Friday, 22 October 2021

RASPBERRY PI ~ HAM PI

HAM RADIO SOFTWARE SUITE
FOR YOUR RASPBERRY PI

HAM PI by W3DJS

I have recently built a nice ham-radio-clock for the shack using an old computer monitor, a Raspberry Pi 3 and ClearSkyInstitute's amazing HAMCLOCK software. It's a very worthy addition to the shack and I recommend it to everyone.

So with my little Pi3 tied up to that task, I purchased a used (but like brand new in the box) Model Pi400. Unlike the Pi3, this package came complete with everything you need (apart from a monitor) to have yourself a decent-spec home computer, including the keyboard, mouse, power-supply, leads, SDcard with operating system and even a comprehensive Guide Book. It's a self-contained unit with the Pi 'motherboard' built into a compact and attractive keyboard.

So what you have here is an extremely compact PC which you can use for running various tasks without tying up your main PC. And that's why I got this because it seems to me, that every time I want to use the big computer, it's already running some radio-related task. With the Pi400 and HamPi software, I can pretty much run everything I want in the shack - we'll see!



The specs are as follows....

  • Processor: Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.8GHz
     
  • RAM: 4GB LPDDR4-3200 
     
  • Connectivity: Dual-band (2.4GHz and 5.0GHz) IEEE 802.11b/g/n/ac Wireless LAN, Bluetooth 5.0, BLE Gigabit Ethernet 2 × USB 3.0 and 1 × USB 2.0 ports 
     
  • GPIO: Horizontal 40-pin GPIO header 
     
  • Video & Sound: 2 × micro HDMI ports (supports up to 4Kp60) 
     
  • Multimedia: 265 (4Kp60 decode) 264 (1080p60 decode, 1080p30 encode) OpenGL ES 3.0 graphics 
     
  • SD card support: MicroSD card slot for operating system and data storage 
     
  • Keyboard: 78- or 79-key compact keyboard (depending on regional variant) 
     
  • Power: 5V DC via USB-C connector 
     
  • Security: Security lock port 
     
  • Cooling: Large internal heatsink plate and underside vents Operating temperature: 0°C to +50°C 
     
  • Dimensions: 286 mm × 122 mm × 23 mm (maximum)
To make the Pi400 even better than it already is, you can download the software suite I mentioned above, which was designed purely for Ham Operators. It's a staggering collection of really useful apps called HamPi by W3DJS and it includes the HamClock mentioned at the top of the post. I doubt very much that I'll find a use for all the software (I don't even understand what half of it's for, lol) but there's definitely some stuff on there that will free up my Windows PC. And best of all, this package gives you lots to experiment with, and that's the big attraction of the hobby to me.


Conveniently, the HamPi software is downloadable as a 4Gb image which you simply transfer to a fresh SD Card and then insert into your Pi. Switch on and BOOM, all ready to go!

Here's a list of the Apps that are currently included in the package...


