TEN TEC Argonaut 509 and a DDS vfo. December 27th 2012 update: NOW..instead of this 509 having the
N3ZI dds vfo..I have bought a T
EN TEC ARGOSY with a broken PTO ..and I am going to use this N3ZI dds
vfo with a buffer amp for the Argosy. Click on the blue text to link to this new article as I work on this new
experiment. The DDS vfo should be much easier to implement with the Argosy because the Argosy uses a
standard 5 to 5 mhz vfo (injection range of frequencies) vs. the Argonaut which uses frequency multipliers
to obtain different ranges of injection frequencies.
The front panel looks like this. It is a working prototype. I was using it last night to do
some receiving on 80 meters.
It receives very well. I was listening to some interesting cw on the low end of 80. Again
tonight.. (back Feb 15, 2011) I am hearing another wild cw pileup on the lower part of 80!

This Prototype was built using an old 509 I had around here that had a seized PTO.
Instead of rebuilding the PTO I decided to try a somewhat radical modification!
People have actually written me and scolded me for making such a radical
modification to such a fine old radio!!!
Today, I just read where KANGA USA is carrying a new kit. It is a DDS type vfo developed using a different chip from the N3ZI ver 2 that I am using. It is
about $85 for the complete kit. The output is higher than the N3ZI one. Output max around 1.5 v p to p which might be enough to drive the dual gate mosfet
mixer of the Argonaut 509. More importantly, this newer dds is advertised not to have SPURs like other DDS units.
Technology is advancing. I may end up trying another DDS vfo in the argonaut in the near future. Perhaps even this one that Kanga is offering. When I do
build it and try it; I will be writing up my experiences.

Below are some notes from Craig Johnson AA0ZZ. This is from his web site *you can google it. He has other projects and has a PDF file which specifically
deals with topics such as "what happens when you amplify a dds signal"..the concern being SPURS. He claims his DDS unit..is a "clean" running dds
without a problem with spurs. My Argonaut (when tuning certain bands) had birdies and spurs. I am not blaming the N3ZI dds vfo. I think I was using
perhaps too much amplification..(overdriving) with my 2 transistor amplifier. NOTE: I did not build a bandpass filter for the Argonaut DDS vfo because the
vfo frequencies change from band to band.
Because of the complexity..I have decided to abandon the Argonaut 509 DDS control and go back to the old
PTO (after I rebuild it). The PTO had frozen.

I had thought that a DDS vfo for the Argonaut was a good idea ..and it still might be..BUT..I have decided against it. If you are considering trying this
yourself..you can use some of my ideas but be prepared to do some serious building and modification. Still..it was quite a thrill to make some contacts with
this butt ugly breadboard kind of radio. Just like the old golden age of radio back in the good old days!! You cobble up something and try to make it work.
Its not perfect. It has harmonics and birdies and there is qrm and all that..but the qso really stands out because you made it using your own hand built
gear. Gear you understand. Gear you can work on. Gear you can actually repair yourself. I can work on this gear. The FT817 would be a real challenge to fix.
I guess board level repairs would be possible..but you would have to have a set of spare boards.

The FT301 is the next victim of my soldering iron. It is an old unit. It works but the display is not working properly. A DDS display will  fix that. The finals are
fried in the FT301. NO PROBLEM either. I will use it at the 10 watt level as a QRP DDS controlled rig. Certainly not a small portable neat little unit..but
something to work on.

Just because I changed my mind about using a DDS vfo with the
Argonaut 509..does not mean..it cannot be done.

It certainly can be done. In my case..I had an FT301 transceiver
that had a few problems and I decided to rebuild it with the N3ZI
version 2 vfo (removing it from my argonaut). The Argonaut 509
will now have a rebuilt PTO..(I have one now) which will go back
inside the spot where the DDS used to be.

The N3ZI dds board fit perfectly in the cavity where the 509 PTO
used to be. I built a spacer board using blank fiberglass circuit
board and 4 standoffs to mount it..as per the picture (LEFT).

I had a few qsos with the Argonaut dds as well. I did have spurs. I
used an amplifer (see schematic near top of page). I did not try to
match the impedances nor did I tailor the drive level to the circuity
of the Argonaut mixers.

I tried patching in to the argonaut circuitry and use the mulitplier
stages to produce the injection frequency BUT..the digital readout
would then not display the proper frequency. It would be skewed.

Im hoping to have better sucess trying this N3ZI unit with the
FT301. The FT301 has a 5 to 5.5 mhz vfo and i can use a bandpass
fillter after the dds vfo and amplifier to cut down on
spurs..(hopefully). The same thing could be done with the
Argonaut but would require 5 separate bandpass filters for each
set of injection frequencies. IT GOT TOO COMPLEX and I decided
not to go ahead with it.

IF YOU DECIDE TO TRY THIS PROJECT in some form or other..I'd
really like to hear from you. I can even write up  your sucess story
in an article for this magazine.

Remember..we are amateurs and this is a hobby. We are not all
professional engineers. I am a technician by training and I don't
have a sophisticated machine shop or anything at my disposal.

Sometimes I don't always get professional results!

