[Lowfer] VLF

[Todd Roberts]

Hi Jay,
All good points on VLF reception. Congratulations on your good copy of SAQ this Dec 24.
Conditions here in coastal SC were not very good that night with local rain and high static at
the time so I did not attempt to try for SAQ.

One thing I have found in the past that works very well on VLF  is to try to have a very high front end RF
selectivity. That seems to help limit static crashes from getting into the receiver front end and causing
more trouble down the line although having high I.F. selectivity and a good noise blanker in the receiver helps
a lot also.

Some of the best reception I have had in the past of SAQ was using a very high-Q ferrite-core loop antenna.
The one I used was built from a kit by Jim Hagan that he sold a number of kits back in the 80's. It has several high-Q ferrite rods glued together
for an equivalent rod of almost 30 inches in length. The RF bandwidth of the loop is very narrow I
would say a few hundred Hz at the most down around 17 kHz. This gave a very high front end RF selectivity.

Running the receiver and antenna on batteries can help a lot also. If at a home location kill the main breakers
for house power.

Someone might experiment with a regenerative RF  preamp also for a similar effect on VLF when used with
a different antenna.
73 - Todd WD4NGG


-----Original Message-----
From: jrusgrove <jrusgrove at comcast.net>
To: Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands <lowfer at mailman.qth.net>
Sent: Wed, Dec 25, 2013 12:09 pm
Subject: [Lowfer] VLF


Andy

After many years chasing VLF signals I've come to the conclusion that the best 
approach is to use 
the smallest antenna possible ... the main requirement being that the antenna 
should be able to 
produce sufficient 'band noise' to overcome the receiver noise. A small antenna 
minimizes the amount 
of  noise pickup thereby easing the noise mitigation that must be carried out. 
Small 'amplified' e 
probe or loop antennas are ideal for this application.




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