Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 2 3 [4] 5 6 7 8 9 10 Next
 31 
 on: Today at 05:40:00 PM 
Started by ONAIR - Last post by ONAIR
Looks like an opening tonight as well!

 32 
 on: Today at 05:37:43 PM 
Started by K1PJR - Last post by W9IQ
Quote
I ended up removing the baluns except where I was sure they are not having any negative effect on SWR - Steve JS6TMW

Steve,

If the balun has a "negative effect on SWR" (SWR goes up) and if the coax/ferrite choking balun is properly constructed, then this is a good indicator that you do have common mode current present. By inserting the choking balun, you are altering the impedance of the antenna and thus the SWR since the feedline can no longer participate as part of the radiating/receiving antenna.

- Glenn W9IQ

 33 
 on: Today at 05:32:05 PM 
Started by N1GDO - Last post by ROB1955
Purchased an Alpha Coax Loop because of apartment restrictions.
I have only used it indoors.

Watch the following video and it's probably going to help you to understand why you've so much problem with your Alpha Coax Loop:

https://youtu.be/DR-VBopiZL4

- Rob

 34 
 on: Today at 05:29:52 PM 
Started by WY7CHY - Last post by VK3BL
You are correct. The dissipation will be approximately the same. Approximately. However, there will be a lower amount of current, mainly grid current. That does have a positive affect when lower. E.g. Whether the tubes put out 600 watts and dissipates 270 watts, or they put out 500 watts and dissipate 250 watts, or they put out 700 watts and dissipate 280 watts, there is a difference on the tubes, or solid state drives.

Tom W8JI argues that Thoriated Tungsten filaments don't care whether they are being run gently, maxed out, or even idling, they will deplete at the same rate.

What are your thoughts on that?

I'm not saying loafing is bad, or that you shouldn't run at less than full throttle... its just that there seems to be a lot of belief out there that doing so will save tubes... having also done the math, you can also see that there is no strong basis for that belief.

The best way to save tubes in an AL-811 or AL-572 is in my experience to turn the amp off when you're not using it, or going to use it in the next 30 minutes.  I've depleted emission on plenty of filaments, but I have never once snapped one from thermal shock. 

In fact, the death knell for the 572B that failed recently on me was when I took an unexpected nap and the amp stayed idle for 8 hours...  Next time I used the amp, that tube was 50% down on emission.

 35 
 on: Today at 05:27:31 PM 
Started by WX4SNO - Last post by ROB1955
I use an Alpha EzMilitary with my 817ND and love the antenna. Great company and very well built.

What? Great company and very well built!??! I guess that you never watched the following videos:

https://youtu.be/HlmirEALEdQ

https://youtu.be/4n30XykCChY

https://youtu.be/XXLVDTHz9GY

- Rob

 36 
 on: Today at 05:26:35 PM 
Started by VE3NEA - Last post by AE5X
When we listen to weak signals in the noise, sometimes we "hear" our callsign even if it was not sent. Here is why:

Interesting video and maybe explains a "not in log".

 37 
 on: Today at 05:20:59 PM 
Started by KJ6TSX - Last post by W9IQ
George,

Here are some possibilities to check out:

1.) Tuning the dipole inside can cause it to be coupled to other things in the room and house. This will throw off the tuning compared to tuning it in the "open field".

2.) You mentioned a 1:1 SWR yet an impedance of 57 ohms. If you did this measurement at the end of your 31" coax, then you are not measuring the impedance of the antenna although the SWR should be relatively accurate. I bring this up since your 18" antenna lengths seem short for a 1:1 SWR. I would have expected something closer to 19.25".

3.) I agree with Don's observation regarding your 1.7 dB loss for the short length of coax. If this loss is really present and you tuned the antenna by measuring the SWR at the end of this cable, then your antenna is not properly adjusted. The coax needs to be fixed or replaced and then you need to repeat your tuning of the antenna.

4.) You added the 10 feet of RG 316 in the field. This should introduce a loss of about 1 dB. But since you did not have this in your original tested configuration, you should check for a bad 316 cable and associated connectors and unions. Bent or short/broken pins are a common problem. Make sure to resistance test all cables while moderately flexing them to help reveal any intermittent connections. Crushed cables can also introduce substantial losses.

5.) You didn't mention how you supported the antenna when in the field but if you were holding it, for example, this could seriously degrade performance.

I hope that helps.

- Glenn W9IQ

 38 
 on: Today at 05:20:29 PM 
Started by KA4NMA - Last post by ROB1955
Does anybody know what is in the block box on this antenna?  Balun? How could I hombrew one? 

Randy

You'll find the answer to your question after watching the following video:

https://youtu.be/HlmirEALEdQ

- Rob

 39 
 on: Today at 05:13:52 PM 
Started by WY7CHY - Last post by WY7CHY
You are correct. The dissipation will be approximately the same. Approximately. However, there will be a lower amount of current, mainly grid current. That does have a positive affect when lower. E.g. Whether the tubes put out 600 watts and dissipates 270 watts, or they put out 500 watts and dissipate 250 watts, or they put out 700 watts and dissipate 280 watts, there is a difference on the tubes, or solid state drives.

And yes, there is a point whereby loafing too much can be a negative. But a reduction of 15% is not going to cause a negative. There's a lot more to a drive, tube or solid state, than just its dissipation. If not, then as long as the tubes were dissipating no more than 65 watts +/-, you should be able to drive it with 200 watts.

But to answer your question. When putting out 500 watts, I am only drawing approximately 500ma. That means a total of 725 watts. Which means the tubes are only dissipating approximately 56 watts each. So yes, there is a difference.

 40 
 on: Today at 05:09:06 PM 
Started by KD4QFT - Last post by K7FF
N9LCD

Just because a seller has been around the block a number of times DOES NOT MEAN that he can be trusted.

1.  The sales may be completely bogus and feedback posted using hacked passwords.

2.  Fake sales may be "MADE" to "ACCOMPLICES" who automatically leave positive feedback.

3.  In the classic PONZI scheme, the first ones are the ones who get out intact.

4.  The sales may be valid but they may be what's known in retailing as "LOSS LEADERS".  In other words, the scammer
     unloads a bunch of gear at a loss to get "GOOD" feedback and then turns around a pulls off a massive scam.

Hinky is as hinky does.

A bit of fanciful conjecture, or perhaps you speak from personal experience?

How about an example or two where you can can establish and prove that such nefarious activity has actually occurred on the Classifieds, at least during our lifetime?  
 
Or, is this just another example of the currently widely popular bogus conspiracy theories that the public, including some here on eHam, buy into and accept without support or proof just because they want or have a need to believe, or which support their evil purposes...?

You know, paranoia and intentional misinformation are destructive and terrible to behold.

Derek
K7FF

Pages: Prev 1 2 3 [4] 5 6 7 8 9 10 Next
Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!