HF, VHF, UHF, and Grounding

[spanky15805]

Blown PolyPhaser.

 

[prcguy]

Blown PolyPhaser.

View attachment 72478

Are you sure that's a Polyphaser? Are you sure its blown? That looks like a gas tube and I don't think Polyphaser uses gas tubes. The brown mark looks like solder flux from when it was soldered in.

 

[westom1]

Gas Discharge Tubes (GDTs) are necessary for low capacitance required by radio frequencies and other communication lines.

 

[prcguy]

Original Polyphaser products didn't use gas discharge tubes and their advertising compared the benefits of their design to inferior gas discharge tube types and the fact theirs can take multiple hits and gas discharge tubes cannot. Later on Polyphaser started using them in DC and control line products and some antenna lightning protectors. Gas discharge tubes aren't necessary, they are just one of many methods of lightning protection.

Gas Discharge Tubes (GDTs) are necessary for low capacitance required by radio frequencies and other communication lines.

 

[spanky15805]

100% sure it's a PolyPhaser.

 

[westom1]

Gas discharge tubes aren't necessary, they are just one of many methods of lightning protection.

GDTs may die on first use or will survive many transients. Depends on something always necessary to have an effective solution: specification numbers.

Plenty other technologies exist. Low capacitance required by telcos once used 'carbons'. Those protectors were upgraded by a semiconductor technology also with sufficient low capacitance.

But when the signal is high frequency, of the many possible technologies, GDTs are a preferred choice. And so that point. GDT would be a best protector (for many transients) due to low capacitance.

Obviously AC line protectors do not need low capacitance. So another technology is used.

Only item always required to make every protector (all technologies) effective is what that protector connects to and the impedance of that earthing connection.

 

[doctordialtone]

Low capacitance required by telcos once used 'carbons'.

True.
Up until the 70's Carbon Protectors did the job. See the side of your house. In the 80's with the advent of Electronic PBX's, Gas Tube Protectors were the only semi-reliable protection from lightning.

 

[westom1]

True.
Gas Tube Protectors were the only semi-reliable protection from lightning.

GDTs were first protectors routinely used even by hams even at the start of the 20th century. What preceded GDTs were spark gaps. Also effective protection with a robust life expectancy. GDTs were simply better than spark gaps. And routinely used on all phone systems.

Carbons (1940s or older technology) then replaced telephone GDTs since a slightly higher capacitance was irrelevant. Since then, 'carbons' were replaced by a semiconductor device (about 1980). It is installed for free on all subscriber (ie home) interfaces.

BTW protectors never do the protection. Effective protectors are only connecting devices to what does all protection - today and over 100 years ago - single point earth ground.

 

[W5lz]

About spark-gap lightning devices.
They are not all that efficient but better than nothing. By the time a charge is strong enough to have bridged that gap, some of that change has already reached what you are trying to protect. 'Part of' or 'not much' at 10k or 30 k volts isn't exactly conducive to electronic 'health'. There is no such thing (for the average person) that is a sure-fire protection from lightning. Still, 'some' protection is better than none.

 

[wcsd45]

Honoring with respect the various points of view here, I found the ARRL book: Grounding and Bonding for the Radio Amateur (Amazon available, get paperback with diagrams) a worthy benchmark explaining different types grounds with useful design/approach advice. Having worked though book, I still had questions. The questions were waaay more informed.

73,

Chuck