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I was listening to the Win System “tech net” on Friday evening (4/20/2012) while building a J-Pole in the garage.  A gentleman came on with a question to the net.  The question was: “I have a Yaesu FT-7X00 radio, and when I transmit, the back part of the radio near the antenna connector gets hot – should I be concerned about that?”.  Net control’s advice was nothing short of idiotic: “Your antenna is mismatched and RF power is reflecting back into your radio and heating it up.  You should cease transmissions at once and repair your antenna.”  WOW! A technical ham radio network spreading bullshit across the world!  Shame on you net control!

First, every transmitter dissipates energy in heat.  FM power amplifiers operate using Class C final stages.  Those are typically about 35%-45% efficient.  So if the RF power output is set to 10W output the radio will be dissipating about 25W in heat.  Let’s assume the mentioned radio is a Yaesu FT7800R.  Per the specifications, current draw is as follows: TX=8.5A, RX=0.5A at 13.8V.  So lets do the math.  If the radio is transmitting at 50W RF, the transmitter will draw 8.5-0.5 = 8A.  At 13.8V that’s 110W, which means that 60W must be dissipated in heat!  You know where the power amplifier resides in a transmitter?  Right next to the antenna connector!  Do you think 60W won’t heat up the radio and the antenna connector? Thing again!

Second, the comment about RF power reflecting, heating up the radio and damaging it is plain wrong.  Power amplifiers are not resistive – they don’t dissipate much power.  Their reverse impedance is NOT 50Ohm.  Reflected power from a non-resonant antenna comes into the radio and gets re-reflected back into the antenna where some or most of it will be radiated.  The only thing that can damage a radio is excessive voltage which causes component breakdown.  The excessive voltage is a result of a inductive (i.e. non resonant antenna).  It is important to understand that the power amplifier fails not because of heat dissipation – but due to voltage breakdown.

It’s time hams stop perpetuating false information!

The Shenzhen Mastech HY3003-3 DC power supply is a linear triple output power supply with two adjustable 30V/3A outputs and one fixed 5V/3A output.  It has an LED panel meter for each supply for voltage and current readout.  Not surprising the calibration wasn’t perfect.  So In an unrelated attempt to repair the 5V banana jacks, I decided to figure out how to calibrate it.  It turns out it’s not too difficult.

WARNING – PROCEED AT YOUR OWN RISK. I am in no way liable for you hurting yourself or damaging your equipment.

Here is the procedure:

1) Remove the six sheet metal cover screws, three from each side and remove the top cover.

2) Power on the power supply and give it a few minutes to stabilize (thermally).

3) The LED seven segment displays are mounted on a green FR4 PCB with two WS7107CPL DMM chips – one for each supply.

4) Locate trimmer W1, it is located immediately adjacent to the WS7107.  Using a millivolt DMM, set the voltage across pin 36 with respect to pin 35 to 100mV.  Mine was 105mV prior to adjustment.

5) Set the power supply to maximum voltage – around 34V and plug a DMM into the output banana jacks.  Now, locate trimmer W2 and adjust it so the panel meter agrees with the DMM.

6) Repeat for the second power supply and your done!

Since the sad events that transpired on Feb 26, 2012 and ended with the killing of Trayvon Martin by George Zimmerman the Brady campaign has been out in full force to denounce this “NRA style gun violence”.  The interesting part of this is that the Brady Campaign has tried and convicted – THE VICTIM.

At this point, Police reports and 3rd party evidence clearly demonstrate that Trayvon Martin attacked George Zimmerman, broke his nose, dropped him to the ground and was bashing his head into the ground.  As a result, George Zimmerman acted in self defense, shot and killed Trayvon Martin.  We will probably never know the exact circumstances that proceeded that, and it is clear that neither parties were making good decisions, but it is also clear that Trayvon Martin was the aggressor and George Zimmerman was the victim.

So it is only interesting that the Brady Campaign, an extremist organization that claims to be a strong proponent of constitutional rights including the right for self defense have already tried Zimmerman and found him guilty of self defense with a firearm.

