Re: Topband: KD9SV-OK1RR relays ???
It seems to me that a very fast operating preamp protection circuit could be constructed employing a good fast saturating NPN switching transistor across the antenna path. In receive mode the collector-base junction would have substantial reverse bias and the transistor can be chosen for low collector-base capacitance. With a fast switch like a 2N708 or something similar the switching time will, of course, FAR outperform a relay closure time. This thread might have splintered. I was responding to this:
Re: Topband: KD9SV-OK1RR relays ???
Hello all It seems to me that a very fast operating preamp protection circuit could be constructed employing a good fast saturating NPN switching transistor across the antenna path. In receive mode the collector-base junction would have substantial reverse bias and the transistor can be chosen for low collector-base capacitance. With a fast switch like a 2N708 or something similar the switching time will, of course, FAR outperform a relay closure time. One can also add a few ohms in series with the antenna lead to reduce the requirements for collector current in the saturating switch. That approach should help with the switching speed and contact bounce issues. However, if the radio design is poor and there are T/R sequencing issues - those will require additional means to correct or deal with the improper T/R sequencing problems. The turnoff time for the saturating switch, even at low forced gains should be fast enough to cope with very fast keying speeds. Just a thought. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Saturday, August 29, 2015 6:14 PM To: topBand List Subject: Re: Topband: KD9SV-OK1RR relays ??? > Your FT-747 only has one antenna input. It does not have a second > receiver. It doesn't even have a receive-only antenna input. You cannot > transmit and receive at same time. Why do you need a "front end saver"? It needs a preamp saver or a receiver antenna saver, not a front end saver. "Any old relay" will not work. Here is what the sequence is: 1.) The radio antenna port is connected through a small relay to the receive preamp output, or to the receive antenna 2.) The key is closed 3.) At time X, after the key is closed, something tells the receiver relay to release 4.) At the same time as the key is pressed, something tells the transmitter to transmit. Let's call this delay time Y. Now this is where the problem is. Many radios, especially the less expensive radios with a single antenna, have a Y time as short as X time. Some have X a little longer than Y, some have Y a little longer than X. There is no guarantee without looking at the radio on ALL modes if X time is shorter than X. Almost all radios are not 10mS, the relay time you suggested as a limit. Almost all radios are shorter than that, and some actually transmit while the external relay line is held low. There is an additional problem in a few radios. There are a few radios that tell the relay control line to release while they are still transmitting. At the end of a transmission, when you stop transmitting, a few radios will actually turn the external circuits off **before** they stop putting out RF power. I actually had to add a RF interlock in T-R relays for amplifiers just for those radios. Any relay used for this application should be as fast as possible. It should NOT have a diode across the coil, because that slows the release time down considerably. I would say the safe minimum speed for most radios would be about a 5 mS relay transfer, including bounce. A few radios will be worse than that, and have almost no delay. They would require a very fast relay, or a sequencing system. Some radios are designed so poorly they tell the external things to transfer while RF is present. Those radios cannot be fixed without external interlock systems. By the way, if this does not damage the RX system, it will cause contact spark clicks. It will also fold some radios back into SWR protect because the relay transfers with TX RF applied. The crummy interface timing in radios has been a nightmare ever since the first transceiver came out, and continues to be a problem today. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: KD9SV-OK1RR relays ???
