Archive for July 2007

Used Ham Equipment

July 16, 2007

Once more I have some new experiences regarding this subject.

I recently bought a new (new to me) used radio. After using it for a week I discovered that it drifts in frequency, hums, and most recently has a bad output transistor.

No big deal. The transistor was replaced, the filter capacitors were reformed, and the regulator was rebuilt. Now it performs as it should, but the experience has verified a lesson that has been learned and re-learned since I first became interested in Ham Radio in the summer of 1959.

People do not sell used equipment that is in mint condition. There is no such thing. In fact most equipment that is offered for sale is being sold because there is something wrong with it. The flaw may only be minor but it often requires more to repair the flaw than the radio is worth.

Now, I am not saying that people are knowingly dumping used equipment that is defective. Some sellers may not realize their stuff is defective. They just know they want something better and are not too interested in finding out if the old stuff could be made to work better if it were in better repair. So, they sell it. There are no exceptions that I have seen in the many years I have been dealing in used equipment.

Basically, if it is being sold, there is something wrong with it. People (especially hams) do not sell stuff that is working fine and is doing the job. At least that has been my experience and I do not believe that I am the only person who has had this experience.

So, before you lay down top dollar for that mint, 50 year old radio, remember that it might be a piece of junk. If you can try it out before you buy it, do that. In most cases that is not possible so you take your chances. Just make sure you don’t offer more than you would be willing to pay for a radio with some minor problems and then only if you are good at repairing things.

Otherwise head to your local ham store and buy something that has a warrantee.

Bottled Water

July 16, 2007

Looks like people are becoming more and more desperate for news. Now one of the hot topics is the pros and cons regarding bottled water. Why not just drink tap water?

In our area the summer brings algea growth to the lake that supplies us with water. The plants give the water a bad taste. We used to buy bottled water and used two of those 50 gallon jugs a month. Then we discovered Britta pitchers.

The Britta filtration system works for us. It works very well. It conditions tap water to the point of where it is drinkable. So, we still use bottled water but it is bottled by us in our kitchen and consists of Britta filtered water poured into water bottles we have saved for this purpose.


July 16, 2007

VOIP stands for voice over Internet Protocol and the capability has been around as long as the internet. In its basic form VOIP allows you to ‘talk’ over the internet. All that is required is a sound card equipped with speaker and microphone. Free software such as Skype takes care of the interface in the computer and all a user needs is the IP address of the person he wishes to contact. Of course, both parties need to be similarly equipped and using Skype.

Skype is a very basic VOIP software and has very limited application to normal telephone communications or telephone numbers. However, with additional effort VOIP can replace normal telephone service.

DSL is a broadband application that normally requires a telephone line. The DSL broadband connection operates independent of normal telephone use. You may use the telephone normally while using DSL at the same time. DSL is fast enough to support VOIP but since you need basic telephone service in order the get DSL, there is no need to have basic telephone service in addition to VOIP.

VOIP is more attractive than normal telephone service in that it can be far more economical. Basic telephone service averages about $30 a month as compared to basic VOIP service at about $20 a month. VOIP is cheaper but it is also more capable. All those extra features that the phone company likes to sell as optional extras are included in the basic VOIP setup. Also included in basic VOIP is domestic long distance. No extra charges for long distance calls made to locations in the continental U.S. So, assuming you need lots of optional extras and are a heavy user of long distance calls, the VOIP compares very favorably against a normal monthly telephone fee as high as $50.

However the real savings is obtained by using VOIP and CABLE to replace normal telephone service and DSL. When you consider basic DSL at $30 a month, combine that with basic telephone at $30 a month, it compares on par with basic cable modem at $40 a month combined with VOIP at $20 a month. The costs are about the same unless you add in another $20 a month for VOIP over DSL in the first example.

Never mind that you get additional functionality with VOIP regardless of where it is used, would you rather pay $80 a month for DSL, Phone, and VOIP or $60 a month for CABLE and VOIP. Both solutions offer the same features but the DSL, VOIP solution is $20 a month more expensive.

Both solutions will save on long distance charges but why throw away an additional $20 a month?

Imagine my surprise when a well known ISP began to bundle DSL and VOIP services. Evidently they are betting that most consumers are not smart enough to avoid throwing away $20 a month.

