Topics

HF9V


Brent WB4X
 


-- Finally recieved my capacitors that I ordered off ebay. It took 45 days to get here. Now I can get back to the HF9V-x rebuild.
 
Charles  WB4X


Mark Brueggemann
 

If you're not running a kilowatt you don't need RG-11 for the matching section.  RG-6 TV coax will work just fine provided you've got crimp connectors for it, or it's got copper braid you can solder.

Mark K5LXP
Albuquerque, NM


 

Mark,
This is a statement that has been making it around for years.  I wish people would not keep making the statement that RG-6 is OK to use.  There are so many variations in the manufacture of RG-6 that a blanket statement is going to result in damaged equipment or worse.  Even when I bought RG-6 in bulk for the TV station I worked for, using the same part number from the same distributor and manufacturer, the product I received changed often.
--
Al
WB9UVJ


Mark Brueggemann
 

This isn't a CATV system where an out of spec line can make a difference at hundreds of MHz.  I would offer just about anything will work just fine as a quarter wave line at 14MHz.  Use what is now a ubiquitous analyzer to cut a section with any arbitrary vf to length, put connectors on it and check the box.  You would be hard pressed to measure any difference much less dire as damaging failure.  But that's just my opinion, since I've had an RG-6 section on my current HF6V since about 2005.  Seemed silly at the time to order RG-11 at a buck a foot or whatever plus shipping when I have hundreds of feet of RG-6 on a roll sitting around.  Since I've been @100W or less since I was licensed I'm guessing the RG-6 will continue to be OK.

Mark K5LXP
Albuquerque, NM


Andrew KD5RKO
 

Thanks Mark, I plan to do just that with my HF6V! I have a nanovna to measure with so I'm good there.
Now I just need to figure out the proper procedure for testing it using my nanovna.

Andrew - KD5RKO

On Fri, Aug 21, 2020 at 9:20 AM Mark Brueggemann via groups.io <qrq_cw=yahoo.com@groups.io> wrote:
This isn't a CATV system where an out of spec line can make a difference at hundreds of MHz.  I would offer just about anything will work just fine as a quarter wave line at 14MHz.  Use what is now a ubiquitous analyzer to cut a section with any arbitrary vf to length, put connectors on it and check the box.  You would be hard pressed to measure any difference much less dire as damaging failure.  But that's just my opinion, since I've had an RG-6 section on my current HF6V since about 2005.  Seemed silly at the time to order RG-11 at a buck a foot or whatever plus shipping when I have hundreds of feet of RG-6 on a roll sitting around.  Since I've been @100W or less since I was licensed I'm guessing the RG-6 will continue to be OK.

Mark K5LXP
Albuquerque, NM




--
Andrew - KD5RKO


 

Mark et al,
You are missing my point.  When someone makes a blanket statement about RG-6 some of the readers do not know the types of product that are out there.  I am not talking about frequency response,  I am talking about cable that is not designed for anything greater than a few watts.  I am talking about cable that has a tendency for center conductor migration that will cause potential shorts.  I am talking about shields that for the most part are thin aluminum foil.  I am talking about foam insulation that breaks down with temperature, wicks moisture into the line and a cable that might not be tolerant of high voltage spikes.  I am talking about plating on the steel center conductor that is microscopic compared to other types of cable.  I am talking about using one of these substandard cables with an antenna that suddenly failed, (like an HF6V where the top section has slid down inside the net section) and the voltage on the line rises to several hundred volts due to the mismatch.
Of course, in an emergency I might use RG-6.  I might even use an RG-6 that I knew had good manufacture and I knew the specs for breakdown, center conductor, shield and dielectric, etc., if I could not obtain RG-11.  I cannot in good conscience recommend just any RG-6 for this application or any that had anything but QRP power.  I can see the benefit of using RG-6 for receive antennas or for temporary installations.  However, when you compare the cost of using a known good cable compared to the cost of station equipment and safety, I think you have to agree other cables are indicated.
--
Al
WB9UVJ