Your FT-747 only has one antenna input. It does not have a second receiver. It doesn't even have a receive-only antenna input. You cannot transmit and receive at same time. Why do you need a "front end saver"? It needs a preamp saver or a receiver antenna saver, not a front end saver. "Any old relay" will not work. Here is what the sequence is: 1.) The radio antenna port is connected through a small relay to the receive preamp output, or to the receive antenna 2.) The key is closed 3.) At time X, after the key is closed, something tells the receiver relay to release 4.) At the same time as the key is pressed, something tells the transmitter to transmit. Let's call this delay time Y. Now this is where the problem is. Many radios, especially the less expensive radios with a single antenna, have a Y time as short as X time. Some have X a little longer than Y, some have Y a little longer than X. There is no guarantee without looking at the radio on ALL modes if X time is shorter than X. Almost all radios are not 10mS, the relay time you suggested as a limit. Almost all radios are shorter than that, and some actually transmit while the external relay line is held low. There is an additional problem in a few radios. There are a few radios that tell the relay control line to release while they are still transmitting. At the end of a transmission, when you stop transmitting, a few radios will actually turn the external circuits off **before** they stop putting out RF power. I actually had to add a RF interlock in T-R relays for amplifiers just for those radios. Any relay used for this application should be as fast as possible. It should NOT have a diode across the coil, because that slows the release time down considerably. I would say the safe minimum speed for most radios would be about a 5 mS relay transfer, including bounce. A few radios will be worse than that, and have almost no delay. They would require a very fast relay, or a sequencing system. Some radios are designed so poorly they tell the external things to transfer while RF is present. Those radios cannot be fixed without external interlock systems. By the way, if this does not damage the RX system, it will cause contact spark clicks. It will also fold some radios back into SWR protect because the relay transfers with TX RF applied. The crummy interface timing in radios has been a nightmare ever since the first transceiver came out, and continues to be a problem today. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: rx preamps
Yes, it is the latest version AFAIK. BTW the PCB is in process, it should be double sided, ready for production at Seeed Studio or other professional PCB maker. It is not needed for a single unit, WD8DSB has a good design well suited for home production. If there interests enough, I finalize my design and order the boards. Contact me on my private email: mar...@ok1rr.com or mar...@centrum.cz 73, Martin, OK1RR Dne 29.8.2015 v 21:26 Jim napsal(a): Martin is the latest incarnation of the infamous W7IUV preamp? and do you know anyone that has PC boards before I reinvent the wheel and make another one? Jim WA3MEJ - Original Message - Message: 10 Date: Fri, 28 Aug 2015 23:53:10 +0200 From: Martin Kratoska < mar...@centrum.cz > To: topband@contesting.com Subject: Topband: W7IUV preamp Message-ID: < 55e0d846.3070...@centrum.cz > Content-Type: text/plain; charset=windows-1252; format=flowed The latest version 6 http://www.okdxf.eu/files/preamp_r60.pdf 73, Martin, OK1RR _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: KD9SV-OK1RR relays ???
Tim, Yes, you are absolutely right Thanks, 73Douglas, CO8DM "No creo que haya alguna emoción más intensa para un inventor que ver alguna de sus creaciones funcionando. Esa emoción hace que uno se olvide de comer, de dormir, de todo." - Nikola Tesla - Original Message - From: "Tim Shoppa" Cc: "topBand List" Sent: Saturday, August 29, 2015 3:05 PM Subject: Re: Topband: KD9SV-OK1RR relays ??? Doug - Your FT-747 only has one antenna input. It does not have a second receiver. It doesn't even have a receive-only antenna input. You cannot transmit and receive at same time. Why do you need a "front end saver"? If you are adding an outboard relay keyed from the amp control line of the FT-747 to allow you to have separate transmit and receive antennas, that's great. Any old relay with less than 10ms make/break time will work fine there. You still don't need a "front end saver", because your rig still cannot be hooked to both transmit and receive antenna at same time. Tim N3QE _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: rx preamps