General Ham Radio Applications
==========================
HamLib - Ham Radio Control Libraries
grig - graphical user interface to the Ham Radio Control Libraries
CHIRP - Radio Programming Software
APRS Message App for JS8Call - GUI to send APRS messages via JS8Call
QTel - EchoLink client
QSSTV - Slow Scan TV (e.g. "Fax")
Gpredict - Satellite prediction
FreeDV - Free digital voice vocoder
BlueDV - Client for D-Star and DMR
WsprryPi - WSPR software
ADS-B Flight Tracking Software
Pi3/4 Stats Monitor - by W1HKJ
VOACAP - HF propagation prediction
GPS Support
Auto WiFi Hotspot - Automatically turn your Pi into a WiFi hotspot when in the field!
wxtoimg - NOAA weather imaging software
twHamQTH - an online callsign look up program
twclock - a world clock and automatic ID for amateur radio operators
acfax - Receive faxes using your radio and sound card
colrconv  -  convers client with sound and ncurses color support
D-Rats 0.3.9 (by new maintainer Maurizio Andreotti) - A communication tool for D-STAR
fbb - Packet radio mailbox and utilities
gcb - Utility to calculate long and short path to a location
glfer - Spectrogram display and QRSS keyer
Xdx is a DX-cluster client
DXSpider - DX Cluster Server
fccexam - Study tool for USA FCC commercial radio license exams.
gnuais / gnuaisgui - GNU Automatic Identification System receiver
hamexam - Study guide for USA FCC amateur radio (ham radio) license examinations.
hamfax - Qt based shortwave fax
inspectrum - tool for visualising captured radio signals
predict-gsat - Graphical Predict client
splat - analyze point-to-point terrestrial RF communication links
wwl - Calculates distance and azimuth between two Maidenhead locators
AX.25 – Packet Radio drivers for ax.25 protocol
linpac - terminal for packet radio with mail client
PyBOMBS - GNU Radio install management system
AMBEServer – AMBE vocoder chip support
HamClock – GUI HamClock by WBOEW
Adifmerg – command-line ADIF conversion utility
Lopora – QRSS Beacon Reception
Universal Ham Radio Remote (UHRR) – UHRR provides remote radio operation
RpiTx -- Turns Raspberry Pi into low power transmitter
ACARS Decoder – for tracking aircraft transponders
CygnusRFI – RFI analysis tool for ground stations and radio telescopes)
Update Scripts -- to update Fldigi suite and WSJT-X 
Radio Explorer - Displays shortwave radio broadcast schedules
OrssPiG - QRSSS (Raspberry) Pi Grabber
Minimodem - General purpose software audio FSK modem
Orca - Screen-reading software which supports blind hams
RBNC - Reverse Beacon Network Client
QDMR - a GUI application and command line tool to program DMR radios
wfview - a program to control modern Icom ham radios
DUDE-Star - RX/TX D-Star, DMR, Fusion YSF/FCS, NXDN, P25, M17, IAX (AllStar client)
Lady Heather - GPS Monitoring software
Cqrprop - Small application that displays propagation data from Paul, N0NBH website


Antenna Ham Radio Applications
===========================
antennavis - Antenna Visualization Software
Atlcl - Arbitrary Transmission Line Calculator
gsmc - A GTK Smith Chart Calculator for RF impedance matching
nec2c - Translation of the NEC2 FORTRAN source code to the C language
xnecview - NEC structure and gain pattern viewer
yagiuda - software to analyse performance of Yagi-Uda antennas


Digital Mode Ham Radio Applications
===============================
WSJT-X - Weak Signal (FT8, FT4, etc.) by W1JT
GridTracker - Graphical mapping companion program for WSJT-X or JTDX
JTDX - Alternate client for Weak Signal (FT8, FT4, etc.)
JS8Call - Messaging built on top of FT8 protocol by KN4CRD
JS8CallTools - Get Grid coordinates using GPS
(FLDigi is in its own section below.)
gnss-sdr - GLONASS satellite system Software Defined Receiver
linpsk - amateur radio PSK31/RTTY program via soundcard
multimon - multimon - program to decode radio transmissions
multimon-ng - digital radio transmission decoder
psk31lx - a terminal based ncurses program for psk31
twpsk - a psk program


Software Defined Radio
===================
CubicSDR - Software Defined Radio receiver
cutesdr - Simple demodulation and spectrum display program
GQRX - Software defined radio receiver
LeanSDR – Lightweight, portable software defined radio
SDR++ - Brand new cross-platform and open source SDR software
SDRAngel - SDR player
lysdr - Simple software-defined radio
SoapyAudio - Soapy SDR plugin for Audio devices
SoapyHackRF - SoapySDR HackRF module
SoapyMultiSDR - Multi-device support module for SoapySDR
SoapyNetSDR - Soapy SDR module for NetSDR protocol
SoapyRemote - Use any Soapy SDR remotely
SoapyRTLSDR - Soapy SDR module for RTL SDR USB dongle
SoapySDR - Vendor and platform neutral SDR support library
SoapySDRPlay3 - Soapy SDR module for SDRPlay3 API
Support for RTL-SDR
Support for SDRPlay SDR
Support for HackRF SDR
Support for AirSpy and AirSpy HF
SoapySDRAirSpy- Soapy SDR module for AirSpy SDR
SoapySDRFUNcube Dongle Pro+- Soapy SDR module for FUNCube Dongle Pro+
SoapySDRPlutoSDR- Soapy SDR module for Pluto SDR
SoapySDROsmoSDR- Soapy SDR module for Osmo SDR
SoapySDRRedPitaya- Soapy SDR module for Red Pitaya SDR
SoapyUHD- Soapy SDR module for Ettus ResearchUHD SDR
SoapySDRVOLKConverters - Support for VOLK-based type converters


