Re: Topband: TX/ RX Antenna Switching
Forgot the link to Array Solutions RF Limiter / Front Load Protector (Helps to know what they call these items so you can search for them :-) i.e.. Front End Protector. http://arraysolutions.com/Products/as_rxfep.htm That's a terrible protection system. It would deteriorate almost any receiver, unless you are using a super regenerative. Back-to-back diodes by themselves are a poor enough system. They generate significant intermod with a sum of all signals at .5 volts RMS, which is a sum of signal power (from all signals) of only 7 dBm at 50 ohms or 5.2 dBm into 75 ohms. Back-to-back diodes even deteriorate performance below that threshold with most small fast signal diodes, some fast small signal diodes start to create unwanted mixing products at 0 dBm or less. Back-to-back diodes driven by minicircuits type transformers would be worse yet. I can't use minicircuits transformers on my Beverages here, because of IMD. A properly designed clamp would have no effect up to about 20-23 dBm, where it would clamp hard, and would not include easily-saturated very small core transformers. Be careful with anything that uses back-to-back diodes. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
It sounds like the DX and MFJ are out because of Watt limitations (200W?). You are misinterpreting the ratings. The ratings are for power from the transceiver sent out THROUGH the device, not transmitter power to some other system not directly connected to the device. The switches go between the radio and amplifier. This means unless you have a radio with more than 200 watts driving your amplifier, they are fine in the intended application. If you use them as a receiver line limiter or disconnect, and do not intend to transmit through them, the power rating does not apply at all because it is an external system. In that case, the power rating would depend on mutual coupling between transmitting and receiving antennas and impedances of the receiving antenna system. A power rating would be impossible to define because systems vary so much, but it would be many kilowatts even with close antennas. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
By the way Buck, there is more to this than some people will tell you. The DXE switch uses a unique RF limiter that kicks in hard at about 23 dBm. Below that level there is no intermod at all!! It will not deteriorate the receiver, like normal cheap back-to-back diode systems. If you need a receiver limiter and do not want to hurt receiver dynamic range on modern receivers, it takes far more circuitry than cheap back-to-back diodes. 73 Tom ___ Topband reflector - topband@contesting.com
Topband: PT0S Logs
According to the PT0S website, there are 9964 QSOs in the Database - Last QSOs in the Database: 1057 UTC 14 November 2012 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
Getting away from what we are discussing now (limiters) and back to the original question... it really is just a few bucks for a relay for a rig (without separate T and R jacks) at the 100W level, to add separate T and R based on the amp key line. It's ironic that for most of half a century, the ARRL handbook showed designs for T/R switches, and now those with entry level radios have to build the opposite of the T/R switch to have seperate T/R antennas :-). Tim N3QE From: Topband [topband-boun...@contesting.com] on behalf of Tom W8JI [w...@w8ji.com] Sent: Wednesday, November 14, 2012 4:25 PM To: ZR; Buck wh7dx; topband@contesting.com Subject: Re: Topband: TX/ RX Antenna Switching How do we know what it has with no schematic available? It could be $1-2 worth of parts. I recommend that nobody buy anything from DXE that does not support an at home repair. I certainly agree everyone should give out schematics. Not providing a schematic does not stop anyone from copying something, because anyone can buy one and trace it out. Not providing a schematic only makes things rough for someone trying to repair something, or trouble shoot a system. I see more and more a tendency to not provide schematics, and this is an alarming trend. This goes from my consumer gear (like my home security system) to my Ham gear. Unfortunately, this is very common these days. However, we also should not shoot from the hip and/or present things as fact or present things as something we know when we are just guessing, assuming, or making things up. This goes across the board to all topics. Tom ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Topband: 8877 Tube
Wonder if someone can help with a technical question with the amp I use on 160 meters. The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. Any help would be appreciated. 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com
Re: Topband: 8877 Tube
Bob and Paul, The 8877 has a 5 volt filament. The 3CPX1500A7 has a 5.5 volt filament. Many have been running the 8877 and 3CPX1500A7 with a Peter Dahl transformer at over 4kV and they work fine. Eimac says that the filament should be 5.0 volts +- 5% or 4.75 to 5.25 volts. This should be measured with a True RMS voltmeter. A friend had high line voltage and his actual filament voltage was 5.5 volts. He had lost several tubes with an open filament. After he lowered the voltage to 5.0 volts he has not lost a tube. He used a Varistor in the secondary to each tube. The 77SX has 2 filament windings. Price W0RI Bob, A non-issue. Many of us have been running 8877s with Ep of 4KV. For example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the specified limit of 4KV. Some owners have been converting their 8877 amps over to the 3CPX1500A7 which has a much higher rated Ep since it was designed for pulsed service. Unless someone has access to a supply of pulse-rated tubes, I think it's waste of time unless the plate supply voltage is also increased. Paul, W9AC - Original Message - From: Chortek, Robert L robert.chor...@berliner.com To: topband@contesting.com Sent: Wednesday, November 14, 2012 6:56 PM Subject: Topband: 8877 Tube Wonder if someone can help with a technical question with the amp I use on 160 meters. The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. Any help would be appreciated. 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: 8877 Tube