The FT301 is larger and will allow more room for shielding and additional circuitry. It will not be a portable UNIT. but a stay at home radio. I may not fix the final output
circuit as the replacement transistors are costly..BUT RATHER..i CAN use it as a 10 watt qrp radio. With the 301 ..it is a simple matter to convert it to a full time qrp rig.
It was made with a detachable 100 watt heatsink and you can wire the driver circuit with a coax jumper cable to bypass the final PA stage.  Yaesu did make a qrp
version of the FT301D that was the FT301SD. Same basic circuitry and layout but the PA stage was not included.
Above another schematic and some information from the AADE Almost All Digital Electronics web site. This might be a good amplifier for the DDS vfo.
I dont have any of these parts yet..but I will be trying to buy some LT1252s ..looks like a good circuit.
ABOVE: A working FT301D with issues. 100 watt PA stage will
be removed (easy to do with the 301 modules) and it will be
turned into a 10 watt rig with the N3ZI DDSversion 2 vfo which will
also cure the burned readout problem it has.
IF....you happen to rebuild your Argonaut 509 with a dds vfo..I'd like to hear from
you. If you send pictures and give a bit of information..I will write it up for you..or
you can write the article and I will feature it in my magazine. NOTE: Some Argonaut
owners and QRPers have written me that they think I am committing a big sin by
so drastically altering or modifying the Argonaut. The early Argonauts have a
great deal of sentimental value and memories.

The Argonauts came into ham radio and QRP back in the early 70s and Ten Tec
was just a small wee outfit manufacturing items such as the Power Mites and their
modules to build similar radios. ...Then..the ARGONAUT 505 and 509 came along. A
nice little superhet rcvr and sensitive and SSB and Full Break in CW. I bought my
first Argonaut new in 1974. Long LIVE THE ARGONAUT! I wish some company
would build a similar (simple) perhaps a bit physically smaller but good Argonaut
with a bit more modern circuitry but no real complex ICs or microprocessors or
PLLs. A kit form would be good. One fellow called the K2 the mother of all kits! I
think a simpler rig qrp but all the bands..would definitely be welcome. And
American Made like the old Drakes and Heathkits that so once dominated our
This homely argonaut 509 dds prototype is being boxed up
for awhile and I will try plan B ..implementing a DDS vfo the
FT301D pictured beside it.

I may..in the future..buy another DDS vfo and try the
experiment again with the Argonaut 509.

There are newer DDS vfos comming out now and they
claim to be cleaner and higher power output. Perhaps then...
Below: the schematic of the Argonaut VFO (a Permeability Tuned Oscillator) with multiplication scheme to provide the "injection
frequencies" to be heterodyned to a 9 mhz IF. At the very output ..a 47 pf capacitor will sample some of the injection frequency
and display it on a digital display.  This is from the AADE web site. Almost all digital electronics. (easy to find with google!).
LINK BACK to page one of hamelectronicsmagazine.com

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This article is being
redone..march 2 2012..its in a bit
of a jumbled mess right now..
soon to be fixed up and so will
be the dds vfo..73 earl ve3ab

(too many projects and irons in
the fire..cant seem to get the
projects properly done! the path
to hell is paved with good
Three different models of Ten Tec Argonauts. The 505 (right top) similar to the
one I bought new from "UNCLE RAY" VE3UR in Scarborough ..back in 1974
when I first got into QRP seriously and I joined the QRP arci (3757).

All these argonauts are on the shelf and not modified. The modified one
..right..is being worked on. I set it aside last spring (2011). I had hit a bit of a
DEAD END..with this one ..but I will be (soon) firing it up again and firing up the
soldering iron as well.

I have a few ideas to get the circuitry working. A better DDS amplifier with
better filtering so that I don't get all the birdies!
The N3ZI dds vfo kit was built and it works fine. It will mount just fine inside the cavity
where I removed the PTO assembly of the Ten Tec Argonaut 509. I made a sub panel
of fiberglass board to help support the DDS board.

Below the assembly being tested on the bench. A working prototype. A blue board with
point to point wiring of a DDS amplifier circuit.

I will be revisiting this project again here in March 2012 and April. Im going to try and
get it going with some circuit enhancements.
The top side vfo assembly of the 509 is basically unmodified. I run an rg174 cable to a
terminal strip and I am experimenting with tapping in on various points. I can tap in at the
fundamental vfo frequency and use the existing multiplication and amplification stages or I
can bypass these and tap in and run the dds vfo at the "injection frequency" for the
mixers of the argonaut 509. I was fiddling around with both ideas (before) spring 2011.
Right..I took the parts I removed from an old argonaut and filed them away in case I want to abandon the DDS modification project. I can always return the Argonaut back
to its old self again and rebuild it! -- I might end up doing that--
Update: Dec 27th 2012..YES..THIS IS EXACTLY WHAT IAM GOING TO DO. I have purchased a new to me..Ten
Tec Argosy. It has a badly broken PTO (might have got damaged during shipping).

..I'll give it one more try this spring with some new ideas I have. If that doesnt work out..I will have a PTO rebuild kit on order from Ten Tec and while Im at it..Im ordering
some other spares ..including a band switch linkage assembly for the 505 I am tryiing to restore to proper operating condition..(Feb and March 2012).
December 27th update: This Argonaut is going to be restored and its old PTO rebuilt.
Iam going to discard the prototype front panel and go back to the original "stock"
I gave up on trying to adapt the dds to the Argonaut 509.

I have decided to restore it back to its old self..but..you can still
view this article as I was experimenting.

Argonauts 505, 509 and 515 are SACRED COWS..AND SHOULD
at least..this is so..in my books..72 earl ve3ab