APRS Applications
================
Xastir - APRS GUI client / Digipeater / Igate
YAAC - Yet Another APRS Client
DireWolf - Software "soundcard" AX.25 packet modem/TNC and APRS encoder/decoder
aprsdigi - digipeater for APRS
aprx - APRS Digipeater and iGate
soundmodem - Sound Card Amateur Packet Radio Modems


FLDigi Application Suite from W1HKJ
===============================
flrig - Rig Control program which interfaces with fldigi
fldigi - Digital Modes Communications
flaa - RigExpert Antenna Analyzer Control Program
flamp - File transmissions via Amateur Multicast Protocol
flarq - ARQ data transfer utility for fldigi
flcluster - Telnet client to remote DX Cluster Servers
fllog - Logbook application which can use same data file as fldigi
flmsg - Editor for ICS 213 Forms
flnet - Net Control Assistant for Net Activities (Check-In Application)
flpost - NBEMs post office
flwrap - File encapsulation and compression for transmission over amateur radio
flwkey - Winkeyer (or clone) control program for K1EL Winkeyer series


Logging Applications
==================
10 10 QSO Logger - Logging software for Ten Ten International Users
TrustedQSL - LotW client
CQRlog - Ham Radio Logging Application
PyQSO - Logging software (written in Python)
klog - The Ham Radio Logging program
tlf - console based ham radio contest logger
tucnak2 - VHF/UHF/SHF Hamradio contest log version 2
twlog - basic logging program for ham radio
upload_adif_log – Upload only new log entries to LotW, eQSL.cc and ClubLog
wsjtx_to_n3fjp - Logging adapter to allow WSJT-X to log to N3FJP
xlog - GTK+ Logging program for Hamradio Operators


WinLink Applications
==================
Pat WinLink - WinLink for Raspberry Pi (and other platforms)
ARDOP support for Pat WinLink
ARDOP-GUI - Provides graphical representation of ARDOP connections
Find ARDOP - Retrieves local ARDOP sources by KM4ACK
Pat Menu 2 – Menu for Pat by KM4ACK
PMON - a PACTOR® Monitoring Utility for Linux


Morse Code Applications
=====================
aldo - Morse code training program
cw - sound characters as Morse code on the soundcard or console speaker
cwcp - Text based Morse tutor program
xcwcp - Graphical Morse tutor program
cwdaemon - morse daemon for the serial or parallel port
ebook2cw - convert ebooks to Morse MP3s/OGGs
ebook2cwgui - GUI for ebook2cw
morse - training program about morse-code for aspiring radio hams
morse2ascii - tool for decoding the morse codes from a PCM WAV file
morsegen - convert file to ASCII morse code
qrq - High speed Morse telegraphy trainer
xdemorse - decode Morse signals to text
๐Ÿ˜ฒ

Just how amazing is that?? 

I struggled with the download a few times and I think it may have been that I was trying to download it straight to my 64Gb USB Stick, because after 4 failed attempts (even though there was PLENTY of space available on the stick) I tried to download straight to my C-Drive and it worked no problem.

Once you've got the image saved somewhere, you have the task of copying it over to an SD Card, which is extremely simple. A 16Gb should more than suffice but I used a 32Gb for future-proofing (it was only £3 more than a 16Gb card)...
  

Download a copy of Balena Etcher and install it, then run the program to complete the image writing. It's very straightforward but takes about half an hour to write it and verify it.



Once it's all finished, simply insert the card into your Pi and it should boot up with all that HamPi loveliness!

I could have connected the Pi400 to my main PC monitor because it has dual input ports, but that would then stop me using the main PC again for other things, so I decided to get a little monitor specifically for the Pi. It made sense to purchase a "Touch" screen and I found one which has a built-in stand and has regular and micro HDMI connections (plus USB to power it). The thing to be wary of with cheap screens is the power-supplies which come with them because they're often very noisy. That's why I opted for a screen which takes its power from the Pi itself.




Once I've spent more time using the software suite, I'll report back to this post.

73, Tom, M7MCQ

SCREENSHOTS














Wednesday, 20 October 2021

HAMCLOCK

SUPERB & FREE HAMCLOCK

We all love a good clock in the shack don't we? I've looked at quite a few over the last couple of years and have been tempted by some rather silly banks of cheap clocks with labels on such as LONDON, TOKYO, NEW YORK, etc, etc. But none of them are actually much use.


