Re: Topband: Two 2:1 transformers to choose from!!
That's great, Jim!! Sounds like it's working well!! Have fun! I'm sure you will like it! 73, Charlie, K4OTV From: James Rodenkirch [mailto:rodenkirch_...@msn.com] Sent: Sunday, August 25, 2013 9:53 AM To: Charlie Cunningham Subject: RE: Topband: Two 2:1 transformers to choose from!! Got the delta loop up and wired over the past three days, Charlie!! Tried it out last night and, before the preamp died, I was seeing an S unit to two difference when switch between east and west direction on 80 meters and 40. The preamp died as I was getting on 160 BUT...I did use the preamp in my Argonaut VI, just to see how it worked and, while listening to some SSB stations I did a switcheroo (have a switch in the DC voltage line to the relays out at the antenna) and saw a solid 2 S unit difference on at least two of the stations. Comparing the noise level of my vertical versus the delta loop shows the noise level is reduced by at least 3 to 4 S units. So, something is working Hi Hi Conditions on 160 weren't great this morning AND the entire lash up at my operating table was very kluged - going to make up a DC power distribution box and add the switches (switch the relays in or out to switch direction from east to west or vice versa)o be and a T/R relay circuit (as soon as I find one and get the pars) so more 'work' and planning to be done. I have only had it up and running since yesterday afternoon so lots of testing still in order. I don't have any test equipment other than a DVM and a noise bridge but will be fun to play with it when signals are being heard. 72, Jim Rodenkirch K9JWV From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; mikew...@gmail.com; topband@contesting.com Date: Thu, 22 Aug 2013 15:18:40 -0400 Subject: Re: Topband: Two 2:1 transformers to choose from!! That's great, Jim! Let me know how it plays! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Thursday, August 22, 2013 3:00 PM To: Charlie Cunningham; 'Mike Waters'; 'topband' Subject: Re: Topband: Two 2:1 transformers to choose from!! When time permits, Charlie, I will do just that! Almost done with everything up to the two boxes with the switchable components - resistor, xfmr - as I await the xfmr(s) arrival. Outta be listening by Sunday morning!! From: charlie-cunning...@nc.rr.com To: rodenkirch_...@msn.com; mikew...@gmail.com; topband@contesting.com Subject: RE: Topband: Two 2:1 transformers to choose from!! Date: Thu, 22 Aug 2013 14:41:40 -0400 Well, Jim Since you wound both transformers, why not try them both, and see if you can measure any difference? I' guessing you won't see much! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Thursday, August 22, 2013 2:00 PM To: Mike Waters; topband Subject: Re: Topband: Two 2:1 transformers to choose from!! Thanks, Mike - will try the 2:3 ratio one first! Date: Thu, 22 Aug 2013 10:21:14 -0500 From: mikew...@gmail.com To: rodenkirch_...@msn.com; topband@contesting.com Subject: Re: Topband: Two 2:1 transformers to choose from!! P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on the low-Z primary for binocular cores. It might work, but there are other turns ratios you might try. Here is a list of turns ratios for those cores I made: http://www.w0btu.com/Binocular_core_turns_ratios.pdf If you get a 500 Server Error message, contact me directly and I'll e-mail it to you. 73, Mike www.w0btu.com On Wed, Aug 21, 2013 at 3:49 PM, James Rodenkirch rodenkirch_...@msn.comwrote: I received enuff info and thoughts to know I'll utilize the 5:7 winding version. _ Topband Reflector _ Topband Reflector _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Ever since I added back-to-back 1N4148's between the preamp's input and ground many years ago, I have never lost a transistor in my preamp. Before that, it seemed that I was replacing it after nearly every thunderstorm. A couple of years ago I changed it a little: I added a small incandescent lamp in series with the preamp input. At the same I changed from just two to four of the same diodes in series/parallel. There are other ways as good or better than this, but this works for me. 73, Mike www.w0btu.com On Sun, Aug 25, 2013 at 10:13 AM, James Rodenkirch rodenkirch_...@msn.comwrote: Any ideas on a front end protection circuit for a preampl? _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