Hi Jim, You might want to check out my website that shows my builds of the W7IUV preamp and the URL is http://sites.google.com/site/rxpreamps/. You can download my simple artwork for the circuit board on my website (at the bottom of the page), and I just used a Dremel tool to make the traces. Don (wd8dsb) On Sat, Aug 29, 2015 at 3:26 PM, Jim wrote: > Martin is the latest incarnation of the infamous W7IUV preamp? and do you > know anyone that has PC boards before I reinvent the wheel and make another > one? > Jim WA3MEJ > > - Original Message - > > Message: 10 > Date: Fri, 28 Aug 2015 23:53:10 +0200 > From: Martin Kratoska < mar...@centrum.cz > > To: topband@contesting.com > Subject: Topband: W7IUV preamp > Message-ID: < 55e0d846.3070...@centrum.cz > > Content-Type: text/plain; charset=windows-1252; format=flowed > > The latest version 6 > > http://www.okdxf.eu/files/preamp_r60.pdf > > 73, > Martin, OK1RR > > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: rx preamps
Martin is the latest incarnation of the infamous W7IUV preamp? and do you know anyone that has PC boards before I reinvent the wheel and make another one? Jim WA3MEJ - Original Message - Message: 10 Date: Fri, 28 Aug 2015 23:53:10 +0200 From: Martin Kratoska < mar...@centrum.cz > To: topband@contesting.com Subject: Topband: W7IUV preamp Message-ID: < 55e0d846.3070...@centrum.cz > Content-Type: text/plain; charset=windows-1252; format=flowed The latest version 6 http://www.okdxf.eu/files/preamp_r60.pdf 73, Martin, OK1RR _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: KD9SV-OK1RR relays ???
Doug - Your FT-747 only has one antenna input. It does not have a second receiver. It doesn't even have a receive-only antenna input. You cannot transmit and receive at same time. Why do you need a "front end saver"? If you are adding an outboard relay keyed from the amp control line of the FT-747 to allow you to have separate transmit and receive antennas, that's great. Any old relay with less than 10ms make/break time will work fine there. You still don't need a "front end saver", because your rig still cannot be hooked to both transmit and receive antenna at same time. Tim N3QE On Sat, Aug 29, 2015 at 12:15 PM, Douglas Ruz (CO8DM) wrote: > Hi Martin, OK1RR, > > I tried email direct to you but it was not possible. I am sorry about the > other member of the list. > > It is about the FRONT END SAVER relays: > > I have two different relays here and i would like to know if i can use one > of them in > your design: > > I have HFD2 Subminiature DIP relay: > -Matching standard 16 pin socket. > -DPDT > -100 million operations > - Operate time 4ms and release time 3ms. > -Capacitance: Contact to coil 5pF and contact set to contact 1,5 pF > > I have also HFD41 relay: > -SPDT relay > -10 million operations > -Operation time 10mS > -Not sure about capacitance. > > Maybe i have to RE-DESIGN the PCB but that is very easy. > > Any idea???...Thanks, > > 73Douglas, CO8DM > > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: KD9SV-OK1RR relays ???
Is there a reason to favor relays over taking a pin diode to ground to short the input during tx? Art NK8X ᐧ On Sat, Aug 29, 2015 at 2:31 PM, Martin Kratoska wrote: > Hi Douglas, > > I am sorry to tell you that none of the relays you have is good for the > front end saver. They are usual small signal relays but a reed relay should > be used. The most important thing is not the capacitance (assumed that the > front end saver is used on 160, 80 and possibly 40 m), but the switching > times. > > I would recommend to take part in a group buy. AFAIK David, G3WGN, > organized a group buy/PCB fabrication of 80 units, possibly he may have > rests for sale. > > 73, > Martin, OK1RR > > Dne 29.8.2015 v 18:15 Douglas Ruz (CO8DM) napsal(a): > > Hi Martin, OK1RR, >> >> I tried email direct to you but it was not possible. I am sorry about >> the other member of the list. >> >> It is about the FRONT END SAVER relays: >> >> I have two different relays here and i would like to know if i can use >> one of them in >> your design: >> >> I have HFD2 Subminiature DIP relay: >> -Matching standard 16 pin socket. >> -DPDT >> -100 million operations >> - Operate time 4ms and release time 3ms. >> -Capacitance: Contact to coil 5pF and contact set to contact 1,5 pF >> >> I have also HFD41 relay: >> -SPDT relay >> -10 million operations >> -Operation time 10mS >> -Not sure about capacitance. >> >> Maybe i have to RE-DESIGN the PCB but that is very easy. >> >> Any idea???...Thanks, >> >> 73Douglas, CO8DM >> >> >> _ >> Topband Reflector Archives - http://www.contesting.com/_topband >> >> > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: KD9SV-OK1RR relays ???
