I visit the St. Louis, MO area a few times a year since my brother lives there. He tells me that two of the ham radio clubs in the area have "members only" repeater systems. That is, you can't use the repeater unless you are a member of the club. If they don't recognize your callsign and you aren't on the club roster, you might get told to get off the repeater by a club member! In my opinion, this practice is totally wrong. I thought repeaters were there to be used by ALL radio amateurs. I know that having a "members only" repeater system is totally LEGAL, but it does nothing but alienate hams who are not club members and creates a "clique" atmosphere, none of which are beneficial to the ham radio community.
Some would think that the term "closed" repeater system means that it uses a PL tone to gain access. This is not what I am referring to. There are many repeaters with PL tones and this feature keeps other repeaters from keying up one that may be on the same frequency especially during tropo openings. There is NO problem with that. I am highly in favor of it. Repeaters that have PL tones are not really "closed" systems since most VHF/UHF rigs have PL in them anyway.
The excuse given for clubs who won't let non-members use them is that the repeaters cost money to install and maintain and that it should only be used by members who support it with their dues and contributions. My response to that is that if they did not intend for all hams to have access to it, then they should not have built it in the first place. It is going to be sitting there sucking electricity regardless of who uses it anyway. So what is the difference?
I feel sympathy for the new ham who just got his/her license and finds out that the local repeaters are closed to non-members. How do you think that makes him/her feel? Like an outcast! Would he/she feel compelled to join a club with a "members only" repeater system? I bet they would think twice about it, don't you? He or she would be thinking "What a bunch of stuck-up snobs!" If a radio club has any kind of conscience at all, it would not want that kind of label.
The exclusion of non-members in the use of a repeater system would be like having Thanksgiving dinner and telling your in-laws that they can't come because they are not blood relatives! That would certainly cause a family feud!
Lets say a ham has some kind of personal emergency on the road and his cell phone battery has died. He reaches for his dual band radio to call for help. Would he get "bad mouthed" for trying to use the "members only" repeater that is the only one he can reach? What then?
I really can't think of any reason why any club would need to have a "members only" repeater system. The chances that any ham would use the repeater wrongly are pretty close to slim and none. We are supposed to be a "family" of communicators. If we ex-communicate or shun non-club members, it pretty much defeats our purpose. Don't you think?
I'll be damned if I am going to let any radio club tell me that I can't use their repeater if I so choose. The airwaves do not belong to any certain group. They belong to ALL of us! I have been going to hamfests in the St. Louis area for many years and I have helped support the radio clubs with the money I spend on tickets and raffles as have many other hams. The radio clubs should at least show some kind of gratitude for that support to the general ham community by keeping their repeaters open to all hams, regardless if they are club members or not.
Friday, February 25, 2011
Tuesday, February 1, 2011
Radio Frequency Interference In The Ham Shack
I am sure many of us have had RFI in the ham shack at some point. There have been problems with RFI getting into speakers and headsets, RF bites when we touch metal microphones, etc. These can all be quite annoying.
However, these things can be easily fixed. One general rule of thumb that I use is that if any connector is loose, it can vibrate and act like a crystal in the presence of strong RF and emit RFI. So the first thing you should make sure of is that all audio and coaxial cable connectors are absolutely tight.
Using a good shielded audio cable is essential to making your speaker system and other audio routing RF proof. Never use simple audio coax with center conductor and shield. Use two conductor (red and black wires) cable with a good copper braid shield and foil shield under the braid. You need both the "hot" wire and ground wire to be shielded.
When soldering PL-259 coax cable connectors on, here are some tips. When using coax that has a stranded center conductor such as RG-2013, always coat the center conductor with a bit of solder to keep the strands together. One little stray whisker in contact with the connector barrel can cause a coax connector to be shorted. When soldering the connector, always file the nickel plating off the area around the 4 little holes in the barrel. This will make the solder flow on much better. I use a 200 watt soldering gun. I have a set of Swedish files to do this with and they work great. They come in a set of 5 or 6 in a plastic pouch and are available in any hardware store. When soldering the holes shut, get your tip down on the top edge of the hole, feed some solder on to the tip and pull the tip toward you in a downward sweeping motion. This works well. Do not try to clamp the connector into a vise before soldering because this will just act like a heat sink. Gently clamp the coax cable itself into the vise instead, leaving about 1 1/2" of cable sticking out past the connector. The advantage of soldering the 4 holes shut is that it somewhat keeps moisture out and it keeps small amounts of RF from leaking out. I used to get RFI in my headphones and speakers a lot until I started soldering the 4 holes shut on all my coax connectors.
