Mohican question, capacitors.

[Paul Berger (Canada)]

(01-20-2016 11:41 PM)Geoff Quickfall Wrote:  I just picked up an HP 1202a and a newer Hameg 203-7. The Hameg is 60 MHz and I have 4 new 100mHz probes.

I cannot see why the 100mHz probes cannot be used on the Hameg. The 100 look more capable with higher tolerances for voltage. Is that true or will they distort the results.

You are right 100MHz probes should not be a problem on a 60MHz scope one of the issues you may encounter is the probes need to be matched to the input impedance of the scope. Most scopes have a 1 megohm input impedance but there are exceptions. Most probes also have a trimmer capacitor in them to reduce distortion.

Quote:Geoff

On another note, I need a 6 inch oval 34ohm speaker for an Heathkit Mohican short wave. Will a lower homage speaker with an inline resistor in series and totalling 34 ohms work. Keep in mind this is a low wattage receiver and heat generation by the resistor would not be great.

I know it is the coil that should be 34 ohms.

Putting in a series resistor would protect the output transistors from overload, but I would expect less volume and likely some distortion. For instance if you used an 8 ohm speaker and a 26 ohm resistor more than 3/4 of the output voltage will be dropped in the series resistor. The rating on a speaker is not straight DC resistance it is AC impedance at a specific frequency.

Paul.