There are lots of signals at the output of the CA3053 mixer as seen on the spectrum
analyser. I'm not really too interested in what each blip on the screen represents. I just know
that the mixer has plenty of strong outputs and that is good enough for me. I know there will
be the desired 14 mhz output. There will be the 9 mhz IF transmit signal and a 5 mhz vfo
signal which when mixed with 9 mhz produces 14 mhz.
The output of this stage with all the harmonics and mixing products goes to some filtering
and is amplified by a driver transistor and I believe filtered again then passed on to the PA
stage (final amplifier stage) and then boosted to about 3 watts qrp output and then filtered
by low pass filters. The PA stage is broadband and the filtering is adequet for qrp work.
I strongly think that the problem is now likely blown/damaged final out put transistors.
What I have to do now is get at the final output board. I want to remove that board and then
insert a dummy load resistor to terminate the output of the driver stage and see if there is
drive power. I think the drive will be likely about 300 milliwatts or so. I assume here that the
linear amp PA stage is about a 10 db gain stage.
Judging by what I see..the 505 final output stage is not easy to work on and requires me to
remove the front panel to gain full access to the PA stage board. So..I will do this over the
next few days and take some pics and write it up.
If the PA stage transistors are indeed blown as I suspect..it would require some subsituting
of parts. The original transistors used by Ten Tec in the mid seventies are no longer easy to
buy or are expensive to buy. I have some MRF types around here that are supposed to be
pretty good..so I will be trying them out in this circuit.
I will be writing more info in the next few days as I proceed to get this venerable old 505 back
in the pink again. I will look forward to doing some operating with it as well and will report on
that too. I had a 505 back in 1974 and it will be like old times again using this radio. I used to
operate qrp cw contests with it and it was quite a challenge but alot of fun. I also operated
some 10 meters sporatic E openings with the 505 and made lots of contacts.
|Ten Tec Argonaut 505 - the first Argonaut that Ten Tec brought out in 1974 (I'm going by memory
here). Some pictures and discussion as I go over this unit that needs some TLC. It is not receiving
or transmitting. This page and project started 20 Feb 2012 and the article should be finished in a
couple of weeks time. You are quite welcome to follow along.
|A project by Earl Andrews VE3AB..Feb 22 2012..one of my winter projects..many more to
come on this web site www.hamelectronicsmagazine.com (a free on line magazine)
|Page 2.. Now tracing the transmitter stages to find out why I am not getting
any actual power out to the dummy load/coax. I now leave the previous
stage..the SSB generator board and the transmit signal (9 mhz) now enters
the Transmit Mixer a CA3053.
I put the probe on C14 ..the white colored trimmer capacitor. Looking at the schematic above: could it
be any simpler??? the Argonaut is a pretty basic and straight forward radio that can still communicate
with the $4,000 radios that still use ssb and cw!!!!
|Theres more to come in this series with the old 505
Argonaut. I will be fine tuning it and using it on the air. I
hope to use it on Field Day this year (2012).
Repair of Vintage Ten-Tec Transceivers
Ten-Tec Service Department stocks a very comprehensive line of component level parts for our vintage transceivers. We can repair
most transceivers that we have built in the past 41 years. However, there are individual transceivers that can no longer be
1.Many vintage transceivers are mechanically worn out from years of use. Most notable worn part is the mechanical band switch.
Switch indexes are no longer available. Most but not all individual switch wafers are available but it is very labor intensive to replace
2.Many circuit boards have become intermittent after years of heating and cooling, expanding and contracting during the course of
normal operation. Intermittent problems on circuit boards can be repