Re: Homebrew SSB Transceiver
 

Not seen that one before. I’ve only built two MOSFET PA however as they were cheaper than a decent RF PA transistor.

Re: Homebrew SSB Transceiver
 

Looks like it's in class A to me. Does it still get hot with no drive? What's the emitter voltage with no RF drive? From that you can get the collector current and from that the dissipation.

Re: Homebrew SSB Transceiver
 

I will adjust the bias on sunday to see if the output is affected, and .... Andrerw.. I will check that....If it was true class "A" surely the waveform should be equal and not clipped on the bottom half.

Re: Homebrew SSB Transceiver
 

Lesson learned.......... while putting the "finishing" touches to the project.. an odd thing started to happen.... when going to transmit.... sometimes I would get drive.. and sometimes not.... if the radio was powered off and back on.. it would give RF out.. but cycling TX/RX a few times then the drive would disappear until I powered off etc...
At first I blamed one of the relays sticking on..... but no, .... if the TX was activated WITHOUT the DC to the PA... however many times it was switched it worked 100%.
I put a "T" junction at the output of the DDS source and found that the RF from the DDS oscillator was shifting from I.F + carrier = 12.37 to 3.15 Mhz........ ??????
Obviously something was corrupting the micro controller..
No I wont leave it there...............I fitted a RF snubber network across the TX DC relay contacts .. 100R + 100nF PROBLEM Solved.....obviously the rf energy in the contact spark was corrupting the PIC controller.. not an obvious .... well to me anyway.. symptom and cure.
Onward and upward. NEXT !!!!!

Re: Homebrew SSB Transceiver
 

Good find! It's always the computer half that lets it down.

Some progress to report on mine finally. First two tone test through the transmit chain up to the driver that didn't cause smoke to come out somewhere! BFO balanced modulator needs some work as the balance is slightly poor. Will do PA integration in the next week. Then it's back to the receive chain.

Attachment 181681

Re: Homebrew SSB Transceiver
 

Hi Mr "B"..I didnt realise you were on a similar path. Up to now my micro controller modules have worked perfectly..so I was surprised when it "fell over". My friend in Oz wrote some good software. I suppose its not surprising when contacts switching 40 watts ish are not damped.
Your two tone waveform looks good to me.. if you pvt me I can send you my PDF's of up to now progress.

Re: Homebrew SSB Transceiver
 

Last posting on this project... unless anyone has any queries..The outer case is a reclaimed Heathkit RA1 receiver...

NEXT !!!

Re: Homebrew SSB Transceiver
 

Thanks for posting pictures. Looks really good. Sorry I haven’t got back to you regarding last message yet - unfortunately had a minor accident so out of action now for a week or so. Would be interested in your PDFs.

Re: Homebrew SSB Transceiver
 

Final final post with case on..unless someone wants more info.

Re: Homebrew SSB Transceiver
 

Very nice work. I still haven’t got around to emailing you yet! I will get there.

Re: Homebrew SSB Transceiver
 

Lovely job, to my eye the decimal point on the display is too high (fantastically small niggle and it's not mine to complain about)

Re: Homebrew SSB Transceiver
 

Sorry Merlin.. I did not make the LCD Display.. otherwise I would have changed it just for you .LOL

Re: Homebrew SSB Transceiver
 

Looks really good! Have you made any contacts with it yet?

Re: Homebrew SSB Transceiver
 

Hi Jeremy..... As you ask.... no.. I have put out a few CQ Test calls... but as yet no... tried 80 and 40.... I know RF is getting out as the lamp in my bedroom comes on at number 1 "electronic touch " switch... and I know the mod is ok...but maybe the stations I am hearing are putting a bit more power than me......
I was out at Blackpool today.. so monday morning I will re try... trouble is.. my half 5RV is not suited to 80 m although the KW tuner is peaking ok.
To pass the time.. I re jigged my Watson SWR /Power meter... adding an RF sniffer for the spectrum analyser.... and fixing a 100W dummy load on top.. and an RF switch on the side.... I like things tidy.

Re: Homebrew SSB Transceiver
 

Hello. Wendy.
I have to take my hat off to you Outstanding work and looks professional .

Kevin.:thumbsup:

Re: Homebrew SSB Transceiver
 

Thanks Kevin and others that have commented.... I am fortunate to have the time.."single" and retired with no constraints. I have built "stuff" since my apprenticeship days...but only recently have made things I would like to see. I was at the NARSA at Blackpool yesterday.. mooching..getting the "odd" bit for the next possibility. The front panel of the transceiver was bigger than A4, so I had to go to the print shop..great service, only £3 for two copies on card. then covered with clear acetate from the artshop.
I made the knobs on the lathe as I didnt like any of the commercial ones.