Solid State Exciters, Amps, and Matching

July 13, 2007

I know a diagram would help explain this subject and maybe later I will add a diagram. For now I will attempt to describe the problem using words. You know, word problems. Like the ones you used to solve in high school?

Consider the transmit problem. The antenna or antenna system is at 50 ohms. No problem there. Just connect it to the amp output. The problem comes when we connect the exciter to the amp input. The amp input is not at 50 ohms on all bands or even over the extent of a band like 80 meters. This causes us an immediate problem with solid state exciters. The mismatch reduces the output of the exciter as the exciter reduces power to protect its output transistors. If your amp needs 100 watts drive and the mismatch results in a 2:1 SWR, the exciter may only provide 50 watts max and the amp will not develop full power.

The intuitive solution is to use an antenna tuner or matching device between the exciter output and the amp input. Adjust this to get a 1:1 SWR into the amp input and you will get max output from the exciter as well as the amp.

This solves the transmit problem but what about when we switch back to receive? The antenna system is still at 50 ohms but the exciter output has been matched to whatever the amp input happens to be. We do not know what that is but we do know it is not 50 ohms. So now we have that old 2:1 SWR hurting us on receive instead of transmit.

Can’t really retune the matching because we need power to run the SWR meter to do that and that will get us back to a transmit condition.

The solution to this problem is to include the extra matching device into the amp and make it part of the amp input circuit.

That solution may be impossible to implement, particularly if the additional matching network is internal to the exciter in the form of an automatic antenna tuner. Realize that if that is indeed the case, we would not have experienced the power starving condition we attempted to correct. However, we would still be subject to the mismatch on receive.

Is the receive mismatch really significant? Or are we talking about one silly db among hundreds? A fair question but it arises from a possibly dangerous precedent. A tendency to cut corners is never good. Eventually, all those round corners will add up to become significant even if the effects of each individual compromise can be ignored.

At this point we might resign ourselves to solve the problem rather than merely treat the symptom. How about we adjust the input tuned circuit in the amp. If we are talking about 80 meters, that may not be possible. 80 meters is wide enough to allow us a match in the CW portion or the SSB portion but not both. So we are back to incorporating the additional matching device into the amp input circuit. Note that we will need an additional matching device even if the exciter has a built-in auto tuner unless we can access the input and output of the auto tuner independently of the exciter connections.

Since we probably will not be able to locate the extra matching device inside the amp, we will need to locate it outside the amp and use some creative cabling requiring two additional coax connectors be installed at the amp input.

One of these connectors becomes the internal connection to the input of the amp. This becomes the place to connect the output of the extra matching device. Label this one ‘internal amp input’.

The second connector is wired to the input portion of the antenna change over relay. That terminal to which the amp input was originally connected. This becomes the place to connect the input of the extra matching device. Label this one ‘change over amp input’.

For configurations in the future where an extra matching device is not needed or desired, these two additional connectors can be jumpered with a short length of coax and the amp is restored to its original condition.

By adding the two additional connectors we have taken the matching device out of the common T/R antenna path. We now have a receive path that is separated from the transmit path. We no longer suffer a mismatch on receive by adjusting for a match on transmit.


July 11, 2007

I recently purchased a used Atlas 210x transceiver. This particular radio has an IF of 5595 khz. I understand earlier radios had IFs of 5520 khz and later radios had IFs of 5645 khz. I have no idea as to why the IFs were changed from one series to another. I guess I really do not care. My particular radio appears to have a serial TH4976. Or maybe that is a date code. The 49th week in 1976?

I bought it because I have always wanted one of these little transceivers. These first came out in the early 1970’s They commanded a list price of $665. The base console/power supply was another $250. The VOX option was available for around $200. This radio has all three and cost me $170. Twenty dollars of that was for shipping.

It measures 9.5 inches wide, 7 inches deep, and 3.5 inches high. These measurements not including heat sink. The massive heatsink/final amp combination add another 2 inches to the depth dimension. It is small. Maybe even tiny by 1970 standards especially when you consider that it sports 5 ham bands and an OUTPUT power of 80 watts. Best of all it still works. Quite remarkable for a 37 year old radio. I suspect it really is only 20 years old but that does not make it any less remarkable.

There are a large amount of modifications published for this radio. Some of the mods are trivial, others are serious. None of them apply to my radio because it is of later manufacture.

