. Thanks! -- 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 --
Re: [drakelist] 6HS6 replacement/equivalent
The following tubes may be used as a Good substitute for a 6HS6 but NOT as an exact substitute. 6AG5 6AU6 6BA6 6CB6 My advice...Locate some more 6HS6 units. 73, Jay/AF2C At 02:43 PM 12/11/05 -0500, you wrote: [EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I find myself with only 2 good 6HS6 spares - just wondering if there are replacements or equivalents for this tube or should I look for 6HS6 only. This is for my R-4B. Thanks! -- 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 --
Re: [drakelist] 6HS6 replacement/equivalent
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Jason - Unfortunately, there isn't a good substitute for the 6HS6. The 6AU6A will work, but it's only about half the transconductance (gain) of the 6HS6. This can cause some difficulties with AGC and gain distribution in the receiver. They ARE getting expensive, probably a combination of their unique capabilities and small production quantities. The good news is that they are pretty reliable and long lived. I've only had to replace two over the years, one with an open filament and one that was just flat. One or two good spares, preferably RCA or Sylvania branded, will probably outlast the rest of the receiver and/or it's use to you. In a pinch, you can sub a 6AU6A, but 6HS6s aren't going to get any cheaper or more available! 73, Garey - K4OAH Atlanta Drake C-Line Service Manual http://www.k4oah.com [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I find myself with only 2 good 6HS6 spares - just wondering if there are replacements or equivalents for this tube or should I look for 6HS6 only. This is for my R-4B. Thanks! -- 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 --
Re: [drakelist] OT coax contamination?
I think that you can short one-end and using good GDO, form a small loop at one end and loosely couple the GDO by inserting it into loop measure it as though it is a quarter wave long, but at half the frequency. Use the following formula: V = (length in feet of the cable x frequency)/246 V= velocity factor Another method using the GDO: From CQ Magazine May 1974 here is another method: Measure the length of the coax carefully. Place a hairpin short at one end of the cable and a short loop between the shield and center conductor at the other end...The loop should be large enough to insert the GDO. If you can couple into a very small loop, the readings will be much better...Use of a large loop with show a slightly lower frequency on the GDO. Suppose that you are measuring 1ØØ feet of cable. Calculate what you believe the resonant frequency using a table of known values. Dip the cable. For our example the cable dips at 3.9 MHz The calculated resonant frequency is 4.Ø83 MHz (based on 1ØØft and a velocity factor of Ø.83) frequency = (492 x velocity factor)/ feet frequency = (492 x .83)/1ØØ = 4.Ø83 MHz Now using the described method, find the resonant frequency of the unknown cable an perform the following calculations: V = (feet x frequency of the dip)/492 = (1ØØ x 3.9)/492 = Ø.792 Again look for a loose coupling (shallow dip) I can see the MFJ method as a possibility. The 5Ø Ohm load provide purely resistive load at a fixed value. The meter relies on a 5Ø Ohm load. The method described in the magazine article, utilizing a GDO is not impedance dependent. BTW, the GDO should (after measurement are taken), be placed near a good receiver to obtain the exact frequency of the Dip. 73, Jay/AF2C At 12:14 PM 12/11/05 -0600, you wrote: Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- That doesn't sound quite right, but the MFJ instructions seem a little wierd. On Sun, 11 Dec 2005 09:31:29 -0700, Peter Hoon wrote: Connect one end of your coax sample to the MFJ 249 or similar unit. Connect the other end with let us say 27 feet of coax to a fifty ohm resistor, between ctr and shield. You can coil up the coax on the floor. You won't get ANY dip with the 50 ohm resistor at the end of the line. That would be a flat line. MFJ wants you to connect an open line to the analyser with a 50 ohm (Non-inductive) resistor in series with the center conductor at the antenna connector. Not sure why, I cut a 144.39 stub filter for my television line by just connecting an open line directly to the analyser; I didn't see any benefit to using the resistor. Measure precisely the length of your contaminated coax sample. Find the dip frequency using the 249 analyzer. For example, a 27 foot length has a dip frequency of about 7.3 Mhz. Start at the LOW end of the range and find the first dip. The line will dip at 1/4 wavelength and multiples thereof. -- Jim Shorney --.--Put complaints in this box jshorney (at) inebraska.com Ham Radio NU0C Lincoln, NE, USA EN10ps http://incolor.inetnebr.com/jshorney/ -- 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] 6HS6 replacement/equivalent
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Jay - Have you actually used any of those subs in an R-4B or other receiver? I'm curious, because I've not had much luck with any of them. In the Premixer stage they all give a slightly lower output but aren't too bad, but in the First Mixer the gain and AGC characteristics are altered significantly. Based on my experience, I would consider them fair subs at best! :-) 73, Garey - K4OAH Atlanta Drake C-Line Service Manual http://www.k4oah.com [EMAIL PROTECTED] wrote: The following tubes may be used as a Good substitute for a 6HS6 but *NOT* as an exact substitute. 6AG5 6AU6 6BA6 6CB6 My advice...Locate some more 6HS6 units. 73, Jay/AF2C At 02:43 PM 12/11/05 -0500, you wrote: [EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I find myself with only 2 good 6HS6 spares - just wondering if there are replacements or equivalents for this tube or should I look for 6HS6 only. This is for my R-4B. Thanks! -- 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 --
