Re: [drakelist] Pondering RF Feedback (TR7/SP75)
When and where to ground is not as simple as it sounds at first thought.? Depending on circuit design, several grounding schemes for microphones might have to be tried to ensure proper shielding while at the same time not creating a ground loop.? Too, ferrite beads on each and every lead going to/from the rig might help. Just some random thoughts from a fellow Drake enthusiast... -Original Message- From: Jim Shorney [EMAIL PROTECTED] To: drakelist@zerobeat.net drakelist@zerobeat.net Sent: Wed, 2 Jul 2008 10:35 pm Subject: [drakelist] Pondering RF Feedback (TR7/SP75) Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- Some readers may recall that last year I was plagued by RF feedback at Field Day with the TR7/SP75 combination. Careful balancing of the mic gain and SP75 input and output levels could eliminate it most of the time, but not always. This year, I connected a ground strap from the SP75 to the TR7 chassis, as was suggested here. Well, that helped quite a bit. However, I was still seeing some RF feedback this year. It was happening with the Yagi (4-el 20 meter monoband) pointed generally southwesterly, which would have been pretty much over my head. As usual, were stationed in an EMCOMM trailer on a concrete parking lot, with no station ground available. The feedback could be mostly eliminated, depending on the actual position of the Yagi, by reducing the TR7 mic gain. I couldn't nail down exactly where it was getting in, but it seemed to have something to do with the microphone wiring - a Telex Echelon 150 aircraft active noise-cancelling headset with a homebrew interface box. The box was solid aluminum, mic cable to the SP75 was RG-174/U coax, and power for the ANC amplifier and mic bias was well bypassed. Sort of a puzzler. Then I found this surfing the web: http://www.audiosystemsgroup.com/RFI-Ham.pdf This may be old news to some of you, but what caught my eye was the author's description of what is called the Pin 1 problem. I recalled from having been inside these boxen that the mic ground connection inside both the TR7 and the SP75 is not tied to the chassis at the point of entry, but rather, is wired to the circuit board. According to the referenced article, this is bad. I've made wiring changes to both the TR7 and SP75 to establish proper grounding, as described in the article. There is also a tech note on Heil's web site regarding this problem: http://www.heilsound.com/amateur/tips/rfi_removal_mics.htm Heil provides a method of grounding at the mic connector that is pretty easy, but I have a lot of microphones and I like to try out different things. It seems possible that this may be where my feedback was entering, but I have no way of duplicating the Field Day conditions at home (and I doubt the radio club will want to drag out the trailer, Yagi, and tower just to test my rig). I don't recall ever seeing this sort of RF feedback at home, so it will have to wait for next year to test out the Pin 1 problem theory. I'm thinking I will take along some snap-on ferrite chokes next time as well - or maybe I can get the club to add some to the Field Day kit. Any thoughts from the gallery? 73 -Jim NU0C (BTW, the Echelon headset knocked the generator noise right out of the headphones...) -- Submissions:drakelist@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] Antenna question
Hi all, For those with experience in regards to dipole and inverted v antennas. I do not have enough length available for an 80 M dipoleI do however have enough room to run to wires from our chimney into my back yard with about 92 ft one way and 95 ft plus at another angle. This would wind up being almost a horizontal V with about 80-90 ft between the ends. All the book learning says 60 to 120 degree anglesbut Yes I know try it Carl WD8NHK BTW I have probably got the only original never used T4 front panels (2) (unpunched) and a complete chassis and cabinet for same. This is just the sheet metal folks. Anyone interested ? **Gas prices getting you down? Search AOL Autos for fuel-efficient used cars. (http://autos.aol.com/used?ncid=aolaut000507)
Re: [drakelist] Antenna question