The receiver is very basic using a diode ring first mixer and a diode ring product detector. No receiver rf amplifier. The antenna is connected directly to the mixer input after going through some double tuned input circuits. Single conversion, the IF is 5595 khz. Most of the gain is produced in the IF section. The audio output is an LM380 for about 2 watts maximum output to a three inch, 4 ohm speaker.

Sensitivity is better than .5 microvolts on all bands. IMD is around 80 db with weak signal performance at -130 db. Not as good as the best but far better than the worst.

The AC power supply in the console is of unusually clever design. It is about one third the size of and ICOM or Kenwood supply delivering the same power. The secret is that Atlas does not regulate the power to the final transistors. They are allowed to run open off whatever the transformer/fullwave diodes/capacitor filter section limits. Voltage to the finals is typically around 17 volts when run off the AC supply.

A second part of the supply is low current and regulated, but instead of using an expensive three terminal regulator, it used a cheap TO-220 power transistor with base biased to a 13 volt zener.

The back of the radio has two banana jacks for power. One is the higher current and the other is the lower current, regulated connection.

For mobile application both of these connections are connected in parallel and are run from the vehicle battery terminals.

It sports four plug-in printed circuit boards. The circuit board connectors are of high quality as is most of the mechanics of the radio. It looks good enough to meet military specifications.

The output is SWR protected. That feature protects the output transistors by reducing power if the SWR gets much above 2:1. At an SWR of 2:1 power is reduced to half maximum.

It is a very basic but nice radio. Audio quality is exceptional on receive and transmit because it uses a 2700khz filter. The filter has a 1.6 shape factor and extremely sharp skirts. This filter and the double tuned input circuits are the only selectivity related components in this radio but they appear to be more than adequate.

Although it will do CW it is primarily designed for SSB. It is also capable of increased power output by replacing the 50 volt final transistors with 80 volt units at a cost of 50 bucks or so. The output power then goes to about 117 watts on 80 meters with no need to modify the power supply.

I sure could have used this thing 20 years ago. Guess I will have to make up for lost time.


July 11, 2007

This tube requires an SK800 socket with chimney. Last time I checked a ceramic chimney was priced at about one hundred bucks. Since I only paid 38 bucks for the socket and the good 4CX1000 was a gift, I find it difficult to pay the going rate for a chimney.

Time to research some sheet silicone rubber. Try to cut it cleverly to make it into a cone. Then use hose clamps to attach it to the tube.

I still think the 4X811 route is the better one to take, but if you already have all the required parts, especially the expensive parts, then a 4CX1000 solution may be the way to go even if the best you can do is provide 2500 volts of plate high tension.

The only things I need are a good high voltage plate capacitor, a plate blocking capacitor, and an antenna loading capacitor.

The advantages are a nearly indestructable amp with a power reserve that will never be used.

Jury Duty

July 10, 2007

Every few years I get a summons in the mail inviting me to go to a courthouse for jury duty. This has been going on for over 30 years and it is always the same drill. If you go, you will be sent a check for 6 dollars to offset your expenses. If you don’t go, you will be sent a fine of up to 500 dollars to fill the coffers of the greedy. Least I forget, you are also offered the opportunity to donate your meager pittance to some childrens charity that no one has ever heard of. Peachy, just peachy.

Lately the renumeration has increased to 40 dollars a day but only if you are assigned to a trial and then only on the second day of your tour of duty.

Six dollars is not much, but if you ride mass transit, it leaves you with enough money to have a 6 inch subway sandwich for lunch.

Trust me, mass transit is the only way to go. If you take your car, it will cost you at least one gallon of gas and probably two. That alone eats up your six dollar pittance. Then they have the audacity to offer you a discount parking fee of only 3 dollars, but you have to get your ticket validated before 4:30.

Never mind that the time you spend on jury duty is really donated under duress. If you are self employed or your employer does not pay for time spent off the job, you end up with a shorted check for the days you volunteer for jury duty.

Jurors are subject to gross mistreatment and I think it is because they are indentured servants. The government has no reason to ensure that a jurors time is not wasted. In many cases a jurors time is wasted to the point of absurdity. A juror receives no consideration and is subjected to conditions that support the convenience of the court.