That's always worked for me, Mike! The bit of resistance that I suggested that Jim add ahead of the FET gate and the diodes serves the same purpose as your incandescent lamp - but I expect that the lamp is more rugged and forgiving. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Sunday, August 25, 2013 4:15 PM To: James Rodenkirch; topband Subject: Re: Topband: Two 2:1 transformers to choose from!! Ever since I added back-to-back 1N4148's between the preamp's input and ground many years ago, I have never lost a transistor in my preamp. Before that, it seemed that I was replacing it after nearly every thunderstorm. A couple of years ago I changed it a little: I added a small incandescent lamp in series with the preamp input. At the same I changed from just two to four of the same diodes in series/parallel. There are other ways as good or better than this, but this works for me. 73, Mike www.w0btu.com On Sun, Aug 25, 2013 at 10:13 AM, James Rodenkirch rodenkirch_...@msn.comwrote: Any ideas on a front end protection circuit for a preampl? _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Got it, Mike and Charlie - will do something like that - reverse diodes across the input, if nuthin' else! From: charlie-cunning...@nc.rr.com To: mikew...@gmail.com; rodenkirch_...@msn.com; topband@contesting.com Date: Sun, 25 Aug 2013 16:21:05 -0400 Subject: Re: Topband: Two 2:1 transformers to choose from!! That's always worked for me, Mike! The bit of resistance that I suggested that Jim add ahead of the FET gate and the diodes serves the same purpose as your incandescent lamp - but I expect that the lamp is more rugged and forgiving. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Sunday, August 25, 2013 4:15 PM To: James Rodenkirch; topband Subject: Re: Topband: Two 2:1 transformers to choose from!! Ever since I added back-to-back 1N4148's between the preamp's input and ground many years ago, I have never lost a transistor in my preamp. Before that, it seemed that I was replacing it after nearly every thunderstorm. A couple of years ago I changed it a little: I added a small incandescent lamp in series with the preamp input. At the same I changed from just two to four of the same diodes in series/parallel. There are other ways as good or better than this, but this works for me. 73, Mike www.w0btu.com On Sun, Aug 25, 2013 at 10:13 AM, James Rodenkirch rodenkirch_...@msn.comwrote: Any ideas on a front end protection circuit for a preampl? _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
So the general concessions is that 7:5 turns was better. Do is 15:7 turns or 21:10 turns better? Whats best for 160M ? -- Jim K9TF _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
All those turns are better for what? For the winding that's connected to the coax (either 50 or 75 ohms), two turns is plenty. And good luck stuffing all that wire inside the holes in those binocular cores, especially if you use the recommended protective insulating liner. :-) 73, Mike www.w0btu.com On Sat, Aug 24, 2013 at 4:27 PM, Jim GM jim.gmfo...@gmail.com wrote: So the general concessions is that 7:5 turns was better. Do is 15:7 turns or 21:10 turns better? Whats best for 160M ? _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
As I recall, when I wound the tranformer for my 40' X 10' KAZ terminated loop, I wound it 3:13 T because I was trying to match from 50 ohms up to around 950 ohms. The core I used was binocular that I cobbled together by taping together two Fair-Rite tubular cores, side-by-side. I used wire-wrap wire. Worked really well, and surely helped me on 160 and 80m, but it was a great receive antenna for 40 and 30m as well. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Saturday, August 24, 2013 6:00 PM To: topband Subject: Re: Topband: Two 2:1 transformers to choose from!! All those turns are better for what? For the winding that's connected to the coax (either 50 or 75 ohms), two turns is plenty. And good luck stuffing all that wire inside the holes in those binocular cores, especially if you use the recommended protective insulating liner. :-) 73, Mike www.w0btu.com On Sat, Aug 24, 2013 at 4:27 PM, Jim GM jim.gmfo...@gmail.com wrote: So the general concessions is that 7:5 turns was better. Do is 15:7 turns or 21:10 turns better? Whats best for 160M ? _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
I'm not sure what kind of material you made that from, but 3 or even 4 turns is OK for the low-Z winding on the #73 solid 2-hole cores we were talking about earlier. It seemed to work well for you. :-) Sometimes, we have to cascade two transformers to get to the Z ratio we want. 73, Mike www.w0btu.com On Sat, Aug 24, 2013 at 6:38 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: As I recall, when I wound the tranformer for my 40' X 10' KAZ terminated loop, I wound it 3:13 T because I was trying to match from 50 ohms up to around 950 ohms. The core I used was binocular that I cobbled together by taping together two Fair-Rite tubular cores, side-by-side. I used wire-wrap wire. Worked really well, and surely helped me on 160 and 80m, but it was a great receive antenna for 40 and 30m as well. _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Pretty sure it's 73 material, Mike. That's about all I had in my Fair-Rite engineering and designer kits. