WYFR shortwave signing off

Family Radio’s WYFR shortwave service will be ending on June 30, 2013.

WYFR 50 years
WYFR 50 years

Shortwave transmitting is very expensive, and no doubt, competing IP distribution technology and diminishing returns on such investment must play a factor in this decision.  Family radio has been struggling ever since the world did not end as predicted in 2011.

I believe that site has fourteen 100KW HF transmitters and eighteen antennas of various type.  There is a complete photo album here: https://picasaweb.google.com/115519153277489147905/WYFR?noredirect=1#5149450014785168130 courtesy of Kent.

Kind of sad to see them go, I don’t know what their plans are after June 30.

HF VHF receiver diplexer

This is one of those posts that I started long ago and never finished. No time like the present to do the final revision and get it out there.

I have acquired one of those broad banded software defined radios, an Icom PCR-1000 to be precise, and all is well.  I am enjoying listening to various MF, HF and VHF radio stations.  However, there is a slight problem.  Very slight, almost too small to even mention, more of an inconvenience than a problem.  Still, if I am being inconvenienced, than others are too.  This issue is with the antennas.  My K9AY antenna works wonderfully from 500 KHz to 25 MHz or so.  My discone antenna works wonderfully from about 30 MHz all the way up to about 1 GHz.  In order to enjoy the full range of the receiver, I need to switch antennas.  I have a small switch on my desktop, but it seems inconvenient to reach over and switch it when going from the AM band to the FM band or something similar.  Therefore, I have decided that I need an HF/VHF receiver diplexer.  One would think that such hardware is ready made for such instances.   However, nothing I could find commercially would do the trick.

Thus, since I could not buy one, I decided to build one to add to my collection of receiver doo-dads and nick knacks.  The design is relatively easy, a back to back low pass/high pass filer system with a 50 ohm impedance throughout.  Something with a sharp cut off around 30 MHz or so:

Diplexor plot
Diplexor plot

Looks pretty good, 5th order Chebyshev filter, perhaps .1 dB ripple in the pass bands if well made.  Schematically:

HF VHF diplexor schematic diagram
HF VHF diplexor schematic diagram

Then it comes down to the building. Since this is going to be used in the UHF range, care and attention needs to be paid to the layout of the components and the design of the circuit board.  Some of those capacitance values are not standard, however, by using two capacitors in parallel, one can get pretty close.  Since this is going to be used for receiving only, I may be splitting hairs, however, I have found that well designed and built equipment is worth the extra effort.

The board layout looks like this:

HF VHF receiver diplexer board
HF VHF receiver diplexer board

I tried to keep the traces as close to 50 Ohm impedance as possible.

As one may be able to discern, C2 and C3 are in parallel to make 192 PF, C5 and C6 are in parallel to make 60 PF, and C7 and C8 are in parallel to make 163 PF.

The input and output RF connectors are whatever the builder wants to use, however, I would recommend at least BNC or type N for the VHF/UHF side.  My unit has all type BNC female connectors.   Parts list:

Nomenclature Value Mouser number Cost (USD)
C1 150 PF SMT 581-12065A151FAT2A 0.60
C2 12 PF SMT 581-12061A120JAT2A 0.25
C3 180 PF SMT 810-CGA5C4C0G2J181J 0.37
C4 68 PF SMT 77-VJ1206A680FXACBC 0.40
C5 50 PF SMT 80-C1206C500J2G 0.45
C6 10 PF SMT 80-C1206C100J2G 0.27
C7 3 PF SMT 581-12061A3R0CAT2A 0.22
C8 160 PF SMT 581-12063A161JAT2A 0.11
Case Diecast, 4.3 x 2.3” 546-1590WB 9.50

I chose a smallish, diecast aluminum case, which matches my other receiver gear.  The circuit board noted above is 2.9 x 1.7 inches, which is a little bit small.  I used 18 gauge wire between the input/output connectors and the board.

The inductors were made by hand.  I used a small screwdriver as a winding form, making the turns tightly then spreading them out to the proper distance.

Inductor chart:

Inductor Value (nH) Diameter (mm) Turns Length (mm)
L1 173 8 6 9.5
L2 468 8 10 9.8
L3 414 8 9 8.7
L4 146 8 5 7.2
L5 186 8 6 8.6

The most expensive part was the circuit board, which cost about $16.00.  The rest parts were about $18.00 including shipping.

As built photos:

HF VHF diplexor with components installed
HF VHF diplexer with components installed
HF VHF diplexer input side
HF VHF diplexer input side
HF VHF diplexer completed.
HF VHF diplexer completed.

I have installed this already and it works great. I will need to get the spectrum analyzer out and run some signals through the various ports to see the attenuation and 3 db roll off points.

Goodbye, RCI 1945-2012

RCI logo
RCI logo

In yet another example of government sponsored international broadcasting ending, Radio Canada International calls it quits after 67 years.  Effective June 24, all broadcasts from RCI’s Sackville shortwave relay site will cease.  All satellite distribution will end and seventy five percent of the RCI workforce will be laid off.  This means the end of almost all RCI original content.  The good news, according to the press release, is that RCI will continue on webcasting.

This is due to budget cuts to the CBC, which administers RCI.  The Canadian Parliament cut the RCI budget from $12.3 million CAD to $2.3 million CAD for 2012.  This cut in expenditures is saving each Canadian resident approximately $0.35 CAD per year.

Thus, this weekend is the last chance to hear RCI or CBCNord Quebec on any HF frequency.

I listened to RCI for many years, until they drastically reduced their English language shortwave broadcasts to North America in 2006.  Simply put, HF broadcasters are folding up shop and moving toward web based distribution networks.  Those HF transmitters are expensive and they do not maintain themselves.

One drawback of this scheme is government censorship.  It is very easy to the government to block access to sites via internet firewalls.  It is very difficult to completely jam a radio station.

And perhaps those considerations are not important.

RCI transmitter site, Sackville, NB
RCI transmitter site, Sackville, NB, courtesy of Wikipedia

I wonder what will happen to their transmitters after sign off?  According to the wikipedia article there are nine HF transmitters in use, with power levels ranging from 100-300 KW.  They are likely to be hauled away and scrapped, the building torn down.