{"id":57588,"date":"2023-08-27T08:12:09","date_gmt":"2023-08-27T12:12:09","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=57588"},"modified":"2023-08-27T08:12:09","modified_gmt":"2023-08-27T12:12:09","slug":"guest-post-switching-a-remote-antenna-low-noise-amplifier-and-an-antenna-and-audio-between-two-radios","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2023\/08\/guest-post-switching-a-remote-antenna-low-noise-amplifier-and-an-antenna-and-audio-between-two-radios\/","title":{"rendered":"Guest Post: Switching a Remote Antenna, Low Noise Amplifier, and an Antenna and Audio Between Two Radios"},"content":{"rendered":"

Many thanks to SWLing Post<\/em> contributor,\u00a0Bill Hemphill<\/a>, who shares the following guest post:<\/strong><\/p>\n

\n

Remote Antenna Switching <\/b>Remote Low Noise Amplifier Switching <\/b>and <\/b>Switching an Antenna and Audio Between Two Radios<\/b><\/h1>\n

by Bill Hemphill, WD9EQD<\/b><\/p>\n

Remote Antenna Switching<\/b><\/h2>\n

I have two YouLoop Antennas.\u00a0 I had been placing them at right angles to each other.\u00a0 I would then put one of them on the AirSpy software defined radio.\u00a0 But manually switching from one antenna to the other was a real pain.\u00a0 If only there were a way to electrically switch between the two antennas.<\/p>\n

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.\u00a0 It was research time.<\/p>\n

The YouLoop and the Airspy both use SMA connectors.\u00a0 An SMA switch would be required.\u00a0 A little research and I came across the following small board that can switch between two SMA antennas:<\/p>\n

\"\"<\/a>From Amazon Description:\u00a0 50 Ohms RF Switch Module, 3-<\/i>5V Remote Wireless RF Switch Single Pole Double Throw Board Input Output Impedance for DIY Electric Doors (HMC349)<\/i><\/a><\/p>\n

This board is perfect for RECEIVE only projects.\u00a0 Apply 5V to the board and then 5V to the VCC (control pin) to switch from RF1 to RF2.<\/p>\n

Now that I had the SMA switch module, a way to actually do the switch remotely was required.\u00a0 Maybe WI-Fi or Bluetooth module would do the trick.\u00a0 I found a nice Wi-Fi module on Amazon that looked like it would do the trick:<\/p>\n

\"\"<\/a>Amazon Description:\u00a0 DIYmalls SV Safe Low Voltage WiFi Wireless Switch Module DC 5V-24V Phone APP Remote Control Smart Home for Amazon Alexa Google Assistant<\/i><\/a><\/p>\n

But do I really want to use a phone app to switch antennas.\u00a0 Further investigation discovered a really neat module that uses a Car Fob type control:<\/p>\n

\"\"<\/a>Amazon Description:\u00a0 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<\/i><\/a><\/p>\n

BIngo!!\u00a0 I could just press a button and switch antennas.\u00a0 But a problem quickly arose.\u00a0 I hadn\u2019t fully read the description of the RODOT switch:<\/p>\n

The blue output wire is ALWAYS Vcc (input voltage)! The device only switches the ground.<\/i><\/b><\/p>\n

So the RODOT switches the ground but the HMC349 uses positive voltage to switch.\u00a0 OOPS.\u00a0 Next step was to place a latching relay to take the on\/off ground and convert it to on\/off positive.\u00a0 Again, another nice board was found:<\/p>\n

\"\"<\/a>Amazon Description:\u00a0 HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger<\/i><\/a><\/p>\n

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.<\/p>\n

All modules are powered by 5V.\u00a0 There are other modules available that use higher voltages.\u00a0 But I wanted to be able to use a 5V power source for everything.<\/p>\n

I learned a quick lesson on the first layout I did. I had directly connected the antenna cables to the HMC349 module.\u00a0 A quick accidental side yank on one of the antenna cables and the SMA connector tore off the board.\u00a0 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.<\/p>\n

