New (and improved!) Argonaut Circuit Boards in the works. -- I am starting to approach small business and manufacturers in order to
see if it is possible to have some newer and improved updated circuit boards made up for the Ten Tec Argonaut 505 and 509.

----> The existing boards are quite primitive by todays standards and the 505 circuitry is compatible with the 509 so that..a 509 board
will generally work as a pin for pin drop in replacement..in most instances.

---> The first two boards Im going to try and get built are the Control Board (to replace the 505 control board with hard to get reed
relay) and secondly: the audio board which in the 505 uses old hard to get germanium transistors that is failure prone.
How about starting with the Final PA stage. The Argonaut 515 final Amplifier (RF output transmit) is pin for pin
compatible with the Argonaut 509 RF final output stage. The 515 stage is an improvement with greater power output that ranges to around 8 watts or even 9
watts in some cases with a pair of 2SC2075 (MRF476s). The board itself is not all that complex..and I have some extra 2SC2075s I bought from Dans Small Parts
a while back-- so Im thinking I will try to approach FAR CIRCUITS in USA to get an estimate on the cost of making some "knock offs"of the 515 board. I may even
approach Ten Tec and see if they will supply new boards.

Im hoping the new circuit boards will be "modern"type boards with crisp circuit lines and etching. Something like the nice boards I have gotten lately from
W8DIZ the qrp kits and parts person USA.
I don't think Ten Tec will mind me doing this. The Argonaut 505, 509 and 515 series was manufactured over 30 years ago and is long since out of production. I
only plan on making up a small amount of boards ..say 10 to 20 at the most. As is my usual practice here with this little hobby type business..I will be marking up
the boards about 20 pct as a tiny slim profit (helps pay for my ham hobby in my retirement).
BELOW; I did a bending exercise on the leads of the 2SC2075 when trying to replace some
transistors on a 509 board. I did not install the emmitter lead resistors (see the 515 schematic
here on this page). The transistors got red hot even with a respectable home made heatsink.
Below..as schematic of the Argonaut 515 final PA stage. NOte: the 2.2 ohm resistors are
wired right onto the emmitter leads of the final transistors. AT FIRST..I did not use the 2.2
ohm resistors and the transistors got RED HOT!!! These resistors are very necessary.
So..this fall/winter of 2012/2013..I will be trying to get made some 515 Argonaut Final PA boards for use in the older 509 Argonauts. So..if you are
interested..email me and I can guage how much interest there would be in this project.

I'm going to write FAR Circuits and send them along a sketch of the Argonaut 515 final board and the 509 audio board and see how much Far
Circuits will charge for doing the boards.

I don't have a huge budget with my pension here..so I will likely only order something like 10 to 20 boards total. If you would be interested in the
new boards..just drop me an email at my address: earlinclayton@yahoo.com (note: I no longer live in Clayton Ontario but have moved to Elliot
Lake, Ontario. I just kept the old email address alive.
The OTHER BOARD..I want to get manufactured is a 509 Audio board (uses an IC) to replace the 505 audio boards which use germanium
transistors. The 505 audio boards seem to get damaged fairly often and the germanium transistors are not always easy to get..so a new
audio board will also be in the works in the fall and winter of 2012/2013.
This green square shows the 2.2 ohm 1/2 watt carbon
compostition resistors which are mounted vertically.
The complementary pair got blown on the board above. I removed the
transistors and replaced them with another pair of germanium transistors
from my rather large junk box. There were no heatsinks on the ones I
used so I made a pair of heatsinks by cutting one in half from my junk
collection. A bit of an ugly fix but it worked.

Better solution is now in the works. I plan to approach FAR circuits or
W8DIZ and perhaps Ten Tec and see if I can get permission to have
ARgonaut 509 boards made up..using newer technology for a much nicer
looking fiberglass board. W8DIZ makes nice boards for his kits. and that is
what I would like to see in my older argonauts.
With the 2.2 ohm emmitter
resistors, the MRF476 transistors
behave themselves and don't
over- heat.

I actually measured 9 watts out
with my new matched finals.

The Argonaut low pass filter and
other components seem to be able
to handle this amount of power but
I think anything much over 10
watts would be pushing things a
bit.

True qrp is 5 watts out maximum.

Actually..I usually run my Argonauts
in conjunction with my 405
amplifier and I turn down the
power to drive the amp at about 20
watts ..many times on CW. I don't
really need 50 watts output most of
the time with cw and during the
qrp contests I use only 5 watts out.
The argonaut 505, 509 and 515 are radios that the average ham can still work on.
The parts are still widely available. Dans Small Parts in USA sells these
MRF476/2SC2075 (C2075 marked on the part)..note: with transistors ..the 2S is
many times dropped ..as I guess..it makes for more room on the part to print the
part nr.
If you look C2075 and 2SC2075 in the NTE semiconductor cross reference..you
will see they refer to the same part.
Ive had a number of fellows write me with problems with this 505 audio board.
One fellow: now SK Jim VE3DJX replaced the Germanium transistors with
Silicon ones in his 505 he was working on.

I plan to get some 509 audio boards made up this winter and it should help
people out. Of course some purists will like to keep the same old original
boards and parts.

One thing that should be done..to protect the audio transistors ..is to use a
series diode to ensure that if the radio is connected up backwards to the
power source..the transistors wont get fried! They do fry easily.
A reverse polarity protection circuit for the 505 would also be a good idea.
This page under
CONSTRUCTION   ..last worked on 27 August 2012. I will be doing this new Argonaut circuit boards project this
winter..and ..maybe..I will expand it so that I will have more brand new boards for the Argonaut. Who knows??
73 earl ve3ab
The old 505 board uses a reed relay for TR switching. and is obsolete long ago.
The newer and improved 509 control board (above). You can see the dual in line
IC lower right hand corner.
The new audio board -- Argonaut 509 that replaces or (will replace) the old 505
audio board with its germanium complementary output transistors.

I have gotten a number of emails from hams who are fixing this audio board as it is
prone to failure and the transistors are both expensive as matched pairs and a bit
hard to get. The newer audio board is far superior.
Later on..down the road..I would like to make available argonaut 515 circuit
boards for the RF final output stage.
Updated this page: Dec 1st 2012