Re: [drakelist] 6HS6 replacement/equivalent
Garey - It's a matter of semantics. :-)) I usually rate them as EXACT, GOOD or Doesn't Exist. In a pinch, the substitutes listed will work, but certainly not as well as the 6HS6 which is far superior than the subs mentioned. Yes, I have tried them and do work with degraded performance...I'm an old tube swapper from way back. ;-) I have never seen a 6HS6 bite the dust. Again, just to feel safe, buy a spare or two...As I stated in my original message. I'm kinda partial to Sylvania, Mullard and Amperex. 73, Jay/AF2C At 04:04 PM 12/11/05 -0500, you wrote: Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Jay - Have you actually used any of those subs in an R-4B or other receiver? I'm curious, because I've not had much luck with any of them. In the Premixer stage they all give a slightly lower output but aren't too bad, but in the First Mixer the gain and AGC characteristics are altered significantly. Based on my experience, I would consider them fair subs at best! :-) 73, Garey - K4OAH Atlanta Drake C-Line Service Manual http://www.k4oah.com [EMAIL PROTECTED] wrote: The following tubes may be used as a Good substitute for a 6HS6 but *NOT* as an exact substitute. 6AG5 6AU6 6BA6 6CB6 My advice...Locate some more 6HS6 units. 73, Jay/AF2C At 02:43 PM 12/11/05 -0500, you wrote: [EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I find myself with only 2 good 6HS6 spares - just wondering if there are replacements or equivalents for this tube or should I look for 6HS6 only. This is for my R-4B. Thanks! -- 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 --
Re: [drakelist] 6HS6 replacement/equivalent
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Jay - OK, we agree I've only see two fail in the last 40+ years working with Drakes. One open filament and one just about no emission. There wasn't anything rattling around in the latter one, so don't really know what happened to it. It's the only modern tube that I recall going that dead and still have a lit filament! :-) I wonder if Heath had similar good luck with them.? Guess they were designed to run all day in a very hot TV set, so an R-4(any) was probably a vacation. Certainly a more reliable tube than the 6EJ7 !! 73, Garey - K4OAH Atlanta Drake C-Line Service Manual http://www.k4oah.com [EMAIL PROTECTED] wrote: Garey - It's a matter of semantics. :-)) I usually rate them as EXACT, GOOD or Doesn't Exist. In a pinch, the substitutes listed will work, but certainly not as well as the 6HS6 which is far superior than the subs mentioned. Yes, I have tried them and do work with degraded performance...I'm an old tube swapper from way back. ;-) I have never seen a 6HS6 bite the dust. Again, just to feel safe, buy a spare or two...As I stated in my original message. I'm kinda partial to Sylvania, Mullard and Amperex. 73, Jay/AF2C At 04:04 PM 12/11/05 -0500, you wrote: Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Jay - Have you actually used any of those subs in an R-4B or other receiver? I'm curious, because I've not had much luck with any of them. In the Premixer stage they all give a slightly lower output but aren't too bad, but in the First Mixer the gain and AGC characteristics are altered significantly. Based on my experience, I would consider them fair subs at best! :-) 73, Garey - K4OAH Atlanta Drake C-Line Service Manual http://www.k4oah.com http://www.k4oah.com/ [EMAIL PROTECTED] wrote: The following tubes may be used as a Good substitute for a 6HS6 but *NOT* as an exact substitute. 6AG5 6AU6 6BA6 6CB6 My advice...Locate some more 6HS6 units. 73, Jay/AF2C At 02:43 PM 12/11/05 -0500, you wrote: [EMAIL PROTECTED] made an utterance to the drakelist gang -- hi, I find myself with only 2 good 6HS6 spares - just wondering if there are replacements or equivalents for this tube or should I look for 6HS6 only. This is for my R-4B. Thanks! -- 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 --
Re: [drakelist] OT coax contamination?
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Sun, 11 Dec 2005 15:36:01 -0500, [EMAIL PROTECTED] wrote: I can see the MFJ method as a possibility. The 5 Ohm load provide purely resistive load at a fixed value. The meter relies on a 5 Ohm load. The method described in the magazine article, utilizing a GDO is not impedance dependent. I think the 50 ohm resistor in series is to allow calculating the velocity factor of lines that are other than 50 ohm characteristuc impedance. With a 1/4 wave open line, the dip would appear at 50 ohms on the analyser. If the line is 50 ohms, the resistor can be elimintated and the dip will be at 0 ohms. This worked for my 144.39 stub filter. Actually, I'm still not at all sure that the series resistor is needed at all. An open line, regardless of it's impedance, will reflect a short at it's 1/4 wave resonant frequency. 0 ohms is 0 ohms, regardless of the source impedance of whatever is feeding it. Maybe someone with more education than I am can enlighten me. -- Jim Shorney --.--Put complaints in this box jshorney (at) inebraska.com Ham Radio NU0C Lincoln, NE, USA EN10ps http://incolor.inetnebr.com/jshorney/ -- 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 --
