Archive for February 2009

Drake T4XC

February 16, 2009

Yup, that is my main transmitting rig. Older than sin but still works and looks good. It is also not stock, or maybe some would say ‘mint’. It has been modified in several ways but the main mod is a conversion to use 6146Ws in the final cage. A minor mod is the addition of a fan to cool the finals but that has been disconnected because I got tired of listening to the fan noise. Not that it was all that noisy but I could tell it was on because the shack is otherwise quiet as a tomb. I finally realized that the finals would not be on but for a few minutes and even then would not be running flat out so the additional cooling was not really necessary and I would appreciate the quiet much more.

This transmitter gets used at least once a week on 75 meter SSB.

Recently I found an additional mod for the Drake T4X series of radios. An audio modification claiming to make the audio easier to listen to. Make it more natural sounding and of HI-FI quality. Well, I never have taken much stock in striving for HI-FI on the ham bands but I took an interest because the mod included a simple addition of capacitors in the mic amplifier circuit.

Those not familiar with Drake equipment may not realize the construction and difficulty in executing any mods of this nature. All the T4 series of Drake radios uses small PCB boards that are mounted on-edge to the chassis. This makes it difficult to even see what is on the boards much less change anything.

It took the better part of a day just to find the manual. Then the entire afternoon to find the parts in question. The idea was to add capacitance to existing capacitors to improve the frequency response of the mic amp at the lower end of the audio frequency scale.

Turns out that my transmitter did not need the extra capacitors. It already had sufficient capacitors installed. Guess maybe it was a later model. What this excercise did disclose was that the 6AU6 AM modulator was disconnected from its PCB and a 100k resistor had been broken on another PCB. Obviously these deficiencies did not effect the operation on SSB lower sideband in the 75 meter band. Still, these deficiencies needed to be corrected and they were.

So now I can use the transmitter on AM if I want. That probably will not happen but it puts the spotlight on what might be problematic in the future. Every indication was that the lead that had been disconnected was due to fatigue of the wire in the soldered termination on the PCB.

Drake used solid conductor hook up wire on all their equipment. This works well but introduces the problem experienced. On installation should the solid wire be nicked even slightly before it is terminated to a connection chances are good that it will break sometime in the future if it is subject to stress. In other words, if you wait long enough, all the hook up wire in the radio will fall off when you remove the covers. Hopefully this may not happen for 500 years but I know of at least one wire connection that did not make it past 30 years.

So, although the repair was really not necessary, I am glad it was made and the rig is back to its normal self.

Dell

February 15, 2009

Sometime ago as we were doing some contract work for a startup we were provided with a Dell Dimension 8200 computer. This thing arrived with XP/home pre-installed. We used it for about a month when it finally would not boot anymore. Thinking it was a hard drive failure, we got the drive replaced, loaded win98 onto it and continued to use this machine for a number of years. Win98 was doing everything we needed done. We did not have the time or inclination to divert our resources to learning a new and much more complicated operating system when win98 was working just fine.

After this experience and after we finally took interest in the ‘new’ computer and XP we discovered that most likely the initial failure was due to us not registering the thing with Microsoft. Had we known that we needed to do that we would still have nuked XP and opted for win98. We do not need computers that require unusual attention or software that requires special treatment when such products do not provide us with features that we really need.

Recently we added new software to this machine putting a higher demand on the hardware. It finally got to the point where we needed more RAM memory to speed up the operation. We were spending too much time waiting on software. We discovered that this computer was equiped with the bare minumum or 128meg RAM and a 1.8ghz pentium 4 processor. Being a pentium 4 we decided the computer was worth keeping and investigated upgrading the RAM to 1 gigbyte.

We discovered that this particular machine was designed to use PC800 memory. PC800 memory is extremely expensive. Probably because Dell seems to be the only company that uses it. The cost of one giglebyte was a shade over $300 or about twice what the entire computer was worth. Not only that, but you could not buy just one stick of PC800. It needed to be used in pairs, a situation what was entirely unacceptable when compared to other options.

So we bought a giglebyte of PC-100, installed it into an older, slower Dell and moved everything to the older machine. Even though the older machine had a CPU running about 40 percent the speed of the 8200, with the extra memory it was still faster than the 8200 with its bare minimum of RAM.

Meanwhile the 8200 was retired to hobby use running Debian Linux after we tried unsuccessfully to install XP professional on the machine.

