Homebrew 80m/40m SSB/CW Rig - Part 1: Thoughts and Ideas

Brief video looking at what I intend to build for the next rig. It will be a SSB/CW single conversion superhet for 80m and 40m.

[radman]

What an excellent channel. Thank you so much for your contributions to the community, Charlie.

[steverodgers]

Glad to see you back! I would like to share a concern with your choice of 9 MHz IF for a 40 Meter radio. The 9 MHz may prove difficult to filter out since it is only 1.7-1.8 MHz away from the top of the 40 Meter band. The BP and LP filter filter will have to be very sharp and of a high order to ensure adequate attenuation of the 9 MHz if component. For a single band radio on 40 Meters I have used 12.288 MHz, but for 80 and 20 Meters 12.288 Mhz poses similar issues and 9 MHz would be better.

[judythomas]

A work of constructional art !.
Are you using single or double sided copper clad board, spec please ?

[RAUK]

From personal experience the CW signal from Si5351 is OK-ish. However keying a low frequency oscillator (next to the MIC on your block diagram) gives much better results and is not much more difficult to implement. I also would like to note that using Si5351 for BFO inevitably creates a lot of spurious signals. In order to build spurs-free single IF superhet receiver one have to use a well-filtered analog BFO. Naturally choosing this path will not allow you switching BFO and VFO channels. Did you consider building a rig based on amplifiers described in "A Termination Insensitive Amplifier
for Bidirectional Transceivers" [PDF] by W7ZOI and K3NHI? This will also remove the loops which are not uncommon source of parasitic oscillations.

[brianharper]

I remember seeing somewhere a design for a variable bandwidth crystal filter, possibly using varicap diodes, but not sure.
Not sure how much you could vary the bandwidth but thought it would be a nice idea rather than having 2 if filters .

[antoniohenriques]

Hello Charlie!
It looks like the Atlas 210X design. You can make a electronic switch with 4 JFET.
Best 73

[theuniscronje]

Hi Charlie

How can i contact you?

Regards Theunis Cronje from South Africa

[MXFXUK]

Hi Charlie you could use pin diodes to switch the RF paths and control it from the Arduino and it cheaper than relays just an idea. Looks like it should be an interesting project.

[christopheriles]

Hi Charlie,
I'm getting my parts together to build my own trx. Do I need to install any libraries in to Arduino IDE which I've downloaded?
If so, which ones will I need please?
I like your videos, keep them coming!

[bfx]

Looking forward for the series! Did you thought about different kind of switches instead of relays? Means not mechanical.

[johncundiss]

Love the video's. Want more. You get that 4PDT honker relay out of an old FT-102? I am doing the 'relay swap' in one on the bench. Love the layout. I also use a piece of plywood for projects.

[rfdave]

Hello Charlie. So good to see you again. I am getting excited. With Fall and Winter approaching here in the northern hemisphere, I want to get back into the home brew. I enjoy watching your videos. Thank you.

[curtstacy]

That sounds like fun Charlie! I've been missing this. can't wait to follow along.

[technishn]

Nice to see some more project work. I found that playing around with crystal filters that the orientation of toroids in the L-match circuits (lowpass config) affected the out of band rejection. The toroids were almost 70mm apart. Using a common relay may restrict rejection. Still worth a try

[skylabby]

Thanks Charlie, can't wait.. have a good one 73s.

[christopheriles]

Nice video Charlie; I am going to follow with great interest!

[justinelliott]

Where do we find your arduino sketch for the VFO/bfo/carrier