Tag Archives: Bill Hemphill (WD9EQD)

Guest Post: Switching a Remote Antenna, Low Noise Amplifier, and an Antenna and Audio Between Two Radios

Many thanks to SWLing Post contributor, Bill Hemphill, who shares the following guest post:

Remote Antenna Switching Remote Low Noise Amplifier Switching and Switching an Antenna and Audio Between Two Radios

by Bill Hemphill, WD9EQD

Remote Antenna Switching

I have two YouLoop Antennas. I had been placing them at right angles to each other. I would then put one of them on the AirSpy software defined radio. But manually switching from one antenna to the other was a real pain. If only there were a way to electrically switch between the two antennas.

It would be nice to place the antennas remotely from the radio (and computers) and then have some sort of remote switch that would select an antenna and then a single feed line to the radio. It was research time.

The YouLoop and the Airspy both use SMA connectors. An SMA switch would be required. A little research and I came across the following small board that can switch between two SMA antennas:

From Amazon Description: 50 Ohms RF Switch Module, 3-5V Remote Wireless RF Switch Single Pole Double Throw Board Input Output Impedance for DIY Electric Doors (HMC349)

This board is perfect for RECEIVE only projects. Apply 5V to the board and then 5V to the VCC (control pin) to switch from RF1 to RF2.

Now that I had the SMA switch module, a way to actually do the switch remotely was required. Maybe WI-Fi or Bluetooth module would do the trick. I found a nice Wi-Fi module on Amazon that looked like it would do the trick:

Amazon Description: DIYmalls SV Safe Low Voltage WiFi Wireless Switch Module DC 5V-24V Phone APP Remote Control Smart Home for Amazon Alexa Google Assistant

But do I really want to use a phone app to switch antennas. Further investigation discovered a really neat module that uses a Car Fob type control:

Amazon Description: RODOT Mini Relay Wireless Switch, 433Mhz Remote Control Relay Switch, DC 6V 12V 24V 1CH Channel Relay Wireless Secure RF Transmitter and Receiver kit, Momentary Toggle Latched Mode

BIngo!! I could just press a button and switch antennas. But a problem quickly arose. I hadn’t fully read the description of the RODOT switch:

The blue output wire is ALWAYS Vcc (input voltage)! The device only switches the ground.

So the RODOT switches the ground but the HMC349 uses positive voltage to switch. OOPS. Next step was to place a latching relay to take the on/off ground and convert it to on/off positive. Again, another nice board was found:

Amazon Description: HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger

The nice thing about the Relay Module is that it can be latched either High or Low, so the RODOT switching ground can be used to latch the relay and then provide a positive voltage to the HMC349 antenna switch.

All modules are powered by 5V. There are other modules available that use higher voltages. But I wanted to be able to use a 5V power source for everything.

I learned a quick lesson on the first layout I did. I had directly connected the antenna cables to the HMC349 module. A quick accidental side yank on one of the antenna cables and the SMA connector tore off the board. A replacement board and some quick wiring and I had a workable antenna switch that with the press of the car fob button, either antenna could be selected.

I found a nice small plastic box that allowed for the HMC349 module to be suspended between SMA bulkhead connectors. By using bulkhead connectors, there is no strain placed on the HMC349 connectors. The relay module was attached to the box lid. The modules are mounted using brass standoffs. The finished box is about 3”x4”x 2” high. Either battery or a 5V wall module can be used to power it.

Overall, I’m quite pleased with the results. I find that sometimes switching antennas (and their orientation) can make a big improvement in the signals. Other times, there’s very little difference.

Remote Low Noise Amplifier along with Antenna Switching

Now that the antennas can be switched, it would be nice if a Low Noise Amplifier could be switched in and out of the circuit. Something like the Lana HF Barebones LNA made by NooElec:

For testing purposes, I first did a quick layout of just using one antenna with the ability to switch the LNA in and out. Note: I took a gamble on hooking the antenna cables directly to the HMC349 modules. Luckily, the SMA connects didn’t tear off the boards.

