transmitter vlf

[WM6]

hi to all
I need a transmitter vlf 0-30k With relatively high.I've searched the internet but did not.
Please help me for a transmitter vlf.
with respect
jack

What mean "With relatively high"?

[Dave J.]

Dave, Your point is well taken. I guess I had pretty good results with the Q multiplier I built. Maybe because it was for the 1750 meter band. Randy

1750 meter band? No kidding! I was very active in LWCA late 80's - early 90's, had both a fixed and a portable beacon, built receivers, lots of technical articles published in club newsletters.

One article was about one of my projects that I called "fake active whip"-- a mobile clip-on CB antenna with a shunt tuning capacitor and a series resonant inductor going into a passive impedance matching network. As sensitive as most active whips, but of course was narrowband, either an advantage or disadvantage depending on your perspective. .....Funny, one of the other members (a rabid active whip fan) protested my calling it a "fake active whip".

It didn't occur to me that I coulda turned the thing horizontal, stuck a swivel handle on it, called it a treasure finder, and sold it for $5,000 a pop to gullibillies.

* * * * *

Down in the ULF band during that same era, I also played around with a portable earth current communications system running at 5 and 10 Hz straddling the fundamental Schumann resonance. The 5 Hz signal was doubled in the receiver to synchronously demodulate the 10 Hz signal polarity which was BPSK encoded.

--Dave J.

[Seden]

Current Communications System

That sounds very interesting. What kind of range did it have? Did you ever publish anything on it?

I was using Single Sideband with a couple guys in the San Fernando Valley. One in Studio City,the other in Granada Hills and myself in Simi Valley. We were on every Saturday morning for about 10 years. We also played with Amtor using the good ol' Pakratt version 1.o. I was ELU,then there was Dave Curry of Curry Communications who is PLI and Charles Faulker FPV,all done on 183.5KC. I had a 50' vertical with a 5/8 wave CB antenna with a wire around the ground plane and all shorted to the vertical element making one heck of a Capacitive hat. Did I stick with one watt? I may have run more (like 40 watts RMS). I figured if the FCC wasn't going to hold their end of the bargain with the light dimmers and other junk, I'd have to compensate for it.

Randy

[Dave J.]

I ran the dahdidit didahdahdah beacon from Los Banos, CA for several years. Approx. 35 foot max height whip vertical on the top of the house, no top hat, strictly 1 watt, I calculated radiated power at about 12 microwatts. Was often heard in the Bay Area, occasionally in the Fresno area, and occasionally by Mike Mideke who was I think something like 200 miles away out in the southern coast range wilderness with very good receiving equipment. Inasmuch as I don't know Morse code, never attempted manually keyed communication, just fixed ident beacons.

Designed from scratch and built a simple little 1750 meter band SSB receiver that fit in the palm of your hand, with as I recall about 100 Hz wide 600 Hz tone filter. Of course the antenna wouldn't fit in the palm of your hand, that's what the "fake active whip" was for although the receiver was designed to match 50 ohms so it could be used with almost any antenna. At a LOWFER convention near Santa Cruz we raced my receiver against a fancy commercial rig with a few custom enhancements that one of the other guys had, and it was a tossup which was best.

One of the funnier aspects of that convention was that out of about 35 club member attendees (there were about 40 more as guests), five of us were some combination of Dave/David Johnson/Johnston. Often got a bit confusing! although most of us sorta knew who some of the others were through club newsletters and personal communication. (This was all before the Web.)

Was interested in caving communications for a while and designed and built a crude proof-of-concept prototype hand-held portable 1750 meter band voice SSB transmitter and receiver system. Didn't work very well but it was a fun experiment.

--Dave J.