Bad capacitor rotor contacts in vintage equipment are a major problem.. Especially in dipmeters, causing erratic performance and false dips..... Always clean the rotor contacts ! 73 de PZ1CD
@AMStationEngineer
9 жыл бұрын
A very well-produced, and thoroughly descriptive video. Many thanks for posting! Way back when, in the late '70s, I had a Motorola Motrac VHF Hi-Band transceiver on the bench which was the victim of "relay chatter" when another Motrac, which happened to be a Lo-Band model was keyed up. A call to Motorola Tech Support outlined a procedure which utilized a Dip Meter, which I was forced to borrow. The cure wound up being a 47µh choke, and a resistor having to be installed on the coil side of the relay. It was theorized that the Lo-Band transceiver generated a harmonic on the secondary frequency, which approximated the resonant frequency of the coil length used in the transmitter/receiver cut-in/cut-out relays used by Motorola in all of their Motrac line.
@kargocult
7 жыл бұрын
Good, thorough video! Useful info on the hair trigger osc adjustment.
@Wenlocktvdx
5 жыл бұрын
I recently acquired a Dick Smith Q1335 dip meter which is identical to the MFJ-201. I’ve tested several antennas with it and find the dips can be hard to find. The tunnel dipper looks like a big improvement. A nice piece of kit to have. de VK3YWB
@radiolens536
3 жыл бұрын
Until it broke I used (or tried to) a Trio dip meter, like your experience with your instruments, dips was really hard to find. A constant battle between trying to have a loose coupling only, and not having enough of it...
@Pwaak
9 жыл бұрын
Nice piece of Heathkit Equipment! Very good video! Thank You!
@bobweiss8682
7 жыл бұрын
Nice video. I have had a couple of these things drift across my bench over the years, and both of them exhibited the hypersensitive control symptom. I think it was inherent to the design, as others have reported similar results.
@jefftranter
7 жыл бұрын
Thanks, that's good to know.
@analog_guy
Жыл бұрын
The Tunnel Dipper rapidly developed a poor reputation after it was introduced due to the hypersensitive gain control and generally very frustratingly-touchy operation, often requiring multiple gain adjustments to span the range of a single coil, and often producing false responses. Heathkit eventually replaced the Tunnel Dipper with a dip meter that used a field effect transistor (FET) and provided much-smoother behavior. The Tunnel Dipper was an innovative design, but the circuit should have been improved before it was marketed. Unlike other dip meters that limit the oscillation amplitude via self-regulating feedback schemes, the Tunnel Dipper simply allowed the oscillations to grow to the maximum level the tunnel diode could sustain. Thus, its oscillation contained harmonics, and the oscillation amplitude dipped only a tiny amount when coupled to a resonant circuit under test. To compensate for the small change, the designer used a high-gain dc amplifier to drive the meter. The amplifier is an unbalanced circuit, having a lot of offset and drift, requiring careful adjustments by the user to keep the meter from being “pegged” either one way or the other. I purchased one of these Tunnel Dipper kits from Heathkit and have had it ever since. I also added resistors around the gain control to reduce the control’s sensitivity, but the unit remains rather touchy to operate. As noted by other owners, the foam that held the coils in the cover has deteriorated and crumbled. I have replaced that black foam with newer soft white plastic foam.
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