• Your 2020 builds!

Posted: **Tue Mar 16, 2021 9:21 pm**

Zozo wrote: ↑Sat Feb 27, 2021 2:06 pm MF & HF Valve AM/CW Transmitter. Built Last year as my lockdown project. Modulation is "Clamp Tube / Controlled Carrier". Can operate from Medium Wave all the way to the top of the HF Band simply by changing the XTAL and the Output Pi Coil.

Front:
20210227_135539.jpg

Back:
20210227_135606.jpg

Top:
20210227_135545.jpg

Home Made Plug-in Pi Coils:
20210227_135623.jpg

Zozo some nice MF/HF stuff there!

Posted: **Tue Mar 16, 2021 9:37 pm**

Well not really a 2020 build, but started getting the bits together and working out where stuff was going to be place. Only finished this off last week.

Another shortwave transmitter "The Commando" Sounds alot better and produces about 25watts.

Posted: **Tue Mar 16, 2021 9:38 pm**

Gigahertz wrote: ↑Tue Mar 16, 2021 9:21 pm
Zozo some nice MF/HF stuff there!

Thanks Gigahertz, I'll make a little video of me loading it up and feeding in some audio. Currently working on another project at the moment, so when the bench is free I'll get round to it.

Maybe even post the schematic if people are interested. It's not drawn up and resides solo in my head a present.

Posted: **Tue Mar 16, 2021 9:40 pm**

Gigahertz wrote: ↑Tue Mar 16, 2021 9:37 pm Well not really a 2020 build, but started getting the bits together and working out where stuff was going to be place. Only finished this off last week.

Another shortwave transmitter "The Commando" Sounds alot better and produces about 25watts.

Nice work Gigahertz, I see we both like to use FT243 Xtals

Posted: **Tue Mar 16, 2021 9:41 pm**

Few more pics

Posted: **Tue Mar 16, 2021 9:43 pm**

Zozo wrote: ↑Tue Mar 16, 2021 9:40 pm
Gigahertz wrote: ↑Tue Mar 16, 2021 9:37 pm Well not really a 2020 build, but started getting the bits together and working out where stuff was going to be place. Only finished this off last week.

Another shortwave transmitter "The Commando" Sounds alot better and produces about 25watts.
Nice work Gigahertz, I see we both like to use FT243 Xtals

Thanks Zozo

I was struggling to find FT-243 Xtals but I have a few options now I got some from the States

Posted: **Tue Mar 16, 2021 9:51 pm**

I know a guy in the states too. But I've have a few FT-243's that I've stripped down and put HC-49s inside. I don't mind spending out for new Xtals from QuartzLab

All noted on the frequency 6210 Khz. I'll keep an ear out for you. What's your choice when it comes to antenna's on 49/48m bands? I do like the EFW in Inverted L configuration.

Posted: **Tue Mar 16, 2021 10:02 pm**

Zozo wrote: ↑Tue Mar 16, 2021 9:51 pm I know a guy in the states too. But I've have a few FT-243's that I've stripped down and put HC-49s inside. I don't mind spending out for new Xtals from QuartzLab

Hmmmm that's instresting know

Looking at the SW section I think 6210KHz will be too close to "LHH" so will see what else I've got.

Antenna wise not 100% but EFHW could be a good idea just got to find a decent place to set it up first. What Toroidal type you using to make the matching unit?

Posted: **Tue Mar 16, 2021 10:21 pm**

Gigahertz wrote: ↑Tue Mar 16, 2021 10:02 pm
Zozo wrote: ↑Tue Mar 16, 2021 9:51 pm I know a guy in the states too. But I've have a few FT-243's that I've stripped down and put HC-49s inside. I don't mind spending out for new Xtals from QuartzLab
Hmmmm that's instresting know

Looking at the SW section I think 6210KHz will be too close to "LHH" so will see what else I've got.

Antenna wise not 100% but EFHW could be a good idea just got to find a decent place to set it up first. What Toroidal type you using to make the matching unit?

I've hit the Twente WebSDR on a horizontal EFW, which was pretty much "NVIS" the height I had it off the ground with just 5watts carrier.

Yes LHH might be a bit close to that frequency you've got. But I think they are off on 6205 at the moment, due to antenna issues from last week.

For the inverted L, I like to use the L Match network for solid state gear. Just a simple variable capacitor with about 500pf and close wound wire coil on PVC former with tapping points. The coil's "Q Factor" will be much better with minimal losses, when compared to toroidal's in transformer-matching configurations, like the 69:1, 49:1 etc.

The L Match Network

0d1f263e2bf7e684a9733473e0084720.jpg

Posted: **Tue Mar 16, 2021 10:26 pm**

My last project

Handy frequency counter based on Attiny44 and sanyo LB3500 prescaler. Measure range from 30 to 150 MHz according to LB3500 DS, but it works on higher frequencies too. It has very good sensitivity - 2 turns coil can be connected to input and measurment can be done indirectly. The total divide is 32 - 8 by LB, and 4 by LS293. Gating time 500ms. I supply it via USB without any measurement disturbances. Fusebits : CLKDIV8 "off" and "External crystal > 8MHz"

IMG_20210311_214222273_c.jpg

IMG_20210311_214254544_c.jpg

IMG_20210311_215844177_c.jpg

IMG_20210316_214442865_c.jpg

schematic.png

freq.zip

Posted: **Tue Mar 16, 2021 10:39 pm**

1608cc wrote: ↑Tue Mar 16, 2021 10:26 pm My last project Handy frequency counter based on Attiny44 and sanyo LB3500 prescaler. Measure range from 30 to 150 MHz according to LB3500 DS, but it works on higher frequencies too. It has very good sensitivity - 2 turns coil can be connected to input and measurment can be done indirectly. The total divide is 32 - 8 by LB, and 4 by LS293. Gating time 500ms. I supply it via USB without any measurement disturbances. Fusebits : CLKDIV8 "off" and "External crystal > 8MHz"

freq.zip

Great work 1608cc, It's gone together really well. Also it's really nice you have even shared the schematic and what looks like the required HEX File into a ZIP file for everyone to download.

