Re: [Elecraft] CP1 Power Handling
Hi I have both the 20 db and 30 db versions of the CP1. Even though the 20 db is not rated that high I have used it at 100 watts with no problems for short times. I use them with the OHR WM-2 wattmeter. To get it to go to 200 watts you would at least need to increase the wattage of the terminating resistors on the CP1 and probably need to increase the core size on the toroids. Of course I have not done this so I am just guessing. Don Brown KD5NDB - Original Message - From: Linden, Mike (BRC-Hes) [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Tuesday, March 07, 2006 8:33 AM Subject: [Elecraft] CP1 Power Handling Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
You have a couple options. The flux density is higher, and therefore heating, with lower number of turns. They also go to a -43 mix (higher permeability) for the lower turns to keep the shunt reactance of the voltage xfmr high at 1.8 MHz. If you don't care about 1.8 MHz, you might be able to get by with 10 turns on the -61 cores... I would have to do the math. The other option is to stick with the -43 material, but get larger cores. I'm pretty sure they make the FT50A and FT50B (which are thicker) in -43 material, or you could go to a FT68 or FT82 if they'll fit. The best bet would probably be FT50A-43, since we know it would fit physically. I have a spreadsheet that I use that calculates these things for me... I can plug these in to see what would work if you like. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] CP1 Power Handling
Larry, If you have the time, I'd certainly appreciate it if you'd run it through your spreadsheet for me. Thanks! -Michael == You have a couple options. The flux density is higher, and therefore heating, with lower number of turns. They also go to a -43 mix (higher permeability) for the lower turns to keep the shunt reactance of the voltage xfmr high at 1.8 MHz. If you don't care about 1.8 MHz, you might be able to get by with 10 turns on the -61 cores... I would have to do the math. The other option is to stick with the -43 material, but get larger cores. I'm pretty sure they make the FT50A and FT50B (which are thicker) in -43 material, or you could go to a FT68 or FT82 if they'll fit. The best bet would probably be FT50A-43, since we know it would fit physically. I have a spreadsheet that I use that calculates these things for me... I can plug these in to see what would work if you like. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
A quick check shows that no small size cores will work for -43 material with 10T at 1.8 MHz and 200W. However, FT50B cores come close, and are fine at 3.5 MHz. FT50B is twice the thickness of the FT50A, and would fit on the board because the thickness would only add height. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Larry, If you have the time, I'd certainly appreciate it if you'd run it through your spreadsheet for me. Thanks! -Michael == You have a couple options. The flux density is higher, and therefore heating, with lower number of turns. They also go to a -43 mix (higher permeability) for the lower turns to keep the shunt reactance of the voltage xfmr high at 1.8 MHz. If you don't care about 1.8 MHz, you might be able to get by with 10 turns on the -61 cores... I would have to do the math. The other option is to stick with the -43 material, but get larger cores. I'm pretty sure they make the FT50A and FT50B (which are thicker) in -43 material, or you could go to a FT68 or FT82 if they'll fit. The best bet would probably be FT50A-43, since we know it would fit physically. I have a spreadsheet that I use that calculates these things for me... I can plug these in to see what would work if you like. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] CP1 Power Handling
Larry, Thanks! 200W is probably a bit on the high side for my needs (safety margin), so this looks pretty good. -Michael -Original Message- From: Larry Phipps [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 07, 2006 10:29 AM To: Linden, Mike (BRC-Hes) Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] CP1 Power Handling A quick check shows that no small size cores will work for -43 material with 10T at 1.8 MHz and 200W. However, FT50B cores come close, and are fine at 3.5 MHz. FT50B is twice the thickness of the FT50A, and would fit on the board because the thickness would only add height. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Larry, If you have the time, I'd certainly appreciate it if you'd run it through your spreadsheet for me. Thanks! -Michael ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