Two HMC349 modules are used. The first module selects the bypass or the LNA. Likewise, the second module also selects either the bypass or LNA. Note that the second module is turned upside down so that the switches match up when activated. Two modules were used so that the LNA is totally switched out of the circuit. Continue reading →

Spread the radio love

Ghosts in the Air Glow HAARP transmission: August 14, 2023, 03:30-4:30 UTC

2 Replies

Many thanks to SWLing Post contributor, Bill (WD9EQD), who writes:

“Ghosts in the Air Glow” by Canadian artist Amanda Dawn Christie is a transmission art project through HAARP that mixes audio and images from the transition between Earth’s
atmosphere and outer space.

Shortwave radio listeners from around the world are invited to tune in and submit reception reports online through the project’s website.

Website:

https://ghostsintheairglow.space/

It’s a one hour program consisting of ten parts:

https://ghostsintheairglow.space/transmission/august-2023

Frequencies haven’t yet been posted.

There are also archived videos of her 2022 & 2019 projects.

Her radio art projects are always interesting.

73
Bill WD9EQD

Spread the radio love

Bill identifies a “credit card” HT in the movie “Hollow Man”

3 Replies

Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD) who writes:

Hi Thomas,

Last night, I was watching the movie “Hollow Man.” Being a ham, I’m always watching for ham gear being used in movies. Quite often they use various Kenwood or Icom handheld radios.

At about 1 and half hours in the movie, I caught a glimpse of what I thought was one
of the more usual (and unlikely) ham heldhelds:

Just from this screen clip, I was pretty sure that I was looking at the Alinco DJ-C5 credit card HT.

I was able to capture another clip that confirmed it:

In the late 90’s, Alinco made three credit card radios; DJ-C1 for two meters, DJ-C4 for 440 and finally the DJ-C5 dual band that could also receive the aircraft band.

The C1 and C4 were earpiece only radios while the C5 had a small speaker added which made it a lot more usable.

They are quite amazing little radios. It was great fun seeing them appear in a movie.

Here’s one of mine with a ink pen next to it to show size:

Thank you for sharing this, Bill! I remember when these credit card-sized HTs were on the market and I wanted one if for no other reason than to feel like a spy! Great catch, OM!

Spread the radio love

Airspy HF+ Discovery & Shortwave Portables: Having Fun with the Airspy YouLoop!

20 Replies

Many thanks to SWLing Post contributor, Bill Hemphill, who shares the following guest post:

YouLoop Antenna Fun

by Billy Hemphill WD9EQD

Like many listeners, I live in an antenna restricted community. While I have strung up some hidden outdoor wire antennas, I have found that they didn’t really perform that much better than just using the telescoping antenna with maybe a length of wire attached. The biggest problem (whether indoor or outdoor antenna) has been the high noise floor.

A few months ago I bought an AirSpy HF+ Discovery SDR receiver. I had already owned a couple of SDRPlay SDR receivers, but the high noise floor limited their performance. I had read good reviews about the AirSpy, especially its performance on the AM Broadcast band and the lower shortwave bands.

I have about 80 feet of speaker wire strung from the second floor and across the high windows in the living room. This does perform fairly well, but the high noise floor still exists.

A couple of weeks ago, I bought the YouLoop Magnetic Loop antenna from AirSpy. I gave it a try and am amazed at the lower noise floor compared to the indoor wire antenna.

Wire Antenna vs. YouLoop–some examples:

AirSpy with Wire Antenna

AirSpy with YouLoop

AirSpy with Wire Antenna

AirSpy with YouLoop

AirSpy with Wire Antenna

AirSpy with YouLoop

Dramatic reduction in the noise floor. I’ve done a lot of playing around with it and find that the YouLoop picks up just about the same stations as the indoor wire antenna does. But with the lower noise level, the YouLoop makes it more enjoyable to listen. Overall, the YouLoop is now my main antenna.

YouLoop with a Portable Radio

It works so well with the AirSpy, I started wondering if I could use it with a portable radio, like the Tecsun PL-880. But the AirSpy website has the following note:

Note: It is very likely your third party radio will not be sensitive enough to operate with the YouLoop properly. We have even seen self-documented failed attempts to build pre-amplifiers to compensate for the lack of sensitivity and/or the required dynamic range in third party radios. Use your brain, and eventually an Airspy HF+ Discovery.

Doesn’t sound like it will work with portable radios. BUT, I’m always one to try anyway.