I see you've put a fixed whip antenna on the end. I probably may have gone for a BNC connector to allow in to be connected to a directional coupler etc, or a rubber duck antenna for RF sniffing when portable.

. But that's just something I might have done.

Posted: **Tue Mar 16, 2021 10:42 pm**

Gigahertz wrote: ↑Tue Mar 16, 2021 10:02 pm
Zozo wrote: ↑Tue Mar 16, 2021 9:51 pm I know a guy in the states too. But I've have a few FT-243's that I've stripped down and put HC-49s inside. I don't mind spending out for new Xtals from QuartzLab
Hmmmm that's instresting know

Looking at the SW section I think 6210KHz will be too close to "LHH" so will see what else I've got.

Antenna wise not 100% but EFHW could be a good idea just got to find a decent place to set it up first. What Toroidal type you using to make the matching unit?

HC-49 inside a FT 243 housing

20210316_222541.jpg

Posted: **Tue Mar 16, 2021 10:52 pm**

The completed LPAM Medium Wave transmitter. Front panel took a bit longer than I hoped, but I finally got there.

20210312_115458 (1).jpg

Posted: **Wed Mar 17, 2021 3:53 pm**

Zozo wrote: ↑Tue Mar 16, 2021 10:39 pm Great work 1608cc, It's gone together really well. Also it's really nice you have even shared the schematic and what looks like the required HEX File into a ZIP file for everyone to download.

I see you've put a fixed whip antenna on the end. I probably may have gone for a BNC connector to allow in to be connected to a directional coupler etc, or a rubber duck antenna for RF sniffing when portable. . But that's just something I might have done.

There wasn't space for BNC conn in my case - I found nice plastic housing which perfectly fitted to dimensions of PCB. I used needle soldered to input pad

- ideal for "time to time" measurements, without any additional cables etc. - just touch and you get a reading.

Posted: **Tue Mar 30, 2021 12:35 pm**

Here's another lockdown project, a synthesised Band-I link RX. It's more than sensitive enough for Band-I given the high noise levels in the band. I didn't bother with a low noise pre-amp - it's pretty pointless when the noise levels are well over 6dB above thermal. It puts in good audio performance too. The blue LED shows the synth is locked, and the red/yellow/green form a basic signal level meter. The green LED also feeds a buffered output which can be used to drive a relay for remote TX switching. It will work anywhere in Band-I (with suitable coils fitted) and could even be pushed into Band-III, with maybe a small loss of sensitivity.

Rev

IMG_20210329_195134.jpg

Posted: **Tue Mar 30, 2021 12:41 pm**

Gigahertz wrote: ↑Tue Mar 16, 2021 9:43 pmI was struggling to find FT-243 Xtals but I have a few options now I got some from the States

I've got a couple of FT-243 xtals on relatively useful frequencies (6916 and 6975 kHz). PM me if interested.

I've also got some xtals in other cases (i.e. HC-6U/HC-18U) on various other HF frequencies.

Rev

Posted: **Tue Mar 30, 2021 1:19 pm**

reverend wrote: ↑Tue Mar 30, 2021 12:35 pm Here's another lockdown project, a synthesised Band-I link RX. It's more than sensitive enough for Band-I given the high noise levels in the band. I didn't bother with a low noise pre-amp - it's pretty pointless when the noise levels are well over 6dB above thermal. It puts in good audio performance too. The blue LED shows the synth is locked, and the red/yellow/green form a basic signal level meter. The green LED also feeds a buffered output which can be used to drive a relay for remote TX switching. It will work anywhere in Band-I (with suitable coils fitted) and could even be pushed into Band-III, with maybe a small loss of sensitivity.

Rev

IMG_20210329_195134.jpg

Looks good Rev, It's a fully featured board by the sounds of things. Nice touch with relay control option for "Carrier Access" for people who like to still have that option. I can't see what your using for the synthesizer, picture not that clear to read.

Posted: **Tue Mar 30, 2021 4:35 pm**

Zozo wrote: ↑Tue Mar 30, 2021 1:19 pmLooks good Rev, It's a fully featured board by the sounds of things. Nice touch with relay control option for "Carrier Access" for people who like to still have that option. I can't see what your using for the synthesizer, picture not that clear to read.

Thanks ZoZo. The synth chip is the age old MC145152 - I have a bucket load of these hanging around otherwise I'd be using one of the more modern synth chips and a PIC!

Rev

Posted: **Tue Mar 30, 2021 4:48 pm**

Hi reverend, will you be posting this up eventually ? I want to try building a band 1 rx.

Posted: **Tue Mar 30, 2021 10:35 pm**

Excellent work Reverend!

Did you need to use some kind of divider for the local oscillator frequency to feed the PLL?

Your 2020 builds!

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