The HamClock from ClearSkyInsitute on the other hand, IS useful and it's free! Well, it's free software that runs on a Raspberry Pi. So you need to have the following in order to build this clock...

  • A Raspberry Pi 3 (Model B+ will suffice, more memory the better)
     
  • A Pi power supply
     
  • A screen (from a 7" up to whatever size you wish)
     
  • An SD Card and Reader



Once you've got your gear together, simply go to the ClearSkyInstitute website, download the software and Guide, then spend some time watching one of the many installation-guides on YouTube.

Despite what people say, it is not a piece of cake to do if you're a complete newbie to these micro computers! Some of the instructions you'll find online are not 100% accurate and they sometimes make assumptions about your knowledge of the Raspberry Pi. Anyway, I fumbled my way through, so I guess that's some indication of the simplicity of the task. 

Your aim throughout the build, is to get the software running correctly (obviously), find the right resolution for the monitor you'll be using, configuring the settings of the clock once it is working, and then finally, making it automatically boot up and go full-screen.



I happened to have a spare 21" monitor hanging around, so I used that. I chose to use the 1600x960 resolution and it looks real good. In the settings, I inputted my CallSign, LON/LAT, DX Cluster address, etc, etc. The Pi is set to switch the screen on and off at certain times on certain days. 

Just reading through the online HamClock User Guide will give you a good idea of all the information that it can provide and help you to decide whether or not it's a worthwhile addition to your shack.

Personally, I love it!

73, Tom, M7MCQ.

Comment below...

AMAZON - GOODBYE!!

As far as I'm concerned, Amazon are done! I am officially banning them from my supplier list. It's been coming for a while now, but my most recent  purchase has sealed their fate. 

It's not one thing, it's quite a few. In years gone by, I applauded their range of products, their prices and their efficiency in getting the order on your doorstep quickly. Nowadays, it's absolutely terrible.

More and more often I'm finding that their prices are extremely uncompetitive and sometimes (where availability is an issue) they are actually asking for more than RRP!! One of the most recent examples of this was when I went to purchase a decent WebCam. I figured out which was the best one to meet my needs and soon discovered that although it was a very popular camera, no one had stock - except of course, Amazon.

No surprise there huh? But what did surprise me was the fact that they were charging £5 more than the actual manufacturer was asking on their website. I found similar example of this with other products across a range of hobbies that I have interest in.

Then there's the introduction of 3rd Party Resellers on Amazon; it's so easy to be fooled into thinking that you're buying from Amazon when in fact, you're buying from someone else. Someone who might not really give a damn good customer service. As far as I'm concerned, 3rd Party suppliers listing on Amazon should be marked very clearly as such instead of being in disguise.


And then there's the long distance 3rd Party sellers who (again) can give you the impression that you're buying from within your own country, but in fact post from some 5,000 miles away! Yes, you can be careful and discover the origin of the seller, but that's not the experience I want from an online reseller - I want to trust them to look after my interests and not to mislead.

And let's not even talk about some of the useless couriers that they now use ๐Ÿ˜ฒ

Slow Boat From China
 
And then there's the DISGUSTING WASTE that they're responsible for. I've seen some truly laughable parcels arrive at my home/business. Huge boxes containing tiny items. I'm not even remotely "green" but it still makes me shudder at the ecological damage that Amazon are responsible for.

And then there's all the other underhanded things that Amazon get up to. Well, it's the end for me. I will no longer buy from them. Not at home and not at work.




Saturday, 9 October 2021

BELKA DX SWL RECEIVER

AN AMAZING RADIO!!

The Belka DX is nothing short of spectacular - for its size! And for the money. Who else sells a high performance HF receiver that fits in your shirt pocket, works superbly from a tiny telescopic whip and can be found for £150? No one!

It's a Direct Conversion SDR made of 'discrete' components. The Frequency range is 1.5MHz-31MHz,  all modes including two AM modes and an excellent CW mode with a sharp 300Hz filter. Unlike other radios in my possession (including some modern sdr radios), the Belka DX tuning is extremely accurate!

The smart steel case provides good RF shielding and a solid foundation for the popular BNC socket. Adjacent to the antenna socket is a headphone jack and a micro-usb charging point for the internal 2200mAh Lipo. On the opposite end of the case is the tuning knob and a stereo jack for the IQ-Out.

