Grid Dip Oscillators


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Loadstar KDM-6 in excellent condition. Very similar to the MFJ201. Has a frequency range of 1.5-250MHz in 6 ranges, with 2kHz sine wave modulation available. Its size is 6.9" x 2.6" x 2" and it weighs 1.4lbs. It uses a standard 9V battery, and has provision for external 9V power, as well as an earphone jack for monitoring.


Lowe FX-1 in excellent condition. Obtained from England, the Lowe FX-1 reminds me of an updated (but much prettier) version of the Midland-series. It also has a slightly wider frequency coverage of  0.7 - 250 MHz. Like one of my favorites (the Kenwood DM-81), the Lowe stores its coils within its case: a plate on the back has a small thumbscrew (fingerscrew? <grin> ) and a compartment wherein the coils are stored. Overall, a very nice unit, with several attractive features-but all Lowes are not equal. In order for an FX-1 to function as a GDO, there is an entirely separate circuit that must have been added. Look for photos here soon.

 Lysco DipMaster GDO  w/all coils & manual, in excellent condition. LYSCO was a transmitter manufacturer in the 40s and 50s.

a McMurdo-Silver Model 903 wavemeter with original box, instruction sheet, and 4 plug-ins, in AS-NEW condition


an AS-NEW Measurements 59 complete with the suitcase carry-a beautiful instrument in incredible shape; this unit was believed to have been a 'Salesman's Sample' but apparently was not carried around much, if so. Also I have a partial body for parts; the 59LF Low Frequency Head; and (obtained separately from the above GDO) the 200-900MHz VHF/UHF Head.

a very good Measurements ("div McGraw-Edison") 159 . This unit is similar to, and may be considered a modernized version of, the Measurements 59. If anything, I like this one even better!!!


The MFJ201 covers 1.5-250MHz in 6 bands. My used one came with the original box, instruction sheet, and all coils-even the still-wrapped orig. 9V battery, in AS-NEW condition. The MFJ-201 has an FT-243 socket for crystal testing. Available new, it is a very good GDO for the money: accurate, portable, and reasonably rugged. Very similar to the Loadstar KDM-6 etc. series... except for a regular knob-operated injection level (instead of a thumbwheel.)

The MFJ203 is a band-switching GDO, covering from 1.75 MHz - 34.8 MHz in 5 bands. A frequency counter can be connected to the "FREQ OUT" RCA jack for higher accuracy. It manages bandswitching-instead of multiple plug-in coils-by putting the coils inside the box, and using a single plug-in coil for coupling. I believe that is the primary reason for the greatly limited bandwidth. It uses the standard 9 VDC battery, mounted internally. I obtained this one some time after manufacturing ceased because Amateur Electronic Supply still had one on the shelf in Florida. MFJ was absolutely no help in my quest for one-never even replying to my inquiries.

Midland Tr. Grid-Dip Meter Model 23-120 

Transistorized dip meter with a 0.5 to 150 MHz range, using 6 plug-in coils. Identical to the THORO-TEST GDM-3. Made in Japan



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