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Saturday, August 24, 2013 8:12 PM To: Charlie Cunningham Cc: topband Subject: Re: Topband: Two 2:1 transformers to choose from!! I'm not sure what kind of material you made that from, but 3 or even 4 turns is OK for the low-Z winding on the #73 solid 2-hole cores we were talking about earlier. It seemed to work well for you. :-) Sometimes, we have to cascade two transformers to get to the Z ratio we want. 73, Mike www.w0btu.com On Sat, Aug 24, 2013 at 6:38 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: As I recall, when I wound the tranformer for my 40' X 10' KAZ terminated loop, I wound it 3:13 T because I was trying to match from 50 ohms up to around 950 ohms. The core I used was binocular that I cobbled together by taping together two Fair-Rite tubular cores, side-by-side. I used wire-wrap wire. Worked really well, and surely helped me on 160 and 80m, but it was a great receive antenna for 40 and 30m as well. _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on the low-Z primary for binocular cores. It might work, but there are other turns ratios you might try. Here is a list of turns ratios for those cores I made: http://www.w0btu.com/Binocular_core_turns_ratios.pdf If you get a 500 Server Error message, contact me directly and I'll e-mail it to you. 73, Mike www.w0btu.com On Wed, Aug 21, 2013 at 3:49 PM, James Rodenkirch rodenkirch_...@msn.comwrote: I received enuff info and thoughts to know I'll utilize the 5:7 winding version. _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Thanks, Mike - will try the 2:3 ratio one first! Date: Thu, 22 Aug 2013 10:21:14 -0500 From: mikew...@gmail.com To: rodenkirch_...@msn.com; topband@contesting.com Subject: Re: Topband: Two 2:1 transformers to choose from!! P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on the low-Z primary for binocular cores. It might work, but there are other turns ratios you might try. Here is a list of turns ratios for those cores I made: http://www.w0btu.com/Binocular_core_turns_ratios.pdf If you get a 500 Server Error message, contact me directly and I'll e-mail it to you. 73, Mike www.w0btu.com On Wed, Aug 21, 2013 at 3:49 PM, James Rodenkirch rodenkirch_...@msn.comwrote: I received enuff info and thoughts to know I'll utilize the 5:7 winding version. _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Well, Jim Since you wound both transformers, why not try them both, and see if you can measure any difference? I' guessing you won't see much! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Rodenkirch Sent: Thursday, August 22, 2013 2:00 PM To: Mike Waters; topband Subject: Re: Topband: Two 2:1 transformers to choose from!! Thanks, Mike - will try the 2:3 ratio one first! Date: Thu, 22 Aug 2013 10:21:14 -0500 From: mikew...@gmail.com To: rodenkirch_...@msn.com; topband@contesting.com Subject: Re: Topband: Two 2:1 transformers to choose from!! P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on the low-Z primary for binocular cores. It might work, but there are other turns ratios you might try. Here is a list of turns ratios for those cores I made: http://www.w0btu.com/Binocular_core_turns_ratios.pdf If you get a 500 Server Error message, contact me directly and I'll e-mail it to you. 73, Mike www.w0btu.com On Wed, Aug 21, 2013 at 3:49 PM, James Rodenkirch rodenkirch_...@msn.comwrote: I received enuff info and thoughts to know I'll utilize the 5:7 winding version. _ Topband Reflector _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
It pretty much boils down to what frequencies you want to cover. To cover down to the 600M band and below use more turns and to go up to 30 or 20M the 2-3T at 50-75 Ohms does well. I use a VNA and 73-202 transformers to tweak what I want and the effect of interwinding capacitance can also be seen. Im also installing a few new reversibles for LF using more turns. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: James Rodenkirch rodenkirch_...@msn.com; topband topband@contesting.com Sent: Thursday, August 22, 2013 11:21 AM Subject: Re: Topband: Two 2:1 transformers to choose from!! P. 7-69 of Low Band Dxing (5th ed.) by ON4UN says a maximum of 4 turns on the low-Z primary for binocular cores. It might work, but there are other turns ratios you might try. Here is a list of turns ratios for those cores I made: http://www.w0btu.com/Binocular_core_turns_ratios.pdf If you get a 500 Server Error message, contact me directly and I'll e-mail it to you. 73, Mike www.w0btu.com On Wed, Aug 21, 2013 at 3:49 PM, James Rodenkirch rodenkirch_...@msn.comwrote: I received enuff info and thoughts to know I'll utilize the 5:7 winding version. _ Topband Reflector - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1432 / Virus Database: 3211/6097 - Release Date: 08/21/13 _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Since you wound both transformers, why not try them both, and see if you can measure any difference? I' guessing you won't see much! Unless the antenna system is starved for background noise, or the element is in an end-fire phased array, it makes very little difference. The only real effect of mismatch is signal and noise from the antenna drop equally. Outside of a low sensitivity array, or an array that is phased end-fire, until background drops with 10 dB of RX system noise floor, or preamp noise floor, it really doesn't matter. Two turns for 75 ohms is plenty for decent 100 kHz to 30 MHz performance. Now if you hook up a Sky Buddy, it's a different problem. :) Tom _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