Tecsun PL-880

Since the YouLoop has a SMA connector, I bought a SMA to 1/8” phone jack cable. Plugged it into the PL-880 antenna jack and found I had almost a dead radio. Very few stations heard. But in playing around, I accidentally touched the phone plug to the telescoping antenna and instantly got strong signals.

I did some very unscientific tests. I attached the YouLoop through the side antenna jack, did an ATS scan, then did the same with the YouLoop clipped to the telescoping antenna. Also did a scan with just the telescoping antenna fully extended.. I got some very interesting results. These were done one after the other, so there can be differences in signal fading, etc.

I have repeated the above test several times at different hours. While the actual number of ATS stations varied, the ratio between them remained fairly consistent to the above numbers.

From the above, it appears that the telescoping antenna circuit is more sensitive than the 1/8” antenna jack circuit. Maybe some attenuation is being added to the 1/8” jack since it’s more likely a higher gain antenna would be used there. Can anyone confirm that the circuit indeed attenuates thru the antenna jack?

The YouLoop seems to be a decent performer when directly clipped to the telescoping antenna. While not as good as a high gain outdoor antenna would be, it definitely is usable for indoor uses.

I also tested it clipped to the antennas of some other portable receivers. Tecsun S-8800, PL-330, Panasonic RF-2200 and Philco T-9 Trans-World receivers. All showed an increase over just using the telescoping antenna.

Some interesting notes:

The Tecsun PL-330 saw the same reduction in signal when directly plugged into the antenna jack as opposed to clipping on the telescoping antenna.

The Tecsun S-8800 did not show that much of a drop. I basically got the same number of stations when clipped to antenna as when I connected to the BNC jack:

In conclusion, I find that I can use the YouLoop with my portable radios to increase the signals on strong stations when used indoors. And it is quite the performer when used with the AirSpy HF+ Discovery SDR receiver. It easily portable and I find that I move it around the house as I need to. I just hang it off a window curtain rod. I may just order a second one so that my family room radio has one permanently attached to it.

Click here to check out the Youloop at Airspy.com.

Spread the radio love

Guest Post: Simple Android Database Part 2

Simple Android Database-PART 2

by Billy Hemphill, WD9EQD

In the first part, I showed how you could easily take a spreadsheet and create a simple database for viewing on an Android phone/tablet. The examples used in that article was two spreadsheets of radio schedules – one for Shortwave and one for FM Radio Programs. See the following link to the original article: https://swling.com/blog/2021/10/guest-post-radio-schedules-in-a-simple-android-database/

There are many lists on the internet of various radio databases. If the database can be downloaded as either a CVS file or a spreadsheet, then it is possible to load it into the PortoDB app on the phone tablet. I’ll show how this can be done with two popular databases that I reference all the time.

EIBI Data Base

Most of you are probably familiar with the EIBI database of shortwave schedules. Many of the Shortwave Schedule apps on the Phones reference this database. For example, I use the Skywave Schedules on my phone. While it does allow for me to search by many parameters, I thought it might be fun to have it in a PortoDB database. Plus it would be interesting to see how PortoDB performs with a large data set. Continue reading →

Spread the radio love

Guest Post: Radio Schedules in a Simple Android Database

7 Replies

Many thanks to SWLing Post contributor, Bill Hemphill, who shares the following guest post:

Radio Schedules in a Simple Android Database

by Bill Hemphill

I am a program listener. I really enjoy listening to various radio stations direct and by internet streaming. Over time, I have come up with a couple of spread sheets that lists the program, station, time, date, etc. For example, following is the spreadsheet for the shortwave radio programs/stations that I enjoy:

As the program schedules change, I update the spreadsheet. This has worked quite well for me. I usually sort on the weekday and then print out the spreadsheet as a list by time and frequency for each day.

While this method works, it does mean that I have these multiple page printouts that I have to refer to. This got me thinking that it would be great to have this on my Android phone/tablet. Then I could refer to it no matter where I was located.

At first, I tried to use Google Sheets, but found that using a spreadsheet on the phone or even a tablet to be a pain. I then tried entering it into a calendar program, but also found that very cumbersome. Continue reading →

Spread the radio love

Guest Post: Remembering the great “Radio Moving Day” of 1941

4 Replies

Many thanks to SWLing Post contributor, Bill Hemphill, who shares the following guest post and addendum to his most recent post on BBC Re-Tune messages:

Radio Moving Day

by Bill Hemphill (WD9EQD)

After listening to the BBC “Re-Tune” broadcasts, it reminded me of when the United States had its own “Re-Tune” day on March 29, 1941. It was referred to as “Moving Day”.