Recently we upgraded the hard drive on the 8200 and discovered that, now, XP would install normally. How opportune, since now we had need for another machine running XP. We had since discovered that XP did offer some MultiMedia features that were desirable. Even so we still had the RAM memory limitation and PC800 memory was still priced up in the stratosphere. However we did find an ASUS motherboard designed for a socket 478 system for under $50.

The ASUS motherboard also used the pentium 4 but allowed us to use PC-3200 RAM of which we had an extra giglebyte stick available. So, by replacing the problematic Dell motherboard, we neatly solved the RAM memory problem for considerably less than it would have cost to buy more PC800 memory.

Not only that, but the ASUS motherboard offered some significant advantages over the, now obsolete, Dell motherboard. The ASUS had on board NIC, Video, Sound, and USB ports as well as IDE and ATA controllers. We would probably still use our ATI Radeon 9250 video card but we could retire the sound card and the NIC.

True, the Dell motherboard also had on board sound but that cratered about two weeks into using it.

So we were able to salvage the Dell but we are also pretty much burned out on Dell. We would go out of out way in the future to avoid them.

Our main reasons for this attitude are as follows:

1. Dell did not bother to make clear the need for registering the XP software. Their support was not just inadequate, it was brainless and problematic. Instead of working toward a solution to the problem they added to the problem by providing a blank hard drive requiring the user to reload software when the original hard drive had probably not failed at all.

2. The Dell computer was a marginal design. The hardware was the minimum that would work and the software was marginal as well. XP/home is less expensive than XP/pro, it is also far less useful. I guess one can appreciate that Microsoft provided a lower cost alternative to XP/pro but the lower cost alternative was close to worthless when compared to the more expensive package. They did not do us any favors by providing a somewhat crippled version of the new software even if it was more affordable from a price consideration.

3. The Dell design used the most expensive hardware available at the time. The expense was not justified. PC800 memory does not have any significant advantage over PC3200 and when you consider the difference in price, it does not make sense to use PC800. A far better solution would have been to use the extra funds to invest in XP/pro and settle on PC3200 memory.

Companies that make bad decisions in design are probably confused about other things as well. I find it unwise to support such folly.

openSUSE

February 13, 2009

Well, on the recommendation of an acquaintance I tried openSUSE 11.1.

Slick install as far as the graphics went. Sort of like Microsoft stuff but without the congrats and promise of fun ahead.

The first thing openSUSE asked for was permission to activate some swap space. Okay no problem, I let it activate some swap space. Then when it came time to copy software to the hard disk it tells me there is no space on the hard drive. HuH?

So I check the hard drive, it is only a 10gig drive, and it turns out the dummy assigned all 10gig to swap space. Things went from bad to worse from there and I finally stored the installation DVD in a very safe place.

Could be I am the dummy. Could be the hard disk was not large enough or I did not have enough memory or the hardware was too out of date or any one of a number of additional problems that are usually solved before installation by reading the minimum system requirements listed on the cover of every operating system box I have ever used. Every one except the openSUSE system. It did not come in a box. It was downloaded off the internet and the minimum system requirements could not be found.

Now I hope the installation DVD will also never be found again either.

Life is too short to waste time on buggy or user unfriendly software.

I have been doing computers for 30 years now and this is the fifth time I have run into problems with system installations. In all but two of the five cases the software was a new ‘enterprise’ release by some big-shoot firm of Linux software that had been working just fine before it was ‘enterprised’ Had problems with RedHat, Mandriva, and now openSUSE.

Sure glad God made Debian.

Lost Mind

February 11, 2009

When someone accuses you of having lost your mind, just tell them:

Its not lost. I know exactly where it is. I just don’t bother to use as much as I used to. Gives me a headache.

Then see what happens. You might be elected to office.

Heaviest Element

February 11, 2009

The Heaviest Element Known to Science:

Lawrence Livermore Laboratories has made a startling discovery in finding the heaviest element yet known to science.

The new element, Governmentium (Gv) has one neutron, 25 assistant neutrons, 88 deputy neutrons, and 198 assistant deputy neutrons, giving it an atomic mass of 312.

These 312 particles are held together by forces called morons, which are surrounded by vast quantities of lepton-like particles called peons.

Since Governmentium has no electrons, it is inert; however, it can be detected, because it impedes every reaction with which it comes into contact. A tiny amount of Governmentium can cause a reaction that would normally take less than a second, to take from 4 days to 4 years to complete.

Governmentium has a normal half-life of 2-6 years. It does not decay, but instead undergoes a reorganization in which a portion of the assistant neutrons and deputy neutrons exchange places.