That is EXACTLY what I have experienced here. 73, Mike www.w0btu.com On Thu, Aug 22, 2013 at 8:40 PM, Tom W8JI w...@w8ji.com wrote: Two turns for 75 ohms is plenty for decent 100 kHz to 30 MHz performance. _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
I meant to add unless you need a certain impedance ratio. On Thu, Aug 22, 2013 at 8:51 PM, Mike Waters mikew...@gmail.com wrote: That is EXACTLY what I have experienced here. 73, Mike www.w0btu.com On Thu, Aug 22, 2013 at 8:40 PM, Tom W8JI w...@w8ji.com wrote: Two turns for 75 ohms is plenty for decent 100 kHz to 30 MHz performance. _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
Well, that FO0AAA KAZ terminated loop has pretty good gain as terminated RX loops go, so I wouldn't expect the system to be noise starved, but the gain opf that loop is of the order of -30 dBi at 160, so a preamp is in order. Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Thursday, August 22, 2013 9:41 PM To: 'topband' Subject: Re: Topband: Two 2:1 transformers to choose from!! Since you wound both transformers, why not try them both, and see if you can measure any difference? I' guessing you won't see much! Unless the antenna system is starved for background noise, or the element is in an end-fire phased array, it makes very little difference. The only real effect of mismatch is signal and noise from the antenna drop equally. Outside of a low sensitivity array, or an array that is phased end-fire, until background drops with 10 dB of RX system noise floor, or preamp noise floor, it really doesn't matter. Two turns for 75 ohms is plenty for decent 100 kHz to 30 MHz performance. Now if you hook up a Sky Buddy, it's a different problem. :) Tom _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
I'd be surprised if a little mismatch between an approx. 100 ohm twisted pair and 50 ohm coax would make any really noticeable difference, but some sort of balun might be in order. For the 40' X 10' KAZ loop that I had, I just tied the primary of the transformer to some RG-58 that ran through an old tunable AMECO tube preamp to the RX antenna input of the FT-1000MP. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Thursday, August 22, 2013 9:58 PM To: topband Subject: Re: Topband: Two 2:1 transformers to choose from!! I meant to add unless you need a certain impedance ratio. On Thu, Aug 22, 2013 at 8:51 PM, Mike Waters mikew...@gmail.com wrote: That is EXACTLY what I have experienced here. 73, Mike www.w0btu.com On Thu, Aug 22, 2013 at 8:40 PM, Tom W8JI w...@w8ji.com wrote: Two turns for 75 ohms is plenty for decent 100 kHz to 30 MHz performance. _ Topband Reflector _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
I'm sure that's a good one, Mike. When I built my RX loop, I was busy and In a hurry, and I borrowed one of the old original AMECO tube preamps from my friend, Bill, K4CIA. Worked great on 160,80, 40 and 30m with the terminated loop. The AMECO preamp was tunable, rather than broad band. 73, Charlie, K4OTV From: Mike Waters [mailto:mikew...@gmail.com] Sent: Thursday, August 22, 2013 10:41 PM To: Charlie Cunningham; topband Subject: Re: Topband: Two 2:1 transformers to choose from!! This is the preamp I use. The circuit is from Solid State Design For the Radio Amateur, C 1977 ARRL. W8JI suggested it to me over 30 years ago (but I think he has much better preamp designs since then). http://www.w0btu.com/W0BTU-broadband-preamps.html W7IUV enhanced it. 73, Mike www.w0btu.com On Thu, Aug 22, 2013 at 9:25 PM, Charlie Cunningham charlie-cunning...@nc.rr.com wrote: Well, that FO0AAA KAZ terminated loop has pretty good gain as terminated RX loops go, so I wouldn't expect the system to be noise starved, but the gain opf that loop is of the order of -30 dBi at 160, so a preamp is in order. _ Topband Reflector
Re: Topband: Two 2:1 transformers to choose from!!
I received enuff info and thoughts to know I'll utilize the 5:7 winding version. Thanks to all that replied! 72, Jim Rodenkirch K9JWV From: rodenkirch_...@msn.com To: topband@contesting.com Subject: Two 2:1 transformers to choose from!! Date: Wed, 21 Aug 2013 13:23:37 -0600 I have two impedance transformers wound on BN 73-202 cores that I can use for the 2:1 impedance transformer I need for my FO0AAA delta receiving antenna. One has a 2 turn and 3 turn winding- giving a 4:9 impedance ratio. The other has a 7 turn and 5 turn winding, giving a 25:49 impedance ratio. I don't know which would be better - I believe the one with more turns probably has better coupling, but more loss?!?! I am splitting fine hairs here butI am curious if one might say, 'Use x instead of y, JimThoughts??? 72, Jim Rodenkirch K9JWV _ Topband Reflector
