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   Home   Help Search  
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 41 
 on: Today at 11:37:41 AM 
Started by KB2FCV - Last post by W8JX

The point DID NOT go over my head and I will stand by my answer.  The suggestion to call the 800 number is SPOT ON!  If NO ONE takes the manufacturers to task, they will continue to produce more inferior products and our problems will grow!  We can't solve all the problems they create.


No it did go over your head completely. A typical CB/HAM answer, you want to pass the buck. Stop skating around it. If you cause a problem for your neighbor you should help fix it and not be a arse about it. If your neighbor spiked your coax his problems would go away. You are cause not him or device maker because it is possible to overwhelm any device with RF if its strong enough and I have yet to see in a manual that this new TV or audio is certified to work next door to someone running 1500 watts or more with no regard for you.

 42 
 on: Today at 11:36:28 AM 
Started by VE1FAL - Last post by W4KYR
As the subject says, I am looking for a copy of ROC Digital Desktop.  I want to use my old PK232 in host mode.  All the old software seems to be non-existent on the net these days.  There are many options for running the 232 in command mode but that is not what I am looking for.

So if you have an old copy of ROC that you are willing to part with please let me know.

Thanks,
Doug

I am looking for ROC as well

 43 
 on: Today at 11:31:13 AM 
Started by KK7GB - Last post by KK7GB
I need the connecting cable from a TS-130 to an AT-250 tuner. Unfortunately, due to physical limitations, I am unable to build one. If someone would undertake this project for me, I would gladly pay.

Thank you

Glenn KK7GB

 44 
 on: Today at 11:27:33 AM 
Started by K0XY - Last post by W8JX

My guess is that #18 or larger will survive, especially assuming that you aren't running 100%
duty cycle.  But if you have any concerns, #12 should be more than adequate.  


18 ga multi-strand will work and anything over 16 is not needed. I would use soft drawn pure copper if this is a collapsible antenna. Heavier wire is unneeded and it will not fold-up/collapse as well. When some use larger wire for large dipoles and such it is for more strength in winds and icing not because it is needed electrically.

Also I might add that you do not use house wiring amperage ratings for single wire runs as they can handle a lot more current. 20 amps on 16 ga in a single run is not a big deal. Many would be afraid to use their car if they know how small the wiring sizes are in it vs house wiring standards.

 45 
 on: Today at 11:25:36 AM 
Started by K0XY - Last post by W9IQ
You didn't mention what type of ground system or the intended frequency range.

31 feet of 14 ga copper wire (solid) has an RF resistance of 2.5 ohms at 28 MHz. If you assume a radiation resistance of about 36 ohms, your efficiency will be 94% - not counting the losses in your ground system.

- Glenn W9IQ



 46 
 on: Today at 11:20:04 AM 
Started by VE3TMT - Last post by VE3TMT
I need to confirm a 40m SSB contact. Can't find their email on the website, other than dxfriends@dxfriends.com

Anyone confirm the email address to verify a contact?

Thanks,
Max

 47 
 on: Today at 11:16:44 AM 
Started by K0XY - Last post by KM1H
IOW #14-16 is a fine compromise Wink

 48 
 on: Today at 11:14:40 AM 
Started by KT0DD - Last post by KM1H
Quote from:  link=topic=82569.msg987602#msg987602 date=1490283790
I know very well what's going to happen but......my original Eimac 3-500Zs are well over 34 years old and still putting out 1200W !  Thank you Eimac!

Perhaps the Eimac aluminum air sockets are partly responsible for this longevity?

If anything Id say it was in spite of those sockets that are well known for their air restriction. A suitable noisy blower is needed to do the job well; if you have ever listened to a BCB station that uses 4-400A's or 5-500's you know what I mean.  I use an all metal EBM-Papst fan to cool mine in the standard Johnson ceramic socket. In a serious contest or on AM I use a 2 step fan speed otherwise just the normal slightly slower which is barely audible.

 49 
 on: Today at 11:14:37 AM 
Started by KN1W - Last post by N8CBX
...The three Eimac spec sheets listed below show the minimum voltage on the anode to be 3000 volts...
Seriously, I think you need your eyes checked.
Jan N8CBX

 50 
 on: Today at 11:13:25 AM 
Started by K0XY - Last post by WB6BYU
If you are using the antenna as a quarter wave on 40m, the feedpoint impedance is likely in the
range of 20 - 30 ohms (or more, depending on ground loss resistance.)  Using 20 ohms as a
conservative number,  we can calculate the square root of ( 1500 / 20 ) = 8.7 amps RMS.
That's probably worst case (assuming you aren't trying to work any bands below 40m.)

Then the question is, what size wire will carry 8.7A?

This wire table shows the recommended
maximum currents for chassis wiring and for "power transmission".  So, depending in which set
you think should apply, the answer is either #12 or #21.  This doesn't include a correction
for the increase in resistance at RF due to skin depth, however.

My guess is that #18 or larger will survive, especially assuming that you aren't running 100%
duty cycle.  But if you have any concerns, #12 should be more than adequate. 

Using a fatter conductor (or multiple strands to simulate one) will reduce the voltage at the
tip of the antenna.

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