[Lf] [Fwd: [Lowfer] Palomar VLF converter?; antenna?]

[Andre' Kesteloot]

Lyle Koehler wrote:

> Dave Benham wrote:
> >
> > Although I've been a ham for 40 years, I am a relative newbie to VLF.  I
> > understand that the VLF RX portion of most ham rigs is pretty poor so I am
> > looking at alternatives.
> >
> > Is the Palomar VLF converter OK for a starter?  Any opinions?  If not OK,
> > what are some other opinions?  I have a variety of receivers around here
> > (HRO-60 with standard coil set, McKay-Dymek, etc. -- although most are on
> > the shelf collecting dust).
> >
> Some of the old tube-type rigs are pretty good on LF. If the coil set
> for your HRO-60 includes one for the 150-500 kHz range or thereabouts
> I'd try that first. There is a mini-review of the Palomar VLF converter
> in the latest (January) QST. Many modern receivers have general coverage
> down to 100 kHz, and make excellent LF receivers with a simple active
> antenna or preamp in front of them. My web page has diagrams for several
> tuned loop preamps. Loop antennas are my personal preference on LF, but
> a G5RV or a ham-band dipole will usually work. Just make sure the
> antenna doesn't a) go through a ham-band tuner or b) have a balun or
> matching transformer in the line that shows DC continuity across the
> coax terminals. Choke-type baluns made by coiling up a bunch of coax or
> putting ferrite beads on the outside of the coax are OK, but most HF
> transformers or transformer-type baluns will severly attenuate LF
> signals.
>
> I've been assuming you will want to do most of your listening on LF (30
> to 300 kHz) rather than on VLF (3 to 30 kHz). About the only thing
> you'll find below 30 kHz are the Navy transmissions using encrypted MSK
> RTTY. Maybe interesting to see how many signals you can detect, but the
> novelty wears off pretty fast :-) "Natural radio" signals are another
> story, but for that you need a different type of receiver. Basically an
> audio amplifier connected to a whip antenna. And you're not likely to
> hear much on a natural radio receiver other than 60 Hz and harmonics,
> unless you are a long way from the nearest power line.
>
> By the way, the latest ARRL Antenna Book has a chapter on Lowfer
> antennas; transmitting and receiving. A pretty concise and accurate
> treatment of the subject (although it looks like there's an error in the
> battery connections on the active antenna schematic).
> --
> Lyle, K0LR
>
> http://www.computerpro.com/~lyle
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