Dxers Unlimited

Dxers Unlimited's weekend edition for 16-17 August 2003

By Arnie Coro

radio amateur CO2KK




Hello my friends, mis amigos that love radio all around the world ! Welcome to the weekend edition
of your favorite listener oriented and technically minded radio hobby program, coming to you via
short-wave and also via our streaming audio from www.radiohc.cu. I am Arnie Coro, radio amateur
CO2KK and here is item one for today. Solar active region 431 , now as large as planet Jupiter came
to an almost standstill in growth Saturday UTC, but it is still capable of producing large solar
flares in the M or even X categories. The solar wind speed has gone down, and I expect quieter
propagation conditions during the next three to five days. Item two: the huge power blackout that
affected the United States and Canada reminded many people about the importance of amateur radio,
when , as it has happened during previous emergencies the telephone systems collapsed due to traffic
levels that they could not handle. Once again, in both Canada and the USA, radio amateurs
demonstrated that they could handle emergency traffic even when all the AC power went down.
Congratulations to all radio amateurs in North America that once again demonstrated that the radio
frequency spectrum assigned to the amateur radio service is a really worthwhile decision by
consensus of all of the world's nations. Item three: Noise, radio frequency noise levels went down
to practically zero during the Eastern North America blackout, proving to many radio amateurs and
short wave listeners that their local power utilities are not taking good care of their power lines.
I heard several comments from radio amateurs in the affected areas that once the power came back,
the background noise level increased significantly . Some could even pinpoint that an adjacent area
that received the electrical service first was an important source of radio frequency
interference... Now you all can imagine that the radio frequency noise levels went really down when
AC power operated equipment was out of service and the only source of possible RF noise were battery
or emergency generator powered apparatus. Item four: Yes, ASK ARNIE continues to receive a lot of
e-mail , letters and postcards with very interesting radio hobby related questions... The latest
poll shows that it is now very close to the so far number one most popular section of Dxers
Unlimited, our HF propagation update and forecast that is always heard at the end of the program...
Margarita Delgado is my sound engineer and producer , standby briefly for more radio hobby related
information coming to you from Havana... I'll be back in a few seconds amigos...




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This is the weekend edition of Dxers Unlimited , and as you are listening to the program, a
worldwide amateur radio event is in progress. During this weekend ham radio operators all around the
world set up portable stations at lighthouses and lightships , and the event brings up a lot of
activity from stations wanting to work those special event locations. It is not exactly a contest,
it's just another nice way of enjoying ham radio and at the same time going out for a camping
weekend !!. Well my friends, ASK ARNIE now has a backlog... so let me see if today we can reduce it
a little by providing shorter answers to some questions. Question one: from Vince in Memphis ,
Tennessee USA, he wants to know what´s the difference between nickel cadmium and nickel metal
hydride rechargeable batteries. Well amigo Vince they are certainly two very different technologies,
so my advise is that you visit the world wide web site of several battery manufacturers and learn
from them about the differences between the nickel cadmium and the nickel metal hydride cells. If
you ask me about which type of cell will be best for your radio equipment, today the answer is that
the nickel metal hydride, or NIMH cells are the best choice,BUT, listen carefully, BUT, you must
recharge them with a battery charger especially designed for the NIMH cells, as they can be damaged
if recharged with a charger that is not especially designed for them...

QUESTION TWO: The VHF aviation band monitoring feature that went on the air here brought a lot of
feedback from listeners all around the world... And many of you want to know what antenna types are
the best for monitoring the lo VHF aviation band , especially the segment from 118 to 136 megaHertz.
Well amigos, the antenna of choice in my humble opinion is the classic DISKCONE...because it
provides the bandwidth required, is easy to build and at the same time has a vertical radiation
pattern ideal for the job. The DISKCONE also produces an almost perfect match for 50 ohm coaxial
cable. One of the listeners that wrote about VHF aviation band monitoring commented in his e-mail
that his homebrew DISKCONE fed with a 10 meter length of 50 ohm RG213 type cable, and installed on a
small 3 meters above the roof mast, was bringing in aircraft communications from up to 200 miles
away regularly, and during a recent tropospheric ducting event, he heard planes flying almost 600
miles away from his QTH... QUESTION THREE: This one came also from many listeners, and asks me why I
have insisted so much in homebrewing regenerative radio receivers instead of standard direct
conversion or super-heterodyne radios... Well amigos, the fact is that both vacuum tube and solid
state regenerative radios in my opinion are not only easy to build , but they also offer high
sensitivity and selectivity when properly operated, without having to invest in expensive electronic
components.. For example, my ultimate regenerative receiver is an almost perfect match for CW Morse
radiotelegraphy reception to my excellent Kenwood TS820 transceiver, one of the best ham radio sets
ever made. The TS820 when equipped with the 500 Hertz bandwidth filter is a dream radio... BUT , my
easy to build three vacuum tube regenerative will compete with the professionally built commercial
Kenwood set while working 40 and 30 meter CW DX.There are two important things to consider when
building a high quality regenerative or regenerodyne receivers, one is the need to use very high
quality air spaced ceramic insulated variable capacitors for the main tuning, the bandspread tuning
and in some circuits the feedback control or so called throttle variable capacitor. The other thing
that you must really take care about, is the use of a variable link coupling between the detector
and the antenna... It is amazing how the performance of a regenerative changes for the better when
you use high quality air spaced ceramic insulated capacitors and a well designed and built variable
link antenna coupling. I may add that operating a regenerative receiver from regulated DC voltages
is also essential in order to achieve best possible reception. Maybe one day in the future we will
see a really high performance regenerative radio receiver in kit form, so that the painstaking
process of gathering the parts and doing the metal work will not be required by the builders...By
the way , I have some new regenerative receiver's circuit diagrams that are in compact dot jpg files
format, so they can be sent via e-mail. Send for the REGENERATIVE RECEIVER INFO PACKAGE SECOND
EDITION by sending an e-mail to arnie@rhc.cu amigos, and remember that I will send it from my own PC
as soon as your mail arrives... As always its a real pleasure to help you all enjoy this wonderful
hobby by learning more about it !!!