Hi Michael, I designed the CP1 for Elecraft and in the process I performed many tests to evaluate the power handling capabilities. The power is limited by heating of the core and that is primarily a function of flux density and time. The published specification allows the rated power to be applied for long periods of time without excessive heating. The flux density is proportional to the applied voltage, i.e. square root of power, and inversely proportional to the number of turns, cross sectional area, and frequency. For a 20 dB coupler the number of turns is fixed at 10. Because of the small turns count type 43 material was chosen to provide sufficient inductance to maintain performance at the lowest frequency. Unfortunately, type 43 has a relatively low Curie Temperature, that is, the temperature at which the magnetic properties of the core disappear. Other core materials have much higher temperature ratings and lower loss, but they do not provide sufficient inductance for good performance on 160 meters. So what does all this mean? I suggest that the easiest thing for you to do would be to stack three cores together at each position. It will be easier to wind the cores if you use some sort of adhesive to hold the cores together. This will provide about 9 times the power handling capability and meet your power requirement. If you don't hold the key down for 5 minutes even better. You can order the extra cores from Elecraft. 73, Bob, N6CM - Original Message - From: Linden, Mike (BRC-Hes) [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Tuesday, March 07, 2006 6:33 AM Subject: [Elecraft] CP1 Power Handling Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
It might also make sense to increase the turns to 14, which would give a coupling factor of 23 dB, and much more safety margin. Larry N8LP Linden, Mike (BRC-Hes) wrote: Larry, Thanks! 200W is probably a bit on the high side for my needs (safety margin), so this looks pretty good. -Michael -Original Message- From: Larry Phipps [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 07, 2006 10:29 AM To: Linden, Mike (BRC-Hes) Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] CP1 Power Handling A quick check shows that no small size cores will work for -43 material with 10T at 1.8 MHz and 200W. However, FT50B cores come close, and are fine at 3.5 MHz. FT50B is twice the thickness of the FT50A, and would fit on the board because the thickness would only add height. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Larry, If you have the time, I'd certainly appreciate it if you'd run it through your spreadsheet for me. Thanks! -Michael ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
Stacking cores can also help increase power handling capability without taking more pcb space (providing the core is flat on the pcb). -- Alan wb6zqz -- Original message -- From: Larry Phipps [EMAIL PROTECTED] A quick check shows that no small size cores will work for -43 material with 10T at 1.8 MHz and 200W. However, FT50B cores come close, and are fine at 3.5 MHz. FT50B is twice the thickness of the FT50A, and would fit on the board because the thickness would only add height. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Larry, If you have the time, I'd certainly appreciate it if you'd run it through your spreadsheet for me. Thanks! -Michael == You have a couple options. The flux density is higher, and therefore heating, with lower number of turns. They also go to a -43 mix (higher permeability) for the lower turns to keep the shunt reactance of the voltage xfmr high at 1.8 MHz. If you don't care about 1.8 MHz, you might be able to get by with 10 turns on the -61 cores... I would have to do the math. The other option is to stick with the -43 material, but get larger cores. I'm pretty sure they make the FT50A and FT50B (which are thicker) in -43 material, or you could go to a FT68 or FT82 if they'll fit. The best bet would probably be FT50A-43, since we know it would fit physically. I have a spreadsheet that I use that calculates these things for me... I can plug these in to see what would work if you like. 73, Larry N8LP Linden, Mike (BRC-Hes) wrote: Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
Bob, have you seen any difference between stacked cores and solid ones of the same total thickness? In designed my wattmeters, I found more heating with stacked cores... at least for one combination. The FT50B core is the same thickness as 2.66 stacked FT50 cores, or 2 FT50A cores. Larry N8LP Robert Friess wrote: Hi Michael, I designed the CP1 for Elecraft and in the process I performed many tests to evaluate the power handling capabilities. The power is limited by heating of the core and that is primarily a function of flux density and time. The published specification allows the rated power to be applied for long periods of time without excessive heating. The flux density is proportional to the applied voltage, i.e. square root of power, and inversely proportional to the number of turns, cross