[schoolbus]

Hello Hollands,
Those graphs are hard to understand.....if the decibels is a vertical line, why is the graph line (the results) graphed horizontally? I am befuddled.

How is your FF8 going? The results should be interesting, I hope you will post soon.
Schoolbus

 

[ADTech]

The vertical axis is in decibels per the designation of "2 dB/" or "1 dB/" with the implied reference to divisions vertically.

The frequency is plotted on the horizontal axis with the center and the per division (horizontal) listed at the top of the screen.

These readings were done on an early 80s era spectrum analyzer (HP8569B) so there wasn't yet much in the way of computerized processing for the display data.

 

[amcgoody]

Sylvania Pathmaker Balun

I have one model 3002, and the 300,Ohm wire and spade conetector broke off can a new piece of 300 Flat be soldered on ,and how long should it be, also is this a good balun to use? Thank you.

 

[pips]

are u saying the spade broke off your balun?

 

[amcgoody]

Yes and about 1inch of wire broke off, also is that a good one it,s old but not used much.

 

[roger1818]

The spade terminals are usually crimped on. Optimally you want both wires the same length, so you would probably want to trim the other one as well and then crimp new spade terminals on.

Don't really know anything about that particular model. Law of averages says it is probably not that amazing and you could just replace it with another one, but who knows, maybe it is the best balun we have ever seen, or the worst.

 

[amcgoody]

ok it has a cover that screws off and inside is a small circut board with a coil and tansitor the twin lead is solered on to it it is not waterprof, i thougt i make it long enough to try on my GH

 

[stampeder]

Would you be able to post a nice close-up photo of its innards, amcgoody?

 

[amcgoody]

I got pictures posted today (I had HELP) of the balun , Please let me know if it will help me. Thanks They are in album titled GH.

 

[pips]

anyone have a link for a calculator for a 1:1 coaxial cable balun?here is a link with pic of what im talking about.
http://www.iw5edi.com/ham-radio/files/I0QM_BALUN.PDF
after hours of research my google fu is not strong lol.

 

[holl_ands]

The webpage you cited above indicates that Impedance of ALL Coaxes are the SAME, i.e. 75-ohm....and fol. On-Line Wavelength Calculator determines the ELECTRICAL Lengths for a given Frequency:
http://www.onlineconversion.com/frequency_wavelength.htm
The actual Coax Lengths are SHORTER due to reduced speed of light in the Coax, determined by multiplying the ELECTRICAL Length by the Velocity Factor (per cable specs).

The fol. Coax Length On-Line Calculator is intended for the similar (but different) Half-Wave Coax Balun for 300-to-75-ohm (4:1) conversion:
http://www.k7mem.com/Electronic_Not...n+(L) 0'+8-27/32"+(22.5+CM) &Coax_Type_1=On
However, double check the Velocity Factor for YOUR Coax....it could be quite different.

 

[pips]

thank u holl_ands thats what i needed.ill check the v factor of the rg59 im using

 

[holl_ands]

As you might have seen in K7MEM's VF Table, there is a wide variation for RG-59. If built to the MIL-SPEC, the insulation is hard plastic with much lower VF than the RG-59/Foam Insulation which is half-way to RG-6 performance.....and higher susceptibility to mechanical damage and the center conductor melting THRU the insulation when bends are subject to any sort of heat. And there is more than one formula for Foam Insulation, so even RG-6 coax with "Foam" Insulation from the SAME manufacturer can vary....hence the need to check mfr specs....

 

[del32]

antronix BL-75: is this a balun?

Hey all, first post.

I am embarrassed that I know next to nothing about tv/av stuff so I'd like if someone could confirm that a part I have is a balun and not something else.
part no: antronix BL-75

It does work to pull in some signal using a little UHF hoop that is marked as 300 ohm, but the BL-75 only says 75 ohm and nothing about 300 ohm.

I was planning to build an M4 and now that I found this site maybe a GH instead from 12 ga romex laying around, but I want to make sure that part will work for those designs.

Thank you.

 

[Pete Higgins]

Antronix BL-75

The Antronix BL-75 is a CATV Indoor 300 ohm to 75 ohm Transformer. It will work but won't be weather proof.

 

[del32]

Thanks for confirmation.

 

[Flint Ridge]

Would someone be so kind as to point me to the formula for cutting a coax balun? VHF only Ch 8 & 13 is my targets. 13 is the weakest, so I'll shoot for that. Tried the search of this mega thread and did not find what I was looking for. I know it is here, from reading it all a year ago. Seems like the loop was 26". But no guessing allowed.

Thanks all.

 

[BOUVAL]

.
_____________ Coax Balun Calculator

.

 

[Flint Ridge]

Ok, thanks, plus Hollands has a link on the previous page as well.

So, with my Belden RG11 it is Gas-injected FPE - Foam Polyethylene. Therefore I use the velocity factor of .80?

So via Bouval for 1/2 wavelength that is 22.17" and Hollands 1/2 wave link above it is at 22.16"

Looks like spec say..."Nominal Velocity of Propagation: 83 % " So I can tweak that. Hmmm... if I do change via Bouvals - comes in right on 23" now.

Ok, that gives me something to work with. I'll have to work with aluminum instead of copper, but I can work around that.

Thanks!

 

[ProjectSHO89]

If it's Belden's cable, go to their website and look up the data sheet. No guesswork involved.