The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. If you are talking about Eimac, they generally obtained typical operation from a single test system under a variety of conditions. Typical operation is what Eimac found in a few test cases, and is not a limit or rigid specification. It might not even repeat out in the field. High voltage does not affect life at all in thoriated tungsten tubes (it cannot strip the cathode), and in oxide cathodes (like the 3CX1500A7) HV only affects tube life when HV gets so high it strips the protective electron cloud away from cathode. This causes cathode poisoning. (This of course assumes the tube does not arc, and a typical good 8877/3CX1500A7 will hold off 15 kV or more peak voltage so arcing is unlikely in a good tube. ) http://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
On Wed, 2012-11-14 at 23:46 +, Shoppa, Tim wrote: Getting away from what we are discussing now (limiters) and back to the original question... it really is just a few bucks for a relay for a rig (without separate T and R jacks) at the 100W level, to add separate T and R based on the amp key line. It's ironic that for most of half a century, the ARRL handbook showed designs for T/R switches, and now those with entry level radios have to build the opposite of the T/R switch to have seperate T/R antennas :-). Tim N3QE I had assumed, based on discussion, that full break-in QSK must be a requirement per the original post (which I have missed). Apparently it's not. When I switch from transmit to receive I throw ONE switch - not my key or paddles. One. No RF is generated until I do hit the key but only after the switch has been thrown. When I do that I hear several relays click in unison. It's so simple that even *I* can do it. Transmitters, receivers, and transceivers have a terminal on them somewhere to take care of the needed functions within to go from TX mode to RX mode and the other way 'round. Wire your relay(s) to switch the antenna(s) and tickle those T/R terminals. Take advantage. If your rig doesn't have such a terminal (you paid how much for it?) add one. As Tim says, a T/R relay is just too easy. Buy one with 100 NO and 100 NC contacts and have fun (evil grin). Or maybe more relays with fewer contacts. If more clues are needed I can talk more about how mine are wired now and how they have been wired in the past - best done off-list. If it turns out that full break in QSK *is* a requirement..get out the drills, hack saws, chisels, axes, and solder iron and get to work. Or get out the wallet and get a set of radios that will do what you want right out of the box. 73, Bill KU8H ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
Yes, I didn't get that right and makes sense. Only 50W on my Radio.. 1/2 power into Amp. I'm obviously not electronically edumacated (as they say in Hawaii :-).. just trying to figure out how to reach out without spending an arm/leg or hurting anything :-) I ordered the Array AS-RXFEB to try it out. It's the easiest way to install. I'm going to use the TS-570 for TX and Yaesu 987 for RX. For me, I should be able to tell pretty easily if it works or not I would think? The Beverage itself should be a nice improvement as a directional to NE (Mainland U.S.) What's the RX with and without the product attached to antenna? Can I tell a difference by ear? See an S difference? I would try 5 watts without the filter on and see what it shows? Maxed out? Try 10 watts with and without etc... I looked up the instructions for DX RTR-1 Switch and Diagram 2 is what I'd be using. 811H amp. Beverage, Amp Buffer etc... If I'm not satisfied with Array on 2nd Radio (having to adjust volume might be an annoying issue).. I think the DX is the second choice. http://static.dxengineering.com/global/images/instructions/dxe-rtr-1a-rev1.pdf I'm using a DX Eng. 4 Port Switch for Hex, 40, 80 and 160M dipole. I might go with the Cushcraft MA-160V if not satisfied with Dipole. (limited space and height issues). When everyone was trying to reach PT0S a few days ago.. I was getting clear signals from all over the U.S. East Coast was no problem 5-7 (my noise is usually around S3-4 on low Dipole - with 200ft ocean drop nearby). Not too close to city.. on point. East Coast from me is nearly 5000 miles and it was a pileup. I recorded it on phone to have friend tell me call signs (getting ready to learn CW now). Yesterday.. Noise level was S0-S1. Very quiet. Thank you!! Bryan. [CONFIDENTIALITY AND PRIVACY NOTICE] Information transmitted by this email is proprietary to Mr. Mrs. B and is intended for use only by the individual or entity to which it is addressed, or where ever the hell it ends up, and will almost certainly contain information that will offend a large portion of the population, which isn't our concern. If you are not the intended lucky recipient, or it appears that this mail has been forwarded to you without the proper authority of the Wizard of Email or Al Gore, you are notified that any thought, use, or consumption of this email is entirely your choice. In such case, Bon AppetitNote: A $.02 Internet Tax was charged for receiving this email and all funds were given to some family somewhere in America or the U.N Have a nice day. ___ Topband reflector - topband@contesting.com