 
Originally, I was going to order directly from the maker in Belarus (Alex Buevsky, EU1ME) because I couldn't find a second hand one anywhere, but an attempt at an International Bank Transfer failed, so it kinda put me off ordering new. I saved a search on eBay and it wasn't long before a used one turned up at a fraction of the new price.

I collected the radio from the Post Office Hub (I'd missed the delivery) and inside the box was the radio, a telescopic whip and that's it!! No leads, no instructions. The dimensions of this matchbox-size radio really strikes you (pardon the pun). It's tiny! But boy, it feels and looks great. It oozes quality despite being so cheap to purchase.

The first thing I did was stick the telescopic whip on it and switch it on. The device had been left on Shanon Volmet frequency 5.505 and the signal was amazingly loud and clear - and I was sat inside my car!! A good start. When I arrived home, I put the Belka DX next to my trusty old AOR AR3000A. Switching between the two on a shared antenna showed no difference (apart from the fact that the 3000 was ever so slightly off frequency (but she is 30yrs old)). 

The display (despite being small) is fantastically clear - it makes the AR3000A look terrible. You can choose to have it backlit or not and there is full adjustment for brightness and contrast. At the bottom of the screen is the signal strength meter which provides a reading in 'dBยตv/EMF' which is gobbledygook to me, but roughly converted means halfway along the scale is S9.



Tuning around using the external antenna showed that not only had the Belka DX got superb sensitivity, but it also coped perfectly well with big signals, showing almost no signs of overloading. This surprised me considering how good it was on the telescopic. The AR3000A for example, needs to be physically attenuated when connected to an outdoor antenna. Image rejection is over 70 dB, better than an Elecraft KX3 according to F6DFZ's measurements.

Speaking of attenuators, the Belka DX doesn't have one. And neither does it have a PreAmp. But what it does have (which I prefer) is an RF GAIN adjustment. Well actually, they call it a 'Sensitivity' slider. It's a very handy tool and something I use all the time to hear better (usually by turning it down slightly).

As you can see from the image below, the Belka is even smaller than a little RSP1A and it's absolutely dwarfed by my Tecsun ๐Ÿ˜‚


The Belka DX that I purchased included the optional loudspeaker. It's not very loud, but it's fine indoors or in a fairly quiet outdoor environment. You can, of course, attach an amplified external speaker if you so wish. Probably better to use earphones (use a stereo jack or you will damage the radio). Choosing earphones with a long length of wire will assist reception by acting as a counterpoise.

There is a 3rd party speaker option on the market, which includes a pair of neat folding legs which put the Belka at a good viewing angle on a table, but to me, this option just adds too much bulk and detracts from one of the radio's biggest attractions - its tiny size!

LS3PW - Optional 3rd-Party speaker bolt-on

The ergonomics of the Belka have been criticised by some, but honestly, there's nothing wrong. Without reading the manual, I was able to do everything I wanted and very quickly found 'hidden' menus/options. If you are used to modern radios, it will all come easy to you.

The radio has 32 memories and I used these to store the start-frequencies of all the HAM bands, before adding a few other favourites. It makes it so easy to get where you want to be. The VFO knob is the perfect size for the radio and it feels like it's going to last forever.

I can't wait to take this out with me and throw a length of wire into a tree. Having said that, I feel that the telescopic will be good enough on its own, especially if I'm outdoors in a slightly elevated location. 


Above you can see the Belka being used outside in the garden with a mini-tripod (it's just easier to handle the radio without an antenna attached) and a recorder plugged into the IQ out socket.

I ordered a 1M length of RG400 terminated in BNC sockets to use with the Belka for separating the antenna. You can get them on Amazon or Ebay (they're cheap as chips, so it's hardly worth making one up). The bracket that I use for mounting the antenna to the tripod is the Elecraft TX1


The BELKA DX is just an awesome bit of kit. I'd say it's more for the HAM fan than the traditional SWL fan, since it doesn't include LW or MW. That is a shame but the HF coverage, SSB and CW modes, filters, stability, frequency accuracy and overall performance make up for it.   I think everyone should have one of these. Just stick it in your pocket wherever you go.