Dan Gross writes “This is how the NRA wants it.  Guns in the hands of just about anybody, just about anywhere.  That’s their vision.”.  Dan, you are wrong, this isn’t how the NRA want’s it, it is how the American people want it for self defense is a right no person has the right to take away from another person.

Sara Brady writes ” If George Zimmerman had not had a gun with him, Travon Martin would still be alive today.” Indeed, Trayvon Martin may have been alive today, but based on THE EVIDENCE, there is an excellent chance that George Zimmerman would have been dead.

Of course, when it is ok to be victimized and killed per the Brady Campaign.  Aggressors have a g-d given right to be protected against a victim defending themselves?  How dare a victim turn the tables on their aggressor?

Sure enough, the Brady loonies show their real colors once again…

More about the Brady Campaigns lies can be read on this page.

As of July 1st 2011 all California homes must have Carbon Monoxide detectors installed when a home is built or when it is sold.  I thought this was an odd requirement for a fair weather state.  The CDC claims 400 people die every year in the USA of Carbon Monoxide poisoning.   The State of California accounts for 11% of the population of the US, so if we pro-rate with all other things being equal, that would amount to 47 victims in California every year.  The LA Times claims that up to 40 people die each year in California from Carbon Monoxide poisoning (but they fail to provide a credible reference to that statement.)  Regardless, it demonstrates my extrapolated number roughly agrees with their claim.  There are about 11 million homes in the state, and an average Carbon Monoxide detector costs $25 and lasts 5 years.  So this means that we have just created a  $55 million dollar per year revenue stream for Kidde and the likes for the foreseeable future.  This also means that we the tax payers need to shell out $1.375 million dollar per victim.

Now, Kidde and other interested groups tell us about the dangers of Carbon Monoxide poisoning but they forget to tell us that Carbon Monoxide poisoning is common in cold states where people operate gas fueled heaters in a closed home.  This is not common in the State of California.  Also they claim that Carbon Monoxide poisoning can happen from a malfunctioning gas burning appliance like a furnace but the overwhelming number of accidents is from someone stupidly operating a gas generator inside a home for power and heating.

So in reality, Carbon Monoxide related deaths due to malfunctions is insignificant and we have to ask ourselves why California State Senator Alan Lowenthal (D-Long Beach) pushed this bill through.  I wonder how much Kidde contributed to his campaign… This bill doesn’t make sense for California.

In the market for a sewing machine?  Think that it’s a competitive consumer market? WRONG!

Low end sewing machines can be purchased at your local discount store (Walmart/Target/Sears/etc.), but if you are looking for anything better, you’ll have to go to a local sewing machine store where you will meet your local franchise owner of brands like Brother/Bernina/Elna/Singer.  If you call around sewing stores to price shop, you’ll discover that the dealers will make statements such as:

1) “We’re not allowed to provide prices over the phone”  and they will tell you they can lose their license if they provide the price over the phone.  The only thing they will provide over the phone is the list price which is absurd.

2) “We don’t service machines that weren’t purchased here”.

3) “We don’t service machines that weren’t purchased through an authorized dealer”.

When you come to the store, you’ll hear about the “great sale” they are having and they will make sure they point out the list price.  Well, their sales never end, and the list prices are unrealistic.  In reality, the machine manufacturers have established sales territories where dealers have exclusivity and the franchising agreements are set up to protect those territories.  When we purchased our first sewing machine we got bitten.

Recently, we purchases a serger.  Once again no one would provide prices over the phone.  Everyone wanted us to come in since “hands on the wheel are sure to close a deal”.  Since we realized that sewing machines are sold like cars, we decided to purchase it like if we were purchasing a car.

Outcome?  We walked out with a brand new ELNA-745 serger for $575 out the door, list price $1,799 – LOL to that!

So, if you are in the market for a sewing machine, find the machine you like, and then haggle haggle haggle!  The dealers are scum balls and use the same tactics as used car salesmen.  They will force you into their store for a price, they try to convince you that if you don’t buy from them you won’t be able to service your machine, they will dazzle you with a “sale” price and make sure they show you the sticker list price to try to convince you that you are getting a good deal.  So don’t forget that you can easily bring the price down another 15% if you haggle a bit.

