DER EE DE-5000 LCR Meter


Staff member
May 15, 2011
Sterling, MA
Old 'Arn Enthusiast
I had a nice looking one my dad and I (mostly him) made. We added balsa slabs to the sides to create wheel wells and sculpted wood putty to smooth alll the right curves… had a C3 type rear window; long nose short tail which was angle cut like the early road racers. Drilled holes in the back for exhaust.

Painted a dark red and black windows painted on. Pretty cool but it wasn’t a winner on the track or in the show.
It takes a lot of physics to make a winning car


Veteran and General Yakker
Aug 13, 2014
So I am not clear on 50 ohm vs 75 ohm vs 93 ohm but do understance the difference in induction in coax cables. Please comment

here is some comparison

RG6QS loss 4.77db/100ft @ 550MHz 75 ohm cable 20pf per foot

RG174 loss 17.3dB/100ft @ 400MHz 50 ohm cable. 31pf per foot

RG62u loss 4.9db/100ft @ 500mhz. 93 ohm cable. 13.5pf per foot

here is comparison table


Veteran and General Yakker
Jun 24, 2011
Jacksonville, FL
So I am not clear on 50 ohm vs 75 ohm vs 93 ohm but do understand the difference in induction in coax cables. Please comment
For high voltage, the perfect impedance is 60 ohms. For high power, the perfect impedance is 30 ohms. For low loss, the perfect impedance is 75 ohms.
This means, clearly, that there is NO perfect impedance to do everything. What we ended up with was a compromise number, and that number was 50 ohms.

(4 MHz graph shown, the effects are less at audio frequencies at or below 20KHz)

You will note that 50 ohms is closer to 60 than it is to 30, and that is because voltage is the factor that will kill your cable. Just ask any transmitter engineer. They talk about VSWR, voltage standing wave ratio, all the time. If their coax blows up, it is voltage that is the culprit.
So why not 60 ohms? Just look at the power handling at 60 ohms - below 50%. It is horrible! At the compromise value of 50 ohms, the power has improved a little. So 50 ohm cables are intended to be used to carry power and voltage, like the output of a transmitter. If you have a small signal, like video, or receive antenna signals, the graph above shows that the lowest loss or attenuation is 75 ohms.