sectional area, and frequency. For a 20 dB coupler the number of turns is fixed at 10. Because of the small turns count type 43 material was chosen to provide sufficient inductance to maintain performance at the lowest frequency. Unfortunately, type 43 has a relatively low Curie Temperature, that is, the temperature at which the magnetic properties of the core disappear. Other core materials have much higher temperature ratings and lower loss, but they do not provide sufficient inductance for good performance on 160 meters. So what does all this mean? I suggest that the easiest thing for you to do would be to stack three cores together at each position. It will be easier to wind the cores if you use some sort of adhesive to hold the cores together. This will provide about 9 times the power handling capability and meet your power requirement. If you don't hold the key down for 5 minutes even better. You can order the extra cores from Elecraft. 73, Bob, N6CM - Original Message - From: Linden, Mike (BRC-Hes) [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Tuesday, March 07, 2006 6:33 AM Subject: [Elecraft] CP1 Power Handling Does anyone know what modifications would need to be made to the CP1 Directional Coupler in order to get it to handle 200W at 20dB attenuation? I'd like to use the CP1 as a cost effective means of extending the useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more attenuation than I want and the power handling at 20dB is not high enough. Thanks, Michael N9BDF ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
Bob What combination of core/turns would give up to 40dB and able to handle 100 watts and what frequency range would it have? Main interest is HF 73 Jim VE3TTN On Mar 7, 2006, at 11:46, Robert Friess wrote: Hi Michael, I designed the CP1 for Elecraft and in the process I performed many tests to evaluate the power handling capabilities. The power is limited by heating of the core and that is primarily a function of flux density and time. The published specification allows the rated power to be applied for long periods of time without excessive heating. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] CP1 Power Handling
Robert, Thanks for the insight and alternate solution! -Michael -Original Message- From: Robert Friess [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 07, 2006 10:46 AM To: Linden, Mike (BRC-Hes); elecraft@mailman.qth.net Subject: Re: [Elecraft] CP1 Power Handling Hi Michael, I designed the CP1 for Elecraft and in the process I performed many tests to evaluate the power handling capabilities. The power is limited by heating of the core and that is primarily a function of flux density and time. The published specification allows the rated power to be applied for long periods of time without excessive heating. The flux density is proportional to the applied voltage, i.e. square root of power, and inversely proportional to the number of turns, cross sectional area, and frequency. For a 20 dB coupler the number of turns is fixed at 10. Because of the small turns count type 43 material was chosen to provide sufficient inductance to maintain performance at the lowest frequency. Unfortunately, type 43 has a relatively low Curie Temperature, that is, the temperature at which the magnetic properties of the core disappear. Other core materials have much higher temperature ratings and lower loss, but they do not provide sufficient inductance for good performance on 160 meters. So what does all this mean? I suggest that the easiest thing for you to do would be to stack three cores together at each position. It will be easier to wind the cores if you use some sort of adhesive to hold the cores together. This will provide about 9 times the power handling capability and meet your power requirement. If you don't hold the key down for 5 minutes even better. You can order the extra cores from Elecraft. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] CP1 Power Handling
That would not be very practical, because it would be 100 turns. I suggest using the existing 30dB design, and add external inline BNC attenuators like the Mini-Circuits HAT-10. That would give you 40 dB total. Larry N8LP Jim Byers wrote: Bob What combination of core/turns would give up to 40dB and able to handle 100 watts and what frequency range would it have? Main interest is HF 73 Jim VE3TTN On Mar 7, 2006, at 11:46, Robert Friess wrote: Hi Michael, I designed the CP1 for Elecraft and in the process I performed many tests to evaluate the power handling capabilities. The power is limited by heating of the core and that is primarily a function of flux density and time. The published specification allows the rated power to be applied for long periods of time without excessive heating. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