[EMAIL PROTECTED] made an utterance to the drakelist gang -- Hi Carl, If you stretch it out as a dipole in the longest space avaliable, why not let the ends, about 15 ft each, droop down? The ends contribute much less to the radiation than does the center section. I've been doing this for yrs, in several locations. I suspect it's better than an inverted V, it keeps the more important center section at a higher elevation. YMMV 73, Al, W8UT [EMAIL PROTECTED] wrote: Hi all, For those with experience in regards to dipole and inverted v antennas. I do not have enough length available for an 80 M dipoleI do however have enough room to run to wires from our chimney into my back yard with about 92 ft one way and 95 ft plus at another angle. This would wind up being almost a horizontal V with about 80-90 ft between the ends. All the book learning says 60 to 120 degree anglesbut Yes I know try it Carl WD8NHK BTW I have probably got the only original never used T4 front panels (2) (unpunched) and a complete chassis and cabinet for same. This is just the sheet metal folks. Anyone interested ? **Gas prices getting you down? Search AOL Autos for fuel-efficient used cars. (http://autos.aol.com/used?ncid=aolaut000507) -- Submissions:drakelist@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] Drake Twins On CW
Good Day All, I had a real treat here the past few days, setting up operating my T-4X transmitter R-4 receiver beneath the gazebo in the backyard, working Field Day Canada Day out in the fresh air on CW... What a wonderful pair of rigs for CW --- they really complement each other, and in more ways than one! I'd never had the T-4X even on before, until this past weekend (I acquired both rigs last December), and was quite impressed with it... I had no luck getting the rig to operate on 'phone, though...I guess I'll have to play around with the wires coming out the base of the amplified D-104 some more, before I try to get into the rig itself (I just HATE those amplified mics!). The PTT seems to work A-OK --- there's just no audio! Anyway, so far, as a CW station, all I have to say (again!) is, WHERE HAVE THESE RIGS BEEN ALL OF MY LIFE...?! Hi Hi. They're wonderful... ~73~ Eddy VE3CUI - VE3XZ
Re: [drakelist] Pondering RF Feedback (TR7/SP75)
[EMAIL PROTECTED] made an utterance to the drakelist gang -- I have also grounded my speech processors and other audio peripherals in this fashion. Additiionally, Drake published a bulletin regarding the bypassing of the PS7's AUX 12v output connector with a .01uF disk cap. (This was noted to be of concern when powering an SP75 from the PS7.) All of my PS7s have been thusly equipped...and have had no RF feedback problems since. 73 - Fred, N8YX -- Submissions:drakelist@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] Pondering RF Feedback (TR7/SP75)
Dieter Horst [EMAIL PROTECTED] made an utterance to the drakelist gang -- I agree with the ferrite idea. Whenever I go to the club station DL0AO for a major contest, I have a few ferrites with me. And they did help a lot in the past. Not only RF pickup in Mics and Headphones but also lots of computer problems like strangely behaving keyboards, mice etc. can be cured. At the last meeting of the Bavarian Contest Club a presentation was given on this subject by Hans DK3YD. The slides can be found here: http://www.bavarian-contest-club.de/storage/med/papers/linden2008/79_Linden2008_dk3yd.pdf (Sorry, all in German but you can see from the pictures how the ferrites are mounted. I may help with a translation if needed.) 73, Dieter DL5RDO When and where to ground is not as simple as it sounds at first thought.? Depending on circuit design, several grounding schemes for microphones might have to be tried to ensure proper shielding while at the same time not creating a ground loop.? Too, ferrite beads on each and every lead going to/from the rig might help. Just some random thoughts from a fellow Drake enthusiast... -Original Message- From: Jim Shorney [EMAIL PROTECTED] To: drakelist@zerobeat.net drakelist@zerobeat.net Sent: Wed, 2 Jul 2008 10:35 pm Subject: [drakelist] Pondering RF Feedback (TR7/SP75) Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- Some readers may recall that last year I was plagued by RF feedback at Field Day with the TR7/SP75 combination. Careful balancing of the mic gain and SP75 input and output levels could eliminate it most of the time, but not always. This year, I connected a ground strap from the SP75 to the TR7 chassis, as was suggested here. Well, that helped quite a bit. However, I was still seeing some RF feedback this year. It was happening with the Yagi (4-el 20 meter monoband) pointed generally southwesterly, which would have been pretty much over my head. As usual, were stationed in an EMCOMM trailer on a concrete parking lot, with no station ground available. The feedback could be mostly eliminated, depending on the actual position of the Yagi, by reducing the TR7 mic gain. I couldn't nail down exactly where it was getting in, but it seemed to have something to do with the microphone wiring - a Telex Echelon 150 aircraft active noise-cancelling headset with a homebrew interface