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Author Topic: First things....  (Read 2878 times)
G3RZP
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Posts: 4962




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« on: July 18, 2012, 11:33:05 AM »

I get the impression that a lot of people who have problems with amplifiers are missing a vital component - a dummy load. I don't mean a dipole on 14313, either.

It seems to me that anyone who buys an amp should get a dummy load and a wattmeter at the same time - if they don't already have them..It would save a lot of hams a lot of heartache when things aren't doing what they expect.

Especially where RFI is, or might be, the problem.

I'm thinking we ought to encourage amp buyers to buy a dummy load at the same time.
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W1QJ
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Posts: 1521




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« Reply #1 on: July 18, 2012, 12:53:29 PM »

I get the impression that a lot of people who have problems with amplifiers are missing a vital component - a dummy load. I don't mean a dipole on 14313, either.

It seems to me that anyone who buys an amp should get a dummy load and a wattmeter at the same time - if they don't already have them..It would save a lot of hams a lot of heartache when things aren't doing what they expect.

Especially where RFI is, or might be, the problem.

I'm thinking we ought to encourage amp buyers to buy a dummy load at the same time.

You are preaching to the choir.  I have been saying this same thing time and time again on here.
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WX7G
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« Reply #2 on: July 18, 2012, 01:38:15 PM »

I don't have a dummy load and have no problem troubleshooting the amp. I tune the antenna for a low VSWR and there's my "dummy load."

Troubleshooting RFI issues? Adjust the power output of the amp and/or transceiver.
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N4CR
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Posts: 1702




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« Reply #3 on: July 18, 2012, 03:14:54 PM »

I use a 50 year old Cantenna with the scope output.

I also have an LP-100A and a Bird 43 but I seldom use them for troubleshooting an amp.

I got the Cantenna at a tailgate for $15 with oil. Checked it with an ohmmeter and it's still an acceptable 51 ohms. Cheap twice the price. I've gotten a lot of mileage out of it.
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73 de N4CR, Phil

Never believe an atom. They make up everything.
AA4PB
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Posts: 13032




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« Reply #4 on: July 18, 2012, 04:49:24 PM »

I don't have a dummy load and have no problem troubleshooting the amp. I tune the antenna for a low VSWR and there's my "dummy load."

And we all appreciate listening to your tuning signals on the air too  Cheesy
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WX7G
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« Reply #5 on: July 18, 2012, 04:58:56 PM »

My amps are solid state and need no tuning.

The antenna is tuned at 5 watts and after being tuned once the screwdriver presets allow it to return to the right spot without transmitting a signal.
« Last Edit: July 18, 2012, 05:00:48 PM by WX7G » Logged
KD0PCJ
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Posts: 20




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« Reply #6 on: July 18, 2012, 05:05:23 PM »

For those with vintage equipment they are indispensable...having one is a given. I would be lost without my $10 ham fest cantenna, or my Drake W-4.  I made the mistake once of trying to tune my amp on 15M for the first time without the dummy load and fried my fragile sweep tube finals in an instant...tough rookie lesson learned.
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G3RZP
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« Reply #7 on: July 19, 2012, 01:47:02 AM »

If something goes wrong, trouble shooting without a dummy load can be real guess work. Is a high SWR because the tx is taking off at some frequency outside the band? Have you suddenly got RF feeedback - maybe a ground lead has broken?

Solid state amps aren't necessarily stable on loads that aren't 50 ohms well away from the band in use, either
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KE3WD
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Posts: 5689




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« Reply #8 on: July 19, 2012, 02:53:03 PM »

For those with amps that require the tuning procedure, dummy load should be part of their lineup for more reasons than just troubleshooting.  For example, the dummy load can be used to tune the amp to a known 50 ohm load before switching to antenna and tuner, thus eliminating the looooong qrm of on-air tuning.   Please. 


73
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AD4U
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Posts: 2186




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« Reply #9 on: July 19, 2012, 03:38:09 PM »

After 45 years in the hobby I am still amazed at the hams who buy an amp and have absolutely NO knowledge of how to tune it or even use it.  I get the feeling that is why so many have problems with Ameritron amps, which seems to have most of the amp market.  They blow them up by mis-use.

Dick  AD4U
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WX7G
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« Reply #10 on: July 19, 2012, 04:03:42 PM »

Try not to picture those the bright orange 811A plates during a long, full power, key down tune.
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KE3WD
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Posts: 5689




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« Reply #11 on: July 19, 2012, 06:50:20 PM »

After 45 years in the hobby I am still amazed at the hams who buy an amp and have absolutely NO knowledge of how to tune it or even use it.  I get the feeling that is why so many have problems with Ameritron amps, which seems to have most of the amp market.  They blow them up by mis-use.

Dick  AD4U

No, no, see, we live in a generation in which everything they do to themselves is obviously the fault of someone else, dontcha know. 

And it is always also a dire conspiracy against them...


73
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K0ZN
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Posts: 1563




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« Reply #12 on: July 19, 2012, 08:29:16 PM »

  Strong second to AD4U's comments.

It is mind boggling to me that many people simply will not pick up a book and study a LITTLE about this TECHNICAL hobby and the related equipment before getting into it.
The cold, hard fact is that Amateur Radio is not "consumer electronics";  success (or avoidance of problems and frustration!) in this game will be very closely related to your level of knowledge...... and this is especially true for antennas and amplifiers.  
  
The FAA requires people to STUDY and take lessons BEFORE they try to fly an airplane!  They have to learn why and how the aircraft works.
I detest excessive government regulation, but sometimes you think maybe something similar to the FAA stance should be in place before someone is turned loose with a high power RF amplifier......shouldn't they have a basic understanding of its theory of operation and the basic parameters of installation, tuning, operation and IMPROPER operation?

73,  K0ZN
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KL3HY
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Posts: 120




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« Reply #13 on: July 20, 2012, 10:35:57 AM »

 Strong second to AD4U's comments.

It is mind boggling to me that many people simply will not pick up a book and study a LITTLE about this TECHNICAL hobby and the related equipment before getting into it.

I'm new to ham radio, only having my license for a couple years now, but coming from an IT (computers and networking) background I'm actually not at all surprised.  IT is also highly technical in nature and it used to astound me how many people claiming to be "system engineers" or some other lofty sounding title are so averse to cracking a book and looking something up.  God forbid they might actually have to read a book in order to learn something completely new. 

It's sad to see this same mindset exists in the ham radio world too, but not all that surprising.  Sad

Mike
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