Re: Topband: Vertical Array Over Uneven Ground
I cant find the button to convert that metric stuff to good old USA measurements when posted from this country(-: Subject: Re: Topband: Vertical Array Over Uneven Ground I never found a way to model an an antenna over anything but flat, level ground. Not in EZNEC+ 5.0, anyway. 73, Mike www.w0btu.com On Tue, Nov 13, 2012 at 7:41 PM, Ken Claerbout k...@verizon.net wrote: Has anyone modeled or have experience with a transmit vertical array, say a 4-square, over uneven ground? By uneven I mean a variance of up to 2 - 3 meters over the footprint of the array elements. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5394 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: TX/ RX Antenna Switching
How do we know what it has with no schematic available? It could be $1-2 worth of parts. I recommend that nobody buy anything from DXE that does not support an at home repair. Carl KM1H - Original Message - From: Tom W8JI w...@w8ji.com To: Buck wh7dx wh...@hawaii.rr.com; topband@contesting.com Sent: Wednesday, November 14, 2012 8:07 AM Subject: Re: Topband: TX/ RX Antenna Switching By the way Buck, there is more to this than some people will tell you. The DXE switch uses a unique RF limiter that kicks in hard at about 23 dBm. Below that level there is no intermod at all!! It will not deteriorate the receiver, like normal cheap back-to-back diode systems. If you need a receiver limiter and do not want to hurt receiver dynamic range on modern receivers, it takes far more circuitry than cheap back-to-back diodes. 73 Tom ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5394 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: 8877 Tube
The only problem with pushing an 8877 or the 3CPX to or over the 4KV limit is that it enhances the chance of instability. Carl KM1H - Original Message - From: Paul Christensen w...@arrl.net To: topband@contesting.com Sent: Wednesday, November 14, 2012 7:23 PM Subject: Re: Topband: 8877 Tube Bob, A non-issue. Many of us have been running 8877s with Ep of 4KV. For example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the specified limit of 4KV. Some owners have been converting their 8877 amps over to the 3CPX1500A7 which has a much higher rated Ep since it was designed for pulsed service. Unless someone has access to a supply of pulse-rated tubes, I think it's waste of time unless the plate supply voltage is also increased. Paul, W9AC - Original Message - From: Chortek, Robert L robert.chor...@berliner.com To: topband@contesting.com Sent: Wednesday, November 14, 2012 6:56 PM Subject: Topband: 8877 Tube Wonder if someone can help with a technical question with the amp I use on 160 meters. The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. Any help would be appreciated. 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5395 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
Re: Topband: 8877 Tube
The 5.5V is a ploy to get higher emission at the expense of operational life. It still has an 8877 filament. Eimac has been doing similar since WW2 with pulse versions of various tubes. Carl KM1H - Original Message - From: HAROLD SMITH JR w0ri...@sbcglobal.net To: Paul Christensen w...@arrl.net; topband@contesting.com Sent: Wednesday, November 14, 2012 8:10 PM Subject: Re: Topband: 8877 Tube Bob and Paul, The 8877 has a 5 volt filament. The 3CPX1500A7 has a 5.5 volt filament. Many have been running the 8877 and 3CPX1500A7 with a Peter Dahl transformer at over 4kV and they work fine. Eimac says that the filament should be 5.0 volts +- 5% or 4.75 to 5.25 volts. This should be measured with a True RMS voltmeter. A friend had high line voltage and his actual filament voltage was 5.5 volts. He had lost several tubes with an open filament. After he lowered the voltage to 5.0 volts he has not lost a tube. He used a Varistor in the secondary to each tube. The 77SX has 2 filament windings. Price W0RI Bob, A non-issue. Many of us have been running 8877s with Ep of 4KV. For example, the typical no-load Ep of an Alpha 77Dx/Sx amp is right at the specified limit of 4KV. Some owners have been converting their 8877 amps over to the 3CPX1500A7 which has a much higher rated Ep since it was designed for pulsed service. Unless someone has access to a supply of pulse-rated tubes, I think it's waste of time unless the plate supply voltage is also increased. Paul, W9AC - Original Message - From: Chortek, Robert L robert.chor...@berliner.com To: topband@contesting.com Sent: Wednesday, November 14, 2012 6:56 PM Subject: Topband: 8877 Tube Wonder if someone can help with a technical question with the amp I use on 160 meters. The Spec Sheet for the 8877 tube lists the Absolute Maximum Plate Voltage of 4000 Volts for the tube, and also says in typical operation the plate voltage is between 2700 and 3500 volts. In my amp (Ameritron AL-1500), the plate voltage is 3750. My question is - should I be concerned (it's clearly below the maximum but above the range that is considered typical? I just want to be sure I'm not adversely affecting the useful life of the tube. Any help would be appreciated. 73, Bob/AA6VB ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5395 - Release Date: 11/14/12 ___ Topband reflector - topband@contesting.com