box. The box was solid aluminum, mic cable to the SP75 was RG-174/U coax, and power for the ANC amplifier and mic bias was well bypassed. Sort of a puzzler. Then I found this surfing the web: http://www.audiosystemsgroup.com/RFI-Ham.pdf This may be old news to some of you, but what caught my eye was the author's description of what is called the Pin 1 problem. I recalled from having been inside these boxen that the mic ground connection inside both the TR7 and the SP75 is not tied to the chassis at the point of entry, but rather, is wired to the circuit board. According to the referenced article, this is bad. I've made wiring changes to both the TR7 and SP75 to establish proper grounding, as described in the article. There is also a tech note on Heil's web site regarding this problem: http://www.heilsound.com/amateur/tips/rfi_removal_mics.htm Heil provides a method of grounding at the mic connector that is pretty easy, but I have a lot of microphones and I like to try out different things. It seems possible that this may be where my feedback was entering, but I have no way of duplicating the Field Day conditions at home (and I doubt the radio club will want to drag out the trailer, Yagi, and tower just to test my rig). I don't recall ever seeing this sort of RF feedback at home, so it will have to wait for next year to test out the Pin 1 problem theory. I'm thinking I will take along some snap-on ferrite chokes next time as well - or maybe I can get the club to add some to the Field Day kit. Any thoughts from the gallery? 73 -Jim NU0C (BTW, the Echelon headset knocked the generator noise right out of the headphones...) -- Submissions:drakelist@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@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
Re: [drakelist] Antenna question
Buy or make 40 meter traps and use it on multiple bands. The traps will shorten the overall antenna length. 73, Gary
Re: [drakelist] Drake Twins On CW
Dan Ringer [EMAIL PROTECTED] made an utterance to the drakelist gang -- On 3 Jul 2008 at 15:24, EP Swynar wrote: What a wonderful pair of rigs for CW --- they really complement each other, and in more ways than one! I'd never had the T-4X even on before,until this past weekend (I acquired both rigs last December), and was quite impressed with it... I had no luck getting the rig to operate on 'phone, though...I guess I'll have to play around with the wires coming out the base of the amplified D-104 some more, before I try to get into the rig itself (I just HATE those amplified mics!). The PTT seems to work A-OK --- there's just no audio! Eddy, I suggest simply bypassing the amp on the D104. The T4Xany doesn't need it. I use an unamplified D104 and get great audio reports on my T4XB. Dan, K8WV --- Darrell (Dan) Ringer Attorney at Law ABA Solo Practitioner of the Year Past-President, WV State Bar WV Lawyer of the Year Fellow, WV Bar Foundation 823 Fairmont Road Morgantown, WV 26501 304-292-1999 FAX 304-292-3372 = Watch THE LAW WORKS (http://www.thelawworks.org) on WV Public Television, Thursdays at 8:30 p.m. = -- Submissions:drakelist@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] Pondering RF Feedback (TR7/SP75)
Mike Manship [EMAIL PROTECTED] made an utterance to the drakelist gang -- The .01uF added to the PS7 helped at low power but when I ran an amp I still had some RF in the audio unless I used a 12 volt DC wall wart power supply to power my SP75. I was able to use it on my Corsair that way as well as the TR7. 73 de Mike W9OJ [EMAIL PROTECTED] made an utterance to the drakelist gang -- I have also grounded my speech processors and other audio peripherals in this fashion. Additiionally, Drake published a bulletin regarding the bypassing of the PS7's AUX 12v output connector with a .01uF disk cap. (This was noted to be of concern when powering an SP75 from the PS7.) All of my PS7s have been thusly equipped...and have had no RF feedback problems since. 73 - Fred, N8YX -- Submissions:drakelist@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@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] Antenna question
For years I have used a trapped inverted Vee using Reyco 40M traps and a W2AU balun. Works great on 80M and 40M and will work other bands with a tuner. A good antenna. Also, no matter what they say, The G5RV at 102 feet long is a fine performer on 80, 40 and 20 for sure. Do not sell it short. I use one at 30' with a DX-60B and Drake R4A (mostly on 40 CW) and get consistently great reports. Rick W0RT - Original Message - From: Gary Poland To: drakelist@zerobeat.net Sent: Thursday, July 03, 2008 4:01 PM Subject: Re: [drakelist] Antenna question Buy or make 40 meter traps and use it on multiple bands. The traps will shorten the overall antenna length. 73, Gary
