[TowerTalk] Ferrite beads for LDF4-50?

[Richard (Rick) Karlquist]

It is important to distinguish between the two types of connector "loss":

1.  Dissipation loss, which would cause connector heating.

2.  So called mismatch "loss" IE reflected power.

For #1, I would suggest running 1,500W through the connector in question 
for a while and seeing if there is any significant heating.

For #2, terminate the cable with connectors in an ACCURATE 50 ohm 
termination and measure the VSWR with a calibrated VNA.

Below 200 MHz, I would venture to say that loss of either type should be 
virtually unmeasurable.  The tests above are more of the "sanity check" 
type to detect improperly installed connectors, or offshore connectors
that are complete junk, or connectors that got water inside.  Even if 
some mismatch is detected (like 1.1 to 1) it likely doesn't matter for 
ham radio.

Rick N6RK

On 8/23/2025 12:19 PM, Jim Brown wrote:
> On 8/23/2025 11:08 AM, john at kk9a.com wrote:
>> I mostly agree.  Connector loss is minimal.
> 
> Yes. About 15 years ago, I made up a lot of cables for a DXpedition, 
> with soldered 83-1SP on 100 ft lengths of Commscope 3227, an RG8-size 
> cable with a solid #10 copper center and foil/tinned copper braid that 
> is superior to LMR400. For final test, I spliced all 13 of these cables 
> together and measured loss by substitution using HP generator and 
> spectrum analyzer. That's 12 barrels and 26 83-1SPs.
> 
> Loss at 200 MHz (as high as I went) was slightly less than the mfr's 
> spec for the cable.
> 
> 73, Jim K9YC
> 
> 
> 
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