At 3:00 am, 802 of the 890 radio stations moved frequency. Following are a couple of articles about this day:

http://www.jimramsburg.com/the-march-of-change-audio.html

https://www.radioworld.com/columns-and-views/in-1941-stations-confronted-39moving-day39

And a previous SWLing Post article:

https://swling.com/blog/2021/04/am-radio-history-80th-anniversary-of-the-havana-treaty/

Like the BBC, there were also broadcasts helping listeners to get ready:

Audio Clip 1

Audio Clip 2

Audio Clip 3

Audio Clip 4

I love how it was used as an opportunity to get the radio listener to call on the radio technician to re-program the radio push buttons. And of course while the technician is there, have him do a full alignment and maybe replace a tube.

The March 1941 issue of Radio and Television Retailing (Pages 16-17) had the article “Radio’s Opportunity for Contact”.

Link: https://worldradiohistory.com/Archive-Radio-Retailing/40s/Radio-Retailing-1941-03.pdf

While the entire article is an interesting read, the first few paragraphs sums up the opportumities:

THE OPPORTUNITY for contact with consumers using pushbutton-tuned radios., afforded by dramatic March 29 broadcast station frequency shifts, represents an absolutely unique invitation to move more major merchandise, with the promotional expense at least partially covered by service and accessory sales.

Imagine what slick automobile salesmen could do if roads were suddenly altered in such a manner that 10,000,000 cars required some adjustment to operate properly, what refrigerator salesmen might accomplish if a change in current necessitated motor manipulation, how laundry equipment salesmen would positively gloat over the glut of prospects if that many people with old machines actually asked them to call.

Calls make sales, as the records of many home specialty retailers conclusively prove, and the beauty of this particular opportunity to make them lies in the three-fold fact that cold-canvassing is completely unnecessary, that the motivating power of any campaign built around it is obviously not just trumped-up by the trade and that only dealers selling or servicing radios can capitalize in all departments of their business.

So valuable from a major merchandising sales angle is the opportunity to call upon consumers afforded by the necessity for changing pushbutton settings that we suspect many radio retailers will hesitate to charge for this adjustment.

This may be particularly true where consumers so contacted are obviously prospects for new merchandise and will undoubtedly occur in some instances where customers are still being carried on time-payment accounts.

The Feb 1941 issue of Radio Service-Dealer (Page 8) also stressed the opportunities.

Link: https://worldradiohistory.com/Archive-Radio-Service-Dealer/40s/Radio-Service-Dealer-1941-02.pdf

From Page 8:

Reallocation of Broadcast Frequencies M arch 29th Opens Big Job For Service men Resetting Nation’s Push-Buttons

YOUR JOB

There are approximately 10 million push-button receivers in operation in this country. It will be your job to re-set the buttons for the new frequencies in the shortest possible time and with the least amount of confusion. It will also be your job and your opportunity to inspect these receivers for faulty operation. No such opportunity is likely to present itself again, so make the best of it.

And on page 7 of the Mar 1941 issue of Radio Service-Dealer has the article FREQUENCY REALLOCATION SERVICING PROBLEMS

Link: https://worldradiohistory.com/Archive-Radio-Service-Dealer/40s/Radio-Service-Dealer-1941-03.pdf

The first Problem discussed is the IF Frequency:

1A—If a station with a strong signal intensity happens to be operating on double the frequency of the intermediate frequency of a receiver, there is liable to be a heterodyne whistle. The frequency of 455 kc has been used as the standard intermediate frequency on receivers manufactured in the United States. One main reason for selecting this frequency was that the broadcast frequency of 910 kc was assigned to Canada and, therefore, the possibility of a heterodyne note being produced on a receiver in the United States was at a minimum. Under the terms of the reallocation several American stations will be moved to 910 kc thus producing a problem in the cities where these stations are to be located. If a heterodyne note is heard due to this cause the remedy is to shift the intermediate frequency to one side or another.

Thank you, Bill, for shedding more light on Radio Moving Day and, especially, providing us with the broadcaster and technician’s point of view.

Spread the radio love