Re: [drakelist] Pondering RF Feedback (TR7/SP75)
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Thu, 03 Jul 2008 16:50:00 -0400, [EMAIL PROTECTED] wrote: Additiionally, Drake published a bulletin regarding the bypassing of the PS7's AUX 12v output connector with a .01uF disk cap. (This was noted to be of concern when powering an SP75 from the PS7.) Thanks, Fred. My PS is a 30 Amp Astron clone, of sorts. I had already checked it, and found it to be both bypassed and chassis grounded. I't been very reliable. 73 -Jim -- Submissions:drakelist@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] Pondering RF Feedback (TR7/SP75)
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Thu, 3 Jul 2008 22:56:52 +0200, Dieter Horst wrote: The slides can be found here: http://www.bavarian-contest-club.de/storage/med/papers/linden2008/79_Linden2008_dk3yd.pdf That link didn't work for me: Sehr geehrter Nuter, sehr geehrte Nutzerin, Die gewünschte Datei ist nicht direkt verfügbar, bitte rufen Sie den verweisenden Artikel auf unserem System auf, und klicken Sie dort auf den Verweislink. Direktverweise von anderen Systemen werden von unseren Servern blockiert. wir bitten um Ihr Verständnis, Ihre Online-Redaktion -- Submissions:drakelist@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] Drake Twins On CW
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Thu, 03 Jul 2008 17:45:00 -0400, Dan Ringer wrote: Eddy, I suggest simply bypassing the amp on the D104. The T4Xany doesn't need it. I use an unamplified D104 and get great audio reports on my T4XB. I agree completely. Take that horrid amp out and nail it to the wall, put a 470K resistor in series with the audio lead, and that D104 will sound wonderful. 73 -Jim NU0C -- Submissions:drakelist@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] Pondering RF Feedback (TR7/SP75)
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Thu, 03 Jul 2008 08:36:40 -0400, [EMAIL PROTECTED] wrote: When and where to ground is not as simple as it sounds at first thought.? Depending on circuit design, several grounding schemes for microphones might have to be tried to ensure proper shielding while at the same time not creating a ground loop.? Too, ferrite beads on each and every lead going to/from the rig might help. Ferrites are on the list for next year. The chasssis grounding idea seems sound, especially considering that I've seen three tech notes so far on it. Here's the third one: http://audiosystemsgroup.com/AESPaperNYPin1-ASGWeb.pdf Thanks, Evan! 73 -Jim NU0C -- Submissions:drakelist@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] Drake Twins On CW
In a message dated 7/3/2008 7:33:43 PM Eastern Daylight Time, [EMAIL PROTECTED] writes: ron [EMAIL PROTECTED] made an utterance to the drakelist gang -- Dan Ringer wrote: Eddy, I suggest simply bypassing the amp on the D104. The T4Xany doesn't need it. I use an unamplified D104 and get great audio reports on my T4XB. Besides, them amplified D104's were made with CB'ers in mind at the time. Ham radio rigs, they are not needed. Ron wb1hga Well Maybe but I bought the Preamp from Astatic that went into the base of a G stand(D-104 is head alone), had to drill a few holes, one for access to the gain pot another on top for on/off switch, best $7.00 I ever spent. My New twins(1977) seemed to need more audio for some reason. Now I could talk a bit lower to accomplish the same. Too high a setting causes more background noise, not good, hi! If you got an amplified base, give it a try! GL es 73.. Rich WA2RQY/4
Re: [drakelist] Drake Twins On CW
Jim Shorney [EMAIL PROTECTED] made an utterance to the drakelist gang -- On Thu, 3 Jul 2008 21:13:13 EDT, [EMAIL PROTECTED] wrote: Well Maybe but I bought the Preamp from Astatic Heck, I would have given you one if you really wanted it... :) My New twins(1977) seemed to need more audio for some reason. I haven't tried a D104 on the twins yet, but every other rig I've tried one on has not needed the amp. Currently I'm using a Golden Eagle version on the TR7, sans preamp. plus 470K resistor. Plenty of audio. I'll probably move the Golden Eagle over to the HyGain 3750, as it's a better style match. Keeping my eyes open for a Silver Eagle for the TR7. Still using Shure 444s on the C-Line and TR6. Although I've got an EV RE-20 I'm gonna hook up to something... Since I've got plenty of standard T-UG8/D104 around here, I'll probably try one on the twins someday. Without the amp, of couse. 73 -Jim NU0C -- Submissions:drakelist@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 --
