SRF-59 coupled to ferrite bars


lrdheat
 

Dear folks,

Gary's mating of a large ferrite bar to the SRF-59 would be highly
desirable. Like another earlier post, I shy away from opening radios
as "disaster would be sure to follw". I am including a part of a note
that I sent to Gary describing my experience today with inductively
coupling the SRF-59 to a couple of radios with large ferrite bars.
There are some nice pluses to using a radio as opposed to tunable
ferrite bars or selectattena types(sp?)in that the tuning display of
the radio will provide an excellent indication as to what frequency
the ferrite bar is tuned to!

I found today that the coupling my SRF-59 with the antenna in either a
SANGEAN PR-D5, or with a SONY ICF-EX5 makes the SRF-59 slightly more
sensitive than either set. The PR-D5 has to be on for this coupling to
work. That is good and bad...it means that I am using the PR-D5's
batteries during a dxing session, but it also means that it is easy to
properly tune the PR-D5's antenna to the frequency that I hope to peak
on the SRF-59!. The coupling has a very sharp null, and a fairly
narrow peaking window...just offtuning 10 KHz is noticable, and an
offset of 20 KHz is quite noticable. In the case of the analog SONY
ICF-EX5, the EX-5 need not be on...tuning the sliderule indicator to
the frequency of interest results in a pronounced peaking of the
signal on the SRF-59 with about as much of a boost as produced with
the PR-D5.

The attraction of your experimental homebrews is that it does not
employ two items that need to be tuned for each frequency of interest,
and that it is much more portable, has a much smaller footprint.

I'm back...this is a neat refreshing change from the swl'ing that I
had been doing, and harkens back to my days as a youngster staying up
to all hours of the night listening to dx on a 6 transistor set using
the radiator in my room as an antenna.

What type of tips might you have for trying to catch trans Atlantic dx
from Laredo, TX?

Heatwave


Gary DeBock
 

Hello Richard,
 
     Thanks for your comments, and the information on your SRF-59 inductive coupling with the PR-D5 and ICF-EX5.  Your approach is one that's new to me, although booster bars (such as the excellent units kindly made and given by Gil Stacy and Kevin Schanilec) are heavily used here, and most of the TP's I logged on the ICF-2010 last fall were inductively coupled from the Quantum Loop 2.0+, which of course required tuning twice.
 
     The loopstick transplants, especially the latest (SPR2 7.25" and SPR3 14.5") experiments, generally boost the SRF-39FP sensitivity past the ICF-2010 stock level, but not past the 2010 + Quantum Loop level. The 2010 + Quantum Loop is a very effective combination, although it does require tuning twice. It would be like a dream to construct a stand-alone modified Ultralight, with the same sensitivity as the 2010 + QL combination.  I think it's possible, but the loopstick may not fit through a standard doorway  :>)
 
     Loopstick transplant science has had a tremendous boost because of the Ultralight phenomena, but these improvements are not limited to Ultralights.  It would now be routine to give radios like the ICF-2010 and ICF-SW7600GR larger, more effective antennas, assuming the owner could live with an external mounting system.  My own impression is that an ICF-2010 with a 14" loopstick could outperform a 2010 + QL combination, but we will never know for sure until somebody actually tries it. 
 
     Thanks again for your comments, Heatwave, and the "Super Prison Radio 2" article should be finished soon, giving everyone detailed instructions on making this DX dynamo from a commonly-available 7.25" loopstick. 
 
                                                                                                              73,  Gary  




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