Recently I heard of an initiative to create a federal committee that aims to set the profit margins of gasoline producers due to what some call “excessive profits”.   Apparently, this “independent” and “just” committee will determine a “fair” profit that the gasoline producers will be allowed to keep.

That got me wondering just how much the State and Federal governments profit from gasoline sales and whether those were “fair” or “excessive” profits.

So when I stopped to gas up, I took a photo of the breakdown of taxes (included at the bottom) and did the following calculations:

Looking at the data, it comes as a bit of a surprise that 27.6% of the price we pay at the pump is taxes!  I am not sure I know of any other product on the market that is so heavily taxed by the government!  Of that, the State of California makes a whopping 20.7%.

So, if this committee ever becomes reality (probably won’t) I propose we create an equivalent citizen’s committee that will determine what a “fair” government tax is on gas

Picture taken at the gas station detailing the various State and Federal taxes:

We recently purchased a new toaster oven.  What’s so exciting about that?  This one has a 5 position cooking mode – with just two heating elements: top and bottom.  So what’s the difference between the modes?  Here is what 20 20 minute test yielded:

1) WARM: Top elements only.  Power consumption = 363W.

2) BROIL: Top elements only. Power consumption = 681W.

3) BAKE: Top element low, bottom element high.  Power consumption = 1012W.

4) TOAST: Top element high, bottom element low.  Power consumption = 1315W (?!?!?).

5) GRILL: Both elements high.  Power consumption = 1300W.

What I think is going on is that the controller does PWM (Pulse Width Modulation) in 0%, 50%, 100% steps.  If the steps are normalized, the each step is about 325W.  So one set of elements at 50% consume 325W (WARM), one set of elements at 100% power is 650W (BROIL).  One set at 50% and the other at 100% power consume 975W (BAKE) and all elements at full power consume 1300W.  That doesn’t match my observation that in TOAST mode it consumed 1315W.  So the toaster oven has an “enigma” mode in which it consumes 325W more than expected.

And did you ever wonder what a “pizza bump” is?  All it means is that the back of the toaster oven has a circular outward bump so that you can put a 12″ inside the not so rectangular oven.  Typically, this also means that you got one wire rack with a circular back to match.

Now you know as much as I do about toaster ovens!

So, it’s been about a month since I have put together my own DVR expander using a Samsung 750GB SATA hard drive an an old USB enclosure.  In the past few weeks, the DVR started developing an allergy to the external drive.  It would manifest itself in random reboots and more recently the symptoms have gotten worst.  When we tried to play shows that were saved on the external drive, the DVR reported that the show was recorded on an external device that is not accessible.  At the same time, the DVR still reported the full expanded capacity of the DVR and external drive.

At first, this was resolved by a simple reboot, but lately it hasn’t been working.  It’s now to the point that we can’t watch any show that was recorded on the external drive.

Cox, can you get any firmware right?

During the month of September Cox Communications announced to it’s customers that it is enacting monthly date caps on its cable Internet customers.  Our cap is 50GByte per month.  Just today (November 2nd) I received another email to let me know that Cox is discontinuing it’s WebSpace service.  WebSpace is a home page service that Cox provided in lieu of letting people run their own web servers at home.  Cox blocks ports 80 and 443 (amongst others) which prevents people from operating a home web page on an address without an explicit port redirect.  Obviously, Cox hasn’t decided to reverse it’s policy to block ports 80 and 443.  This has been a long and slow process by cox to reduce its service level while raising prices.

Cox, you suck!

Last year I purchased a three pack of WaterSentinel WSL-1 water filter.  WaterSentinel claim it’s a direct replacement to the LG 5231JA2002A refrigerator filter.  I put the first one in, and within 10 minutes I had a flooded refrigerator – what a bummer!  Not even their “Free Silicone Lubricant” helped.  I ended up having to pull the O-rings off the original filter and put them on the WSL-1.  Unfortunately, this happened with all three WaterSentinel filters.  I tried to email customer service about this in early September but I never heard back.  I think I am going to try a different brand of water filter next.