I found a nice small plastic box that allowed for the HMC349 module to be suspended between SMA bulkhead connectors.\u00a0 By using bulkhead connectors, there is no strain placed on the HMC349 connectors. The relay module was attached to the box lid.\u00a0 The modules are mounted using brass standoffs.\u00a0 The finished box is about 3\u201dx4\u201dx 2\u201d high.\u00a0 Either battery or a 5V wall module can be used to power it.<\/p>\n

\"\"<\/a>\"\"<\/a>Overall, I\u2019m quite pleased with the results.\u00a0 I find that sometimes switching antennas (and their orientation) can make a big improvement in the signals.\u00a0 Other times, there\u2019s very little difference.<\/p>\n

Remote Low Noise Amplifier along with Antenna Switching<\/b><\/h2>\n

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.\u00a0 Something like the Lana HF Barebones LNA made by NooElec<\/a>:<\/p>\n

\"\"<\/a>For testing purposes, I first did a quick layout of just using one antenna with the ability to switch the LNA in and out.\u00a0 Note:\u00a0 I took a gamble on hooking the antenna cables directly to the HMC349 modules.\u00a0 Luckily, the SMA connects didn\u2019t tear off the boards.<\/p>\n

\"\"<\/a>Two HMC349 modules are used.\u00a0 The first module selects the bypass or the LNA.\u00a0 Likewise, the second module also selects either the bypass or LNA.\u00a0 Note that the second module is turned upside down so that the switches match up when activated.\u00a0 Two modules were used so that the LNA is totally switched out of the circuit. <\/p>\n

One part was still bugging me \u2013 that was the need to use that external relay to account for the fact the remote module switched the common and not the hot.\u00a0 A little more research and a combination relay\/remote module was located:<\/p>\n

\"\"<\/a>Amazon Description:\u00a0 DieseRC Wireless Remote Control Switch 433Mhz 5V 12V 24V 1 Channel Radio Control Relay Receiver with 2 Transmitters keyfobs Potential-Free Contacts Relay Controller<\/i><\/a><\/p>\n

By using this, the circuit was cleaned up a little bit.<\/p>\n

The ultimate goal was to have a box that two antennas would be connected to and then pressing the first button on the remote, an antenna would be selected.\u00a0 The second button would then switch the LNA in and out of the circuit.<\/p>\n

I found a nice plastic box that had a mounting plate in it where all the components could be mounted to<\/a>.<\/p>\n

I first laid out the components to determine spacing, etc.:<\/p>\n

\"\"<\/a>There are two Remote Relay boards and three HMC349 SMA switch modules.\u00a0 At the top is a board used for providing power to all the boards.<\/p>\n

Components get mounted to the base board using brass standoffs.<\/p>\n

\"\"<\/a>Testing the exact spacing for the HMC349 boards and the connections to the bulkhead SMA\u2019s:<\/p>\n

\"\"<\/a>Final wiring (I know \u2013 it\u2019s messy, but it works):<\/p>\n

\"\"<\/a>Short pieces of SMA cable is used to connect the LNA to the HMC349 modules.<\/p>\n

The antenna switch described earlier and the Antenna & LNA switch side by side:<\/p>\n

\"\"<\/a>Switching an Antenna and Audio Between Two Radios<\/b><\/h3>\n

I\u2019m always fascinated when someone does a test between Radio A and Radio B.\u00a0 An attempt is made to use similar antennas, similar audio setting and then the same radio station.\u00a0 This got me to thinking that wouldn\u2019t it be nice to be able to switch an antenna between two radio and at the same time switch the audio out from the radio.\u00a0 Thus, only the audio from the radio connected to the antenna would be heard.\u00a0 This would allow for instant comparison.\u00a0 The finished box would have a connection for the antenna, two connections out to go to the two radios.\u00a0 It would also have two 1\/8\u201d audio jacks in that come from the radios and a 1\/8\u201d audio jack out.\u00a0 Pressing the button on the remote would switch the antenna from Radio A to Radio B and at the same time switch the audio out so that only the audio from the selected radio is heard.\u00a0 Pressing the button on the remote again would reverse the radios.<\/p>\n

