开云体育

Hello everyone,

This is my inaugural post here in the QRP-Tech group. I have done a lot of hacking on the BITX40, and feel that i understand it fairly well. I also have homebrewed a DC receiver. I've written about that all on my blog in case anyone cares to read it, .

I followed the digital DSB thread with great interest, and if you read my site you'll see I've written on the subject. Part of the discussion that piqued my interest was a post in which it was explained how a simple SSB transceiver could be built using phasing. I don't fully understand phasing (the math in EMFRD is waaaay over my head) but it looks like if one does the math right (using online calculators?) it would be simple enough to design and construct.

And thus my question emerges. I don't own a scope although if intend to eventually. But lets say I don't, and I want to homebrew the simplest SSB transceiver design: A direct conversion receiver with a phasing filter to the audio amp, with the same filter used in reverse to strip the sideband going to the PA. Allison (Who I am hoping will shed some light on this subject!) mentioned it would be pretty simple, which I understand to be a very relative term :p

What designs exist, and could they be built without a scope? That is my question.
--
Ryan Flowers W7RLF

QRP Labs has a QSD receiver and a phasing module to go with it.

Once you understand how the phasing SSB Rx works you might be able to figure
out how to do a phasing QSE.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"

Simple, a scope is over used. Often not required or at best a handy tool.

I build mine using mostly my ears and a good DMM.

If you have EMRFD the miniR2 design is pretty much precooked and a
just build it. the R2pro is also same thing just build to a higher performance.
The math is if you want to do ground up or understand the reason it works.
generally its good to read the text around it as it explains whats going on
without the hoary math. The QST published a bunch of years back
MicroR2 as a good RX and they had a matching TX. I've built both on
a board and dead bug.

The KK7B are my prefered designs but I'vebuilt some of the minimal and
lower performing designs and found they were quite adequate.

There are others is the RSGB compendiums and a few old school designs but
generally they are fussier to build. The key is if they want 1% parts (resistors)
do it. Same for caps.

The tool I found most handy was the AADE LCII or similar. The few critical
inductances and caps were easily matched or checked.

As to tune-up. A signal on the air and tune across it if the other sideband
is no existent (cant be found or ever very weak compared to the desired one)
its good. If things are done (adjusted) right you can tell.

IT depends on if you into CW or SSB as the Dan Tayloe designs for CW
were also good. Also CW only needs the Good RX and if your doing SSB
the TX is really just the RX with all the paths going the other way.

Allison
--
Please reply on the group, no private emails we as a group get to share info that way.

FYI the QCX receiver is a image rejecting design (phasing) for SSB changing a
few resistors in the audio filter (from CW band width to SSB) and it sounds very
good.

Allison

--
Please reply on the group, no private emails we as a group get to share info that way.

Having built both a phasing receiver and many filter rigs, I think a single conversion filter rig is easier.? ? Why not build a single conversion superhet receiver first.?Good luck? 73? Bill N2CQR

How about a double conversion Rx based on the NorCal Sierra design.

All the crystals for the HF converter are available from Mouser or DigiKey.
They are standard frequencies.You can substitute a LC bandpass filter for
the 4.9MHz IF filter.

Both converters can be NE-602s.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"

Both are easy, just different.
The problem is the one that is least understood will be scarier.

The difference is trading critical RF sections for more parts
in the audio section.

The big feature of phasing is they work as well at 100khz as
they do at 500mhz or higher.

Allison
--
Please reply on the group, no private emails we as a group get to share info that way.

Thank you everyone for the responses, and even a couple of private emails! I have some reading/learning to do and I'm going to have to get EMFRD from the Library again.

I also want to go with a phasing setup because I feel like it's the next bit of evolution in my understanding of radios. I think I'll start with building a DC receiver with phasing, homebrewed. It'll be some time before I get to it though, I am still working to finish a recumbent trike build :)

--
Ryan Flowers W7RLF

Bob,

The norcal sierra is a single conversion.
The uBitx is double conversion with the 45mhz and 12/11.052 second if.

the difference is notable.

There are many single conversion CW radios and a few SSB radios,
the CR series, KNG7A, KD1JV survivor, bitx20 come to mind for SSB.
For CW the 1Watter and The Orgainc from KitsandParts.com.

There are more but memory....

Allison
--
Please reply on the group, no private emails we as a group get to share info that way.

My memory tell me the NorCal Sierra first converts the incoming signal to
about 8MHz then the VFO is used to convert that to the 4.9MHz IF.

The crystals used are 8MHz above the band lower edge.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"