In fact, Governmentium’s mass will actually increase over time, since each reorganization will cause more morons to become neutrons, forming isodopes.

This characteristic of morons promotion leads some scientists to believe that Governmentium is formed whenever morons reach a critical concentration. This hypothetical quantity is referred to as critical morass deposits. The location of Governmentium deposits is found in every state Capital. with a mother lode in Washington, D.C.

When catalyzed with money, Governmentium becomes Administratium, an element that radiates just as much energy as Governmentium since it has half as many peons, but twice as many morons.

Tornadoes

February 11, 2009

I guess spring is here already. Last night we were forecast to get rain. Then we were forecast to get thunderstorms too. I did not dwell on the forecast weather too much. After all the last time we got any significant rain, it came from a thunderstorm.

About 9pm we heard the sirens. Then came the rain followed by the wind followed by more sirens. Some folk in our area suffered damage from the tornadoes. Typical tornado in the trailer park scenario. I am convinced that trailer parks cause tornadoes.

We did not get any tornado damage. Guess maybe the sirens scared them off.

It is going to be an interesting spring.

Tube Amp

February 7, 2009

This tube amp is something suitable for use as a small computer speaker amp. Inspired by the recent discovery of the Morgan amp.

The Morgan amp is a simple three tube single channel amp using old AC/DC 5 tube radio parts.

A 50L6 output, 35Z5 rectifier, and 12SQ7 pre-amp all cobbled together to give at least an honest 1 watt of audio to a pair of simple speakers.

Cheep, cheap, inexpensive. The Morgan amp runs directly off the 120vac line. Not a safe application, but it can be made safe by using an isolation transformer, fuse, and on/off switch.

The low cost is a direct result of the simple design.

I did not have but one 35Z5 but I did discover a few 12AV6s, 50C5s, and 35W4’s. These are the miniature equivalents to the tubes used in the Morgan amp. So I decided to use them in an updated Morgan design. The only change was to replace the tubes with the ones I had on hand.

Folk who do not have a box of parts to pick from can still build this amp. The most economical approach is to find two AC/DC radios at a thrift shop or garage sale. Working or not, these radios can provide all the parts necessary to build a two channel Morgan amp. Three of the tubes in these old 5-tube AC/DC radios are used in this amp. One of the remaining tubes is an IF amplifier and the other is a mixer.

It could be argued that this amp driven by a crystal radio can provide far better fidelity reception of AM signals than the original radio. Instead of a superheterodyne style radio we revert back to a simple detector and audio amplifier. We might loose a little in selectivity and sensitivity but I doubt anyone listening to powerful local stations would notice anything but the lack of interference, noise, and squeals with the mixer gone. (Wonder why these things are called SUPERheterodynes? Most things I see with the ‘super’ label, are anything but super.)

In my design I used the goofy printed circuit mounted tube sockets found in the AC/DC radio I had. I simply cut them out of the old printed circuit board and mounted them with screws to a scrap of unused printed circuit board I had been saving. Somewhat more work than it should have been but very effective.

The housing for the amp was made from scrap pieces of redwood that had been salvaged from a demolished redwood deck. The complete enclosure is redwood and plexiglass. The plexiglass is also of the salvaged variety.

The end result is lots of noise for little cost. Actually no cost except for the time to build the thing.

You might well wonder ‘why do this’. Okay, you can buy new amplified computer speakers for under
ten dollars but then they are ten dollar amplified computer speakers. They don’t have the characteristic sound of a tube amp.

What characteristic sound? The sound of rock and roll.

All this started when tubes were cheap and amps were popular. Folk were not too concerned about how linear the sound was. Or how well a full spectrum of sound frequencies were replicated. All they wanted was something to make noise. Meanwhile, tube amp designers were not all that concerned about building expensive stuff with super good specifications. Why bother when it cost much less to build something that just made a lot of noise. Besides this is what was selling. No future in building stuff no one would buy. It was much easier to sell a cheap tube amp than a more expensive carefully engineered amp. The rock and roll crowd picked up on the cheap amps and used them. Their cheap and distorted audio gave the music a distinct flavor and rock and roll was born.

Now days real rockers can appreciate the sounds of that distinctive distortion that you can only find in music coming from a poorly designed tube amp.

So here you have it, a poorly designed tube amp for the rock and rollers.

You don’t have to dream about it. You can actually re-live the past. At least listen to the music of the past on real tube equipment.

When you can do it for no cost, why not?