Re: DC508A Frequency Range


Hi Gary,
The DC508A and every frequency counter works down to almost DC limited by the duration of the period between measurements. A 1sec measurement period can measure to 1Hz. A 10 sec period can measure down to 0.1Hz. And so on. There is no lower limit. Without a long enough period you won't get any resolution unless you have a reciprocating counter.
For HF you will almost always use 50 ohm impedance. For low frequency work 1Mohm is more typical.

The manual clearly states the resolution enhancement circuitry only works between a certain audio frequency range. I don't recall the range off the top of my head. The answer is DEFINITELY in the service manual.

Dennis Tillman W7pF

-----Original Message-----
From: [] On Behalf Of Gary Robert Bosworth
Sent: Saturday, February 15, 2020 6:02 PM
To: TekScopes@groups io <>
Subject: Re: [TekScopes] DC508A Frequency Range

Thank you Bruce. I already had the Operator's and Service Manuals. The specifications state that the 508A will work from 100MHz to 1.3GHz but does not state exactly how low it will work. It appears that there is a high-pass filter that passes frequencies above 100MHz, but I was hoping someone knows if the counter will readout at 50MHz without the error LED coming on. It is not made crystal clear. I have been coping with specsmanship since 1964.


On Sat, Feb 15, 2020 at 2:47 PM Bruce Atwood <atwood.1@...> wrote:

See page 1-1.

Gary Robert Bosworth
Tel: 310-317-2247

Dennis Tillman W7PF
TekScopes Moderator

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