Two relays were used to totally isolate the audio.\u00a0 Only mono audio is used.\u00a0 One relay switches the audio ground and the other relay switches the audio.\u00a0 Not sure if the audio ground really needed switching or not.\u00a0 Just wanted to ensure that audio didn\u2019t bleed from one radio to the other.<\/p>\n

\"\"<\/a>One SMA for the antenna and two SMA\u2019s to go to the two radios:<\/p>\n

\"image16\" <\/a> <\/div> <\/div>
\"image17\" <\/a> <\/div> <\/div> <\/div> <\/div>\n

1\/8\u201d audio jacks:<\/p>\n

\"\"<\/a>Note that the Radio\/Audio switcher can be daisy chained with the LNA\/Antenna switching box.\u00a0 This would allow for selecting Antenna A or B, with or without LNA and Radio A or B.<\/p>\n

Still To-Do is to add LED\u2019s so that I can visually tell which Radio and Audio is selected.<\/p>\n

Conclusion<\/b><\/h2>\n

I\u2019ve had a lot fun making these.\u00a0 It brought back a lot of memories of when I was a kid and would build things.\u00a0 It\u2019s really neat that there are all sorts of small modules that can be purchased for very reasonable prices.\u00a0 These modules almost allow for plug and play.\u00a0 Just need a little bit of interfacing to make all sorts of interesting projects.<\/p>\n