 

BELKA-DX DSP TECHNICAL SPEC

-Frequency range 1.5MHz - 31MHz
-Modulation modes CW, SSB LSB,NFM,AM1 and ะะœ2 (pseudo-synchronous).ALL MODE
-Frquency step 10, 20, 50, 100 Hz; 1, 5, 10, 50 kHz.
-Adjstuble bandwith, low and high skirts 2-4kHz; 50 - 300Hz.
-CW mode bandwith ~300 Hz; Adjustable CW pitch 500-1kHz.
-Receiver front-end is optimised for using telescopic antenna (800mm) in the range 1.5 - 31MHz.
-IQ output for viewing panorama on a computer
-Signal strength indicator (S-meter).
-Adjustable receiver sensitivity.
-Image rejection ~70dB.
-Timeout timer (TOT).
-Battery level indicator.
-Dial lock state indicator.
-Mode (modulation type) indicator.
-32 memory locations.
-Built in audio power amplifier, designed to work with external loud speaker with impedance 4-8 ohm.
-Charge and supply from micro USB port 5V.
-Built in battery LiPo 2200 mA
-Current consumption - around 80mA. Power consumption - 0.25mW with headphones.
-Battery life - 24 hours when on headphones.
-Built-in speaker (Optional)

Mechanical data:

- Cabinet measures 84ั…50ั…20mm

Thanks for visiting the blog. Leave a message below.

73, Tom, M7MCQ.


17M DOUBLE BAZOOKA

NEW ANTENNA FOR 17M

Trying to get my 40-10M EFHW to work on 17M is like trying to fit a square peg into a round hole. Sure, with the right  ATU I can force a match, but most of my 10W would get wasted and result in very little chance of making a contact unless band conditions are exceptional (like they were last week when I got through to W1MBB - just under 7,000km) ๐Ÿ˜ฒ


I purchased the bazooka direct from the manufacturer - a small company called Wire Antennas - the same place I got my EFHW from. When it arrived, I was a little surprised to find that the case-lid had quite a few scratches on it. Other than that though, everything else looked of high quality and a replacement lid was posted to me as soon as I notified WA about the problem.

When I opened up the box to fit the new lid, I thought the treatment of the coax-braid was a little "scraggy" but despite its appearance, it seemed solid enough. Bear in mind that this thing is only 30-odd quid, so it's not fair to tear it apart. 


In the small garden at the back of my bungalow, I have an EndFed HalfWave (also from Wireless Antennas) and a half-size G5RV. I was going to take down the G5RV and put this Double Bazooka in its place, but in the end I decided to give myself an easy weekend by doing a trial-install in the attic instead.

The antenna is only around 26ft long, so it makes for an easy installation in most spaces. In a flat-top dipole configuration, you only have to find 13ft of space for each leg and if you put it in an inverted-vee, you need even less space!


This 1950's design antenna is 98% efficient and it's extremely broad banded, meaning that the VSWR remains pretty constant throughout the 17M band - typically less than 2:1 so no antenna tuner is required whether you work in the CW or the SSB portion. When the antenna arrives, the two looped ends are left loose so that you can erect it and make small adjustments to the length to get the VSWR perfect for the part of the band that you use the most. Once you're finished tuning it, simply tighten up the two clamps and away you go.


Connecting my NanoVNA-F analyser to the antenna revealed that I needed to make some adjustments to focus it on the top end of the band which is where I work almost exclusively. As advertised, the VSWR was under 2:1.

Back in the Shack, I connected the Bazooka to my trusty ICOM IC-705 and was slightly disappointed with the noise level but this is no doubt due to the location of the antenna rather than the antenna itself. Looks like I'll have to make the effort to put it outside after all.

Anyway, I tuned around and found some activity. It wasn't long before I was breaking in to QSOs. Signal reports weren't very good, but again, that's because of the loft location. 

So it's going to be needing another look-at when I get around to putting it outside. I'll update this post then.

73, Tom, M7MCQ.



Friday, 1 October 2021

DIAMOND RH770 MINI-REVIEW

 DIAMOND  RH770 2m/70cm Telescopic (BNC)

I've got all sorts of fixed-length and telescopic antennas lying around the place and it's got to the stage where I wanted something decent. It had to be relatively compact, offer some gain and be a quality item, built to last. In the end, I plumped for the RH-770 from Japanese manufacturer Diamond.