Hi Douglas, I am sorry to tell you that none of the relays you have is good for the front end saver. They are usual small signal relays but a reed relay should be used. The most important thing is not the capacitance (assumed that the front end saver is used on 160, 80 and possibly 40 m), but the switching times. I would recommend to take part in a group buy. AFAIK David, G3WGN, organized a group buy/PCB fabrication of 80 units, possibly he may have rests for sale. 73, Martin, OK1RR Dne 29.8.2015 v 18:15 Douglas Ruz (CO8DM) napsal(a): Hi Martin, OK1RR, I tried email direct to you but it was not possible. I am sorry about the other member of the list. It is about the FRONT END SAVER relays: I have two different relays here and i would like to know if i can use one of them in your design: I have HFD2 Subminiature DIP relay: -Matching standard 16 pin socket. -DPDT -100 million operations - Operate time 4ms and release time 3ms. -Capacitance: Contact to coil 5pF and contact set to contact 1,5 pF I have also HFD41 relay: -SPDT relay -10 million operations -Operation time 10mS -Not sure about capacitance. Maybe i have to RE-DESIGN the PCB but that is very easy. Any idea???...Thanks, 73Douglas, CO8DM _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Folded CounterPoise ???
Douglas, My 160 meter antenna is also located in a corner. I put my FCP up along the two intersecting fences, such that there is a 90 degree bend, right at the center of the FCP. It works just fine in this configuration. So, if you are able to use a 90 degree installation of the FCP, give it a try - it ought to work for you as mine did for me. 73, Jim Jim Bennett / W6JHB Folsom, CA > On Aug 29, 2015, at 9:06 AM, Douglas Ruz (CO8DM) wrote: > > Hi, > > Originally, the FCP is connected in the center (33ft each side for > 160m)...Did somebody try connect it at one END ???. > > Probably i will install my vertical in a corner of my property and some > neighbours houses do not allow connect the FCP in the middle. > > any idea? > > Thanks, > > 73Douglas, CO8DM > > "No creo que haya alguna emoción más intensa para un inventor que ver alguna > de sus creaciones funcionando. Esa emoción hace que uno se olvide de comer, > de dormir, de todo." - Nikola Tesla > > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: KD9SV-OK1RR relays ???
Hi Martin, OK1RR, I tried email direct to you but it was not possible. I am sorry about the other member of the list. It is about the FRONT END SAVER relays: I have two different relays here and i would like to know if i can use one of them in your design: I have HFD2 Subminiature DIP relay: -Matching standard 16 pin socket. -DPDT -100 million operations - Operate time 4ms and release time 3ms. -Capacitance: Contact to coil 5pF and contact set to contact 1,5 pF I have also HFD41 relay: -SPDT relay -10 million operations -Operation time 10mS -Not sure about capacitance. Maybe i have to RE-DESIGN the PCB but that is very easy. Any idea???...Thanks, 73Douglas, CO8DM _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Folded CounterPoise ???
Hi, Originally, the FCP is connected in the center (33ft each side for 160m)...Did somebody try connect it at one END ???. Probably i will install my vertical in a corner of my property and some neighbours houses do not allow connect the FCP in the middle. any idea? Thanks, 73Douglas, CO8DM "No creo que haya alguna emoción más intensa para un inventor que ver alguna de sus creaciones funcionando. Esa emoción hace que uno se olvide de comer, de dormir, de todo." - Nikola Tesla _ Topband Reflector Archives - http://www.contesting.com/_topband
