Re: [HCDX] Dxers Unlimited's weekend edition 2-3 December

["Prof. Arnaldo Coro Antich" <coro@xxxxxxx>]

Radio Havana Cuba

Dxers Unlimited's weekend edition for December 2-3 2006

By Arnie Coro

radio amateur CO2KK

Hi amigos radioaficionados, welcome to the weekend edition of your 
favorite radio hobby program... Dxers Unlimited with your's truly Arnie 
Coro at the microphone. Here is now item one... A new sunspot active 
region growing fast, and according to what scientists are watching, we 
may see solar flares during the next several days . Actually propagation 
condition on the HF region of the spectrum area between 10 and 20 
megaHertz were quite good during the past two days, and should continue 
to be good for at least two more days. More about the HF propagation 
conditions later , at the end of the program when Arnie Coro's HF plus 
low band VHF update and forecast... Here is now item two:

A very recent experiment here at CO2KK, my ham radio station consisted 
in running a step by step power output test, it was done on the two 
meters band, and the results show, once again, that with a good antenna, 
QRP or very low power operation is really possible. I took my 2 meters 
band station trough a power test that went down to 100 milliWatts or a 
tenth of a Watt while using a 6 dB gain antenna, effectively radiating 
when running the 100 milliWatts about 350 milliWatts, taking into 
consideration feedline losses. Groundwave contacts with stations up to 
one hundred miles away were possible when very slight tropospheric 
ducting conditions existed, and with absolutely flat conditions, the 350 
milliWatts effective radiated power could be heard regularly at stations 
50 to 60 miles away. But as you may guess to assure a good quieting of 
the FM receiver's noise, running 10 dB more power , that is about 3.5 
Watts was more than enough to keep very stable two way long 
conversations with stations in the 50 to 60 miles from Havana perimeter...

More about power output and antenna gain, in a few seconds , when Dxers 
Unlimited's weekend edition will continue, after a short break for 
station ID... I am Arnie Coro in Havana...

.................

This is Radio Havana Cuba, the name of the show is Dxers Unlimited 
amigos, and here now I am ready to continue discussing the topic, power 
output and antenna gain... For two meters band operation , an 
omnidirectional antenna with 6 dB gain will be a quite logical addition 
to your station , as it will provide around the compass coverage if your 
station is located out in the clear with no local obstructions that will 
stop or deviate the radio waves. A 6 dB antenna gain is not too 
difficult to achieve on the two meters band, and a lot easier to reach 
on the 70 centimeters band. On lower frequency bands, 6db antenna 
omnidirectional gain is much more difficult and expensive to achieve, 
and that's why the use of directional antennas is the way to go.

For those of you not familiar with decibels, let me say that 3dB means 
doubling the power, 6 dB is quadrupling the power, and a 10 dB gain is 
multiplying the power ten times. Something that can not be forgotten is 
that antenna gain is good for transmitting as well as for receiving too...

So amigos, all efforts to install better antennas are worth every minute 
and every single cent spent on them !!!

........

Dxers Unlimited's weekend edition continues now with Arnie's workshop, 
where the new hybrid REGENERODYNE receiver is still under test. Here is 
an update of the latest results... The tests with the computer clock 
modules that are being used to provide local oscillator injection to the 
front end of the REGENERODYNE, have proven to be both reliable and , as 
expected , very, very stable. They are fed with 5 volts regulated DC, 
and are easy to install. Switching frequencies is done by providing the 
selected module with the 5 volts output , as their output is connected 
to the broadband mixer in pararell in this first experimental setup, but 
I am planning to add a diode switching system in the next few days. 
 This prototype receiver has two local oscillators systems, one using 
the above mentioned computer crystal oscillator modules that deliver a 
square wave output that is ideal for feeding the four diode balanced 
mixer, and a second local oscillator using a standard NPN transistor and 
quartz crystals.

As explained during the previous edition of Dxers Unlimited , this 
receiver is a hybrid, an attempt to use the best features of both solid 
state and vacuum tubes.

The front end is now working very well, and the tuneable bandpass filter 
at the input will be added as a second option that will help to increase 
front end selectivity.

Don't worry amigos, I will keep you all pretty well informed of the 
evolution of this design that so far has surpassed by highest 
expectations.... Just to give you an idea, using the experimental hybrid 
Regenerodyne or EHR receiver on the 40 meters amateur band, in 
comparative tests with my excellent Kenwood TS820 transceiver, I have 
yet to find a difference between the two sets sensititivity to weak 
signals, absencse of spurious responses, images and overload... BUT, as 
expected the TS820's receiver can not be matched regarding its 
selectivity while picking up single side band stations, due to the shape 
of the IF filter's passband, something that the regenerative detector 
can not achieve for obvious reasons... Nevertheless when receiving CW 
signals, the two radios are producing almost identical results...

More about Arnie Coro's EHR , Experimental Hybrid Regenerodyne receiver 
in upcoming editions of your favorite radio program, the one you are 
listening to at this moment DXers Unlimited, from Radio Havana Cuba.

.......

QSL , QSL, yes QSL on the air to the many Dxers Unlimited listeners that 
keep sending reports about our new B-06 schedule, that so far has proven 
to provide much better listening to the specific target areas... And 
this is something that I want you all to know... Short wave broadcasts 
are targeted to specific zones, and although they sometimes may be heard 
in other areas, frequency planning does not contemplate providing 
service to zones outside the ones selected by the station to be the 
primary target areas...Just to clarify, let me give you an example... 
Radio Havana Cuba is beaming to the East Coast of North America on 6000 
kiloHertz from 00 to 05 hours UTC... From 00 to 01 we broadcast in 
Spanish, and from 01 to 05 in English to North America from 
approximately northern Florida, all the way up to the north of the 
Canadian Maritime provinces and Newfoundland... BUT, you can certainly 
pick up our 6000 kiloHertz signal in Chicago, or Toronto, although the 
antenna beam is not in that specific direction, so this explains why 
listeners in Central North America should listen to our English language 
programming between 01 and 05 hours UTC on 6180 kiloHertz, the frequency 
that is beamed into that specific direction ... Many times , while 
opening up my e-mail just after waking up and having a cup of nice Cuban 
black expresso coffee, I receive reports of Dxers Unlimited coming from 
New Zealand, Australia, Argentina or maybe South Africa or Greece... and 
that's to be expected too, because every antenna system has minor 
radiation lobes into other directions than the main beam of the array, 
and when propagation conditions are good, our station can be heard all 
around the world, by an Antarctic expedition scientist now in enjoying 
the southern hemisphere's summer season or maybe by the operator of an 
air traffic control radar station in an isolated region of Norway...

Si amigos, yes my friends, short wave propagation is always full of 
surprises, even when going trough solar minimum as it is happening right 
now !!!.

.......

This is Dxers Unlimited's weekend edition and here is now another 
popular section of the program... Antenna topics, that today will be 
devoted to indoor antenna, an option that is sometimes the only one at 
hand for many of this program listeners that live in apartment buildings 
or in areas of a city or town where outside antennas are forbidden by 
zoning regulations... Indoor antenna systems can improve performance 
over the typical portable radio's telescopic whip in a very significant 
way... You will notice less fading, and higher signal levels when adding 
a length of insulated wire to your telescopic whip, and fixing the wire 
with plastic tape to a window, or just taping it to a balcony rail... 
Yes, I am talking about a lot of difference... many decibels amigos.. 
Just to prove this point I ran two tests at my home QTH using the small 
analog Grundig FR 200 receiver...

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