Using a good quality solder is essential for making good RF connections. Kester "44" solder has been a "gold standard" of the industry for many years. Another good brand is Multicore 500G which is a 60/40 blend of tin and lead. Alphametals also makes some good solder.
Some hams use ferrite chokes for RFI suppression. This is a good "band-aid" approach for a quick fix. I have never had much luck with them. The drawback is that you need to wrap as much wire around the choke as possible in order to get the full effect. Then you have a big old wad of wire and choke laying on your ham desk or shelf, sticking out like a sore thumb. Of course, if it is hidden behind equipment, nobody will see it, but really you need to find the source of the problem.
RFI can be passed on through the house electrical system by your station power supply! I had a regulated 35 amp power supply that I used for several years until I bought a Tokyo Hy-Power HL-450B amplifier which required a 60 amp switching power supply. Prior to this, my HF radio transmissions would always blank out my Davis Instruments weather station display unit. After installing the switching power supply(HP-460), the problem went away. Figure that one out!
Update 9-2-18: Since writing this, I have installed an MFJ-2990 vertical antenna and my RFI problems have gone away. I used LMR-400 coax and greatly improved my grounding system. Now, I can use my amplifier at full output without causing QRM to anything inside or outside the house.
I hope this blog helps in some way. I appreciate any comments you might have.
73,
John Gercken, AA9UF
However, these things can be easily fixed. One general rule of thumb that I use is that if any connector is loose, it can vibrate and act like a crystal in the presence of strong RF and emit RFI. So the first thing you should make sure of is that all audio and coaxial cable connectors are absolutely tight.
Using a good shielded audio cable is essential to making your speaker system and other audio routing RF proof. Never use simple audio coax with center conductor and shield. Use two conductor (red and black wires) cable with a good copper braid shield and foil shield under the braid. You need both the "hot" wire and ground wire to be shielded.
When soldering PL-259 coax cable connectors on, here are some tips. When using coax that has a stranded center conductor such as RG-2013, always coat the center conductor with a bit of solder to keep the strands together. One little stray whisker in contact with the connector barrel can cause a coax connector to be shorted. When soldering the connector, always file the nickel plating off the area around the 4 little holes in the barrel. This will make the solder flow on much better. I use a 200 watt soldering gun. I have a set of Swedish files to do this with and they work great. They come in a set of 5 or 6 in a plastic pouch and are available in any hardware store. When soldering the holes shut, get your tip down on the top edge of the hole, feed some solder on to the tip and pull the tip toward you in a downward sweeping motion. This works well. Do not try to clamp the connector into a vise before soldering because this will just act like a heat sink. Gently clamp the coax cable itself into the vise instead, leaving about 1 1/2" of cable sticking out past the connector. The advantage of soldering the 4 holes shut is that it somewhat keeps moisture out and it keeps small amounts of RF from leaking out. I used to get RFI in my headphones and speakers a lot until I started soldering the 4 holes shut on all my coax connectors.
Using a good quality solder is essential for making good RF connections. Kester "44" solder has been a "gold standard" of the industry for many years. Another good brand is Multicore 500G which is a 60/40 blend of tin and lead. Alphametals also makes some good solder.
Some hams use ferrite chokes for RFI suppression. This is a good "band-aid" approach for a quick fix. I have never had much luck with them. The drawback is that you need to wrap as much wire around the choke as possible in order to get the full effect. Then you have a big old wad of wire and choke laying on your ham desk or shelf, sticking out like a sore thumb. Of course, if it is hidden behind equipment, nobody will see it, but really you need to find the source of the problem.
RFI can be passed on through the house electrical system by your station power supply! I had a regulated 35 amp power supply that I used for several years until I bought a Tokyo Hy-Power HL-450B amplifier which required a 60 amp switching power supply. Prior to this, my HF radio transmissions would always blank out my Davis Instruments weather station display unit. After installing the switching power supply(HP-460), the problem went away. Figure that one out!
Update 9-2-18: Since writing this, I have installed an MFJ-2990 vertical antenna and my RFI problems have gone away. I used LMR-400 coax and greatly improved my grounding system. Now, I can use my amplifier at full output without causing QRM to anything inside or outside the house.
I hope this blog helps in some way. I appreciate any comments you might have.
73,
John Gercken, AA9UF
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