The RH-770 is a 10-section  2M/70cm  telescopic whip fitted with a BNC connector and it is my intention to use it with my ICOM IC-705 when out and about. The antenna can handle 20W, so it'll be fine with the 705's maximum of 10W. Extended length is 930mm and 225mm retracted. It weighs just 85g.

The RH-770 has upper and lower sections with a centre-loaded coil and comes in a pretty tough plastic carry-case. In theory it provides a gain of 3db on 2M and 5.5db on 70cm. That's not bad for a simple telescopic in my opinion. 

Although this is a quality item, it's clear that it's not really intended to sit atop of handheld transceiver! These things are far too vulnerable to accidents for that sort of operating environment. They're much better suited to more static operations such as SOTA or POTA where you're generally sat down and settled with your radio equipment and not moving around. Very long antennas on portable radios always puts strain on the solder-joint of the radio's PCB.

The RH770 isn't different to any other telescopic in that care is needed when extending and retracting. It's vitally important (for long life) that the operator exercise caution by not being over-zealous when pulling out the sections to the limit. It's even more important to retract the antenna by putting the thicker sections away first. Forgetting to do that may result in a breakage to the thinner sections of the antenna.

One of the first things I did with the RH770 is connect it to an antenna analyser to see how resonant it was at different lengths. For this I used my NanaVNA-F and mounted the RH770 on a small tripod.

 

 
The test started with the antenna fully extended on the UK Calling frequency of 145.500. The result was a solid performance - 1.1:1 VSWR. If you touch the antenna, the SWR actually drops, so maybe I'll try attaching a counterpoise wire.



Before I mention the UHF figures, I should point out that I'd been watching a YouTube Video about the RH770 where a guy was using the antenna on 70cm with the top section fully extended and the bottom section only out about 10mm ๐Ÿ˜ฎ

That seemed a bit daft to me, but I figured he knew what he was doing, so I tried the same and then told myself to stop being silly and leave the antenna fully extended on both bands. That was, after all, what it was designed for and the reason that it had a coil in the middle.

Needless to say, fully extended on 70cm (focused again on the UK Calling Frequency of 433.500) the antenna returned a VSWR figure of 1.2:1
 


Those figures are more than acceptable and I'll be testing out the 'real world' performance of the RH770 out in the field this weekend with the ICOM IC-705.

More soon.

73, Tom, M7MCQ.

Tuesday, 28 September 2021

SHACK SHUFFLE

When my shack gets into a bit of a mess (which is often), I start to lose interest in spending time in there. This was happening recently because I'd removed the big MB1 base station and it left everything looking untidy. The answer was to devote some time to getting my house in order.

The new FT-891 needed to be permanently setup and it was important to do a proper installation complete with the SignaLink USB to give me FT8 capability  and the RSP1A to give me a Panadapter and Waterfall.

The SignaLink was straightforward but fitting an RSP1A meant introducing another piece of hardware to isolate the RSP1A from the FT-891's transmissions. I achieved this isolation by placing a clever little device called an MFJ 1708B-SDR in the loop.

The unit works in two ways - one is by sensing RF and the other is by detecting a control signal from the FT891's PTT circuitry. The latter is the preferred method and it is achieved by purchasing a CAT cable which has an RCA Phono lead that is connected directly to the MFJ-1708B.


 
The “B” series offers better isolation, achieved by additional relay isolation, and is specified up to 450MHz. An internal hybrid splitter reduces the antenna loading effect and provides isolation between the rig’s input and the SDR input. A TX LED on the front panel provides visual confirmation of correct operation when the transmitter is keyed. The MFJ-1708B-SDR features 3 SO-239 connectors, the MFJ-1708B-SDR-S substitutes an SMA female connector for the SDR connection.


It was quite a bit of messing around reorganising the shack because there's no way to access the back of the radio equipment (it's all mounted on shelves in a tiny alcove), but it's all sorted now and it's good to have the flexibility of SDR UNO software.


I'd forgotten how good this software is. It integrates perfectly with the 891 and it obviously permits one to listen through the radio or through the computer speakers. A friend recommended installing OmniRig but I'd already got it running in the background from a previous installation - I just had to switch ini file to suit the 891.



I also took the opportunity of bringing the DVMEGA CAST into the shack. I now have LW, MW, HF, VHF, UHF, C4FM, DSTAR and DMR (plus everything the RSP1A receiver provides (which includes Airband and Marine, etc)). 

73, Tom, M7MCQ.