All the while you are being abused there are some lawyers and judges that are heaping praise on you for allowing it. They go to great lengths to make lovely speeches about how much they appreciate your service. Unfortunately it is only lip service. They do not show any compassion or real appreciation of what they ask of a juror.

Lets look at a typical day of a juror.

The court is downtown and you are to be in the jury room by 8:30 in the morning. If you are late, they consider you the same as not even showing up. This means you have to get up at around six to be ready to leave around seven or seven thirty to get there at eight, in plenty of time to be counted present.

You are told to take a seat in a large jury room. There you sit and wait while all the jury duty slips that were turned in are sorted. This could be over 1000 slips. Once that is done we wait until there is a call for jurors from one of the courts. That normally does not happen until later because the courts don’t start business until 9:30 or later. You see, they are special. They are worth more than 6 dollars a day.

Generally this means that it can be 10:00am or later before any juror gets assigned to go to a courtroom. Meanwhile, every two hours or so you are allowed a half hour break. You can move to sit in the seat next to you, go to the bathroom to throw up, or buy a soft drink from a machine charging $1.50 a can.

Sometimes jurors get assigned to go to a courtroom that is not in the building to which they have been summoned. When that happens they are told they can drive to the new location. Those who did not bring their cars but rode mass transit may ride mass transit back home and get their cars! (see what I mean about abuse?). Or, you can come back in an hour and a half and transportation will be provided.

Having used mass transport to get there I waited for transportation to be provided. They brought up a van that was designed to transport prisoners. It was a hot crowded, caged, affair. A jail on wheels. A van normally designed to hold 9 passengers comfortably was stuffed to overflowing with 13 prospective jurors. A sedan was also provided because there were more than 13 jurors.

Arrival at the second location was around 1:30 and we were all (all 60 of us) standing in a crowded hall outside the courtroom waiting on the next humiliation. Finally, nearly 8 hours after we had risen on that unlucky morning, we were ushered into the courtroom. None of us were in a particularly good mood having been subject to an 8 hour waste of time that could have been avoided. Why not just have us report to the second location at 1PM instead of summoning us to a court that did not need us. Oh, but that would take planing and there is no sense in planning when it comes to the use of a jurors time. After all, they don’t have a choice and are only worth 6 bucks a day.

It took another three hours in the courtroom with defense and prosecution asking loads of questions and the judge admonishing us to judge according to what the law prescribed. I doubt very seriously that the jurors in my group had any idea of what the law was, much less what it prescribed.

We all took oaths to tell the truth. Lawyers also take oaths but I am not sure it is to tell the truth. The only person in the court that I have never seen take an oath to tell the truth or otherwise is the judge. I guess when you become a judge you can’t lie. Or you are allowed to do as you please without consequence.

I got the feeling that justice took second seat to following procedure, but I am not sure how that could be corrected without making justice the personal play toy of the lucky few.

As luck would have it my answers to the questions fell short of what was needed. Therefore I was not selected. Seems that they were more interested in selecting folk eager to follow instructions (the law) rather than allow for people to act on their own definition of what is moral and just. I can see that. That is understandable.

We sometimes hear the high and mighty proclaim that we are a nation governed by laws, not men. The next time you hear that consider this. Our laws are made by men. Furthermore, if you really believe that all men are created equal, then the lawmakers are not any smarter than those who are expected to follow the laws that are made. In addition, we all know how devisive some lawmakers can be. Just look back on the so called immigration bill of 2007.

Me and the others who were not selected waited for nearly 45 minutes in the parking lot for the van to appear to take us back to our original point of departure. Same van, same crowding.

By 5:45 we were back at the original courthouse. By 6:08 I had just missed catching the train back home. Waited another 15 mins for the next train and was back at the neighborhood station by 6:40.

Pretty much a 12 hour day of hurry up and wait. A complete waste of time while being abused by Big Brother at every turn. I would not be at all surprised to discover that was the way the pyramids were built. Aliens had nothing to do with them. It was all slave labor obtained through a jury summons.

One thing I noticed that surprised me was that at no time did anyone think to verify my identity. They merely took the stub of my summons that I had filled out a day earlier and assumed that I was a qualified juror because I did not claim any exemptions or disqualifications.

It would be worth 50 maybe even 100 bucks to hire a surrogate to serve in your place. Not sure what would happen if you were discovered but chances of that are slim enough to tempt one to try it.