....

Attention Radio Havana Cuba listeners around the world... your attention please... our engineering
department needs your help... We are now testing our 9600 kiloHertz frequency with a new
transmitter. It is on the air starting at 00 UTC, that is 8pm Eastern , 7 pm Central, 6 PM mountain
and 5 pm Pacific time... again the frequency is 9600 kiloHertz and the new transmitter under test
will be on the air from 00 to 05 UTC... The program we are broadcasting on that frequency is in
Spanish, but you can easily identify the station because we do ID quite often, and use the same
interval signal that is used on our regular English language programs... Send your reports to
arnie@rhc.cu amigos, and we will be sending back to you a special transmitter test QSL card that I
will autograph for you...Friday evening , when we first tested the new transmitter it was sounding
really good, with excellent modulation quality, as heard via ground wave here in Havana... We are
also now using on a regular basis from 05 to 07 UTC our 250 kiloWatt transmitter on 9820 kiloHertz
with the Pacific Coast of North America Curtain Array... By the way the new transmitter is a 100
kilowatt rig, but we are running it at 70 kiloWatts during the test period... The antenna used on
9600 kiloHertz is beaming to Venezuela, but many of you in NOrth America can pick up the back of the
beam quite easily according to my calculations .

You can also send your reports via AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana , Cuba, and
don't forget to include your postal mailing address in all of your correspondence to the station, so
that we can send you our nice QSL cards that verify your reception reports...

.....

This is Radio Havana Cuba, the name of the show is Dxers Unlimited, we are on the air and on the web
twice weekly with a program content that is targeted to both newcomers and oldtimers that are
enjoying this wonderful hobby... Here is now item five of today's show: one of the most important
things to learn how to do it, and do it well, is how to solder electronic components... your radio
hobby career be it short or long will always require that you know how to use a soldering iron and
the special type of rosin core solder that is used for electronics work... Never use acid flux or
acid core solder when working with electronic equipment amigos... The best solder now available has
about two percent silver, and melts at a rather low temperature, something that is becoming more and
more important as commercially built equipment tends to increase the density of components in order
to reduce the size ...You may want to start practicing how to solder by using a medium power
soldering iron, between 30 and 50 Watts will be ideal... Never attempt to learn how to solder using
low power soldering irons amigos !!!

And now, as always at the end of the program , here is Arnie Coro's Dxers Unlimited's propagation
update and forecast... The largest sized sunspot group at this moment stopped developing on
Saturday, but it is still capable of producing M or even an X class solar flare... The number of
sunspots is expected to diminish during the next several days, but this may change if the new
sunspot active region now about to rotate into view has a complex structure... Expect much better
radio reception during the next three days as compared to the previous three days, and the reason
for this improvement is the much lower geomagnetic activity expected. The number of sunspots from
optical observations is between 80 and 90, and the solar flux is hovering between 120 and 130 units.
Expect a nice an low A sub P or planetary geomagnetic disturbance indicator on Monday UTC if no
further coronal hole or flare activity changes this forecast. I will recommend the 19 and 16 meters
international short wave broadcast bands for easy listening from shortly before sunrise to about 2
hours after sunset in the case of 16 meters and much later into the local evening for the 19 meter
band. Amateur radio operator's best DX chances continue to be on the 20 meter band , with 30 meters
running a close second. See you all at the mid week edition of the program, and don't forget to
check our 9600 kiloHertz frequency in Spanish from 00 to 05 hours UTC and send your reports to
arnie@rhc.cu .