Please note: All Amazon links are affiliate links and support the SWLing Post at no cost to you.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Many thanks to SWLing Post contributor,\u00a0Bill 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.\u00a0 I had been placing them at right angles to each other.\u00a0 I would […]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[3607,3194,627,3,43],"tags":[4890,1643,6954,10312,10310,10311],"class_list":["post-57588","post","type-post","status-publish","format-standard","hentry","category-antennas","category-guest-posts","category-how-to","category-news","category-shortwave-radio","tag-antenna-projects","tag-antennas","tag-bill-hemphill-wd9eqd","tag-how-to-make-a-remote-antenna-switch","tag-how-to-make-audio-switch","tag-how-to-make-switchable-low-noise-amplifier"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-eYQ","jetpack-related-posts":[{"id":18772,"url":"https:\/\/swling.com\/blog\/2016\/07\/the-aaa-1c-an-affordable-loop-antenna-amplifier-kit\/","url_meta":{"origin":57588,"position":0},"title":"The AAA-1C: An affordable loop antenna amplifier kit","author":"Thomas","date":"July 19, 2016","format":false,"excerpt":"I recently stumbled upon the\u00a0Active Antenna Amplifier (model AAA-1C) by LZ1AQ. At 87.00 EUR, it's a pretty affordable and flexible solution for those who would like to design or use a loop antenna. According to the website, it packs a lot of features: 4 remotely switched modes (Loop A, Loop\u2026","rel":"","context":"In "Antennas"","block_context":{"text":"Antennas","link":"https:\/\/swling.com\/blog\/category\/antennas\/"},"img":{"alt_text":"Active-Antenna-the-kit-product-7","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/05\/Active-Antenna-the-kit-product-7.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/05\/Active-Antenna-the-kit-product-7.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/05\/Active-Antenna-the-kit-product-7.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":43930,"url":"https:\/\/swling.com\/blog\/2020\/06\/bills-first-dx-contest-using-a-panasonic-rf-2200-and-a-hombrew-diode-loop-radio\/","url_meta":{"origin":57588,"position":1},"title":"Bill’s first DX contest using a Panasonic RF-2200 and a hombrew diode\/loop radio","author":"Thomas","date":"June 19, 2020","format":false,"excerpt":"Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who shares the following guest post: My First DX Contest by Bill Hemphill, WD9EQD Being a recent new member of NJARC, this is my first time competing in this contest.\u00a0 I have always been a big fan of BCB DXing and\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/06\/NJARC-Contest-Logs-Bill-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/06\/NJARC-Contest-Logs-Bill-1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/06\/NJARC-Contest-Logs-Bill-1.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/06\/NJARC-Contest-Logs-Bill-1.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":51178,"url":"https:\/\/swling.com\/blog\/2021\/12\/airspy-hf-discovery-shortwave-portables-having-fun-with-the-airspy-youloop\/","url_meta":{"origin":57588,"position":2},"title":"Airspy HF+ Discovery & Shortwave Portables: Having Fun with the Airspy YouLoop!","author":"Thomas","date":"December 14, 2021","format":false,"excerpt":"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.\u00a0 While I have strung up some hidden outdoor wire antennas, I have found that they didn\u2019t really perform that\u2026","rel":"","context":"In "Antennas"","block_context":{"text":"Antennas","link":"https:\/\/swling.com\/blog\/category\/antennas\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/12\/Screen-Shot-2021-12-14-at-06.15.01.png?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/12\/Screen-Shot-2021-12-14-at-06.15.01.png?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2021\/12\/Screen-Shot-2021-12-14-at-06.15.01.png?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":33579,"url":"https:\/\/swling.com\/blog\/2018\/08\/bill-tweaks-his-am-loop-antenna-for-optimal-mediumwave-performance\/","url_meta":{"origin":57588,"position":3},"title":"Bill tweaks his AM loop antenna for optimal mediumwave performance","author":"Thomas","date":"August 17, 2018","format":false,"excerpt":"Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who writes with the following update to his previous post: As you may remember, back in May, I picked up a beautiful home-made loop antenna. It was 25 inches on a side with 23 turns of wire. My initial testing showed\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/08\/loop-calculator-2.png?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/08\/loop-calculator-2.png?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/08\/loop-calculator-2.png?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":43124,"url":"https:\/\/swling.com\/blog\/2020\/05\/panasonic-rd-9820-antenna-coupler-operating-instructions\/","url_meta":{"origin":57588,"position":4},"title":"Panasonic RD-9820 Antenna Coupler Operating Instructions","author":"Thomas","date":"May 3, 2020","format":false,"excerpt":"Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who shares a PDF copy of the Panasonic RD-9820 Antenna Coupler we recently mentioned in a post. He notes that he can't remember how he found this manual, but thought he'd share it. Click here to download the RD-9820 manual as\u2026","rel":"","context":"In "Accessories"","block_context":{"text":"Accessories","link":"https:\/\/swling.com\/blog\/category\/accessories\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/04\/RF-2200-Antenna-Coupler-1024x848.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/04\/RF-2200-Antenna-Coupler-1024x848.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/04\/RF-2200-Antenna-Coupler-1024x848.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":31920,"url":"https:\/\/swling.com\/blog\/2018\/05\/bill-scores-a-homebrew-lw-mw-magnetic-loop-antenna\/","url_meta":{"origin":57588,"position":5},"title":"Bill scores a homebrew LW\/MW magnetic loop antenna","author":"Thomas","date":"May 7, 2018","format":false,"excerpt":"Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD) who shares the following: I went to the Warminster Amateur Radio Club (WARC) hamfest [yesterday] in Bucks County, PA. For some time, I have been thinking about making a loop antenna for AM DXing. It was my lucky day. When I\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/Mag-Loop-Antenna-Homebrew-1-777x1024.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/Mag-Loop-Antenna-Homebrew-1-777x1024.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/Mag-Loop-Antenna-Homebrew-1-777x1024.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/57588","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/comments?post=57588"}],"version-history":[{"count":6,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/57588\/revisions"}],"predecessor-version":[{"id":57640,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/57588\/revisions\/57640"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=57588"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=57588"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=57588"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}