Dip Meter basics... - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: July 06, 2012, 06:13:39 pm
content: Ever wonder what a Dip Meter was?Other variants are the Grid Dip Meter, Grid Dip Oscillator, Tunnel Dipper, etc. Lots of names an variants of the same concept - a tunable oscillator with an exposed coil that can be coupled to circuits/devices under test to determine resonant frequency, as well as circuit operating frequency (in most varieties).I put together a short video to illustrate...

author: Rick
author_rank: Frequent Contributor
timestamp: July 06, 2012, 06:43:01 pm
content: We can do the same operation with a signal generator and an oscilloscope connected to the lc circuit right?Those devices are not sold any more; radio amateurs build them themselves.It would be a good idea if "eevblog" or someone else had a project on this topic as those things are not available. It would be very useful.

author: w2aew
author_rank: Super Contributor
timestamp: July 06, 2012, 06:53:44 pm
content: Quote from: Rick on July 06, 2012, 06:43:01 pmNot really, because you are not coupling the actual resonant circuit of the oscillator to your DUT if you use a signal generator. There is at least one Dip Meter that is still being sold new from MFJ (http://www.mfjenterprises.com/Product.php?productid=MFJ-201). There may be others...

author: Rufus
author_rank: Super Contributor
timestamp: July 06, 2012, 07:26:18 pm
content: I have a Trio DM-801.It has a capacitively coupled probe which gives the option of direct connection to the circuit to dip or inject into, also an ear piece and am demodulator.The coils plug into a crystal socket (HC-6?) with a smaller socket (HC-49?) next to it. You can plug crystals into either and use it as a crystal oscillator to test them that gives you a crystal controlled signal source too.A used one recently sold on ebay for GBP 140 - ouch - good pictures in the listinghttp://www.ebay.co.uk/itm/Trio-Kenwood-Dip-Meter-DM-801-/370625734004?pt=UK_Mobile_Phones_Communication_Radio_Meters&hash=item564b03e574

author: w2aew
author_rank: Super Contributor
timestamp: July 06, 2012, 07:43:35 pm
content: Quote from: Rufus on July 06, 2012, 07:26:18 pmThat's a real nice unit - too bad they don't make it anymore. I've seen a few for sale, but they've all been a bit pricey.

author: Rick
author_rank: Frequent Contributor
timestamp: July 06, 2012, 07:46:46 pm
content: Quote from: w2aew on July 06, 2012, 06:53:44 pmWe are not coupling but we are feeding a signal with a given frequency to, say an LC circuit and observing the amplitude response of the LC circuit by varying the frequency of the signal. Isn't that enough to determine the resonance frequency of an LC circuit?Thanks for the link. I wonder why they do not use digital displays in those devices...Oh you mean that some other components in the signal generator will affect the LC circuit's resonance frequency...

author: w2aew
author_rank: Super Contributor
timestamp: July 06, 2012, 08:00:41 pm
content: Quote from: Rick on July 06, 2012, 07:46:46 pmThis will work provided the scope connection (probe, etc.) doesn't alter the resonant frequency of what you're measuring. This will work fine for LC circuits, but not necessarily so well for things like direct measurements on antenna elements, etc.

author: G7PSK
author_rank: Super Contributor
timestamp: July 07, 2012, 02:38:01 pm
content: Before they had dip meters they used a neon lamp, switched range on capacitors and a variable inductance called a variometer.Also once saw a method demonstrated that used a long plank two wire and a light bulb to find the wave length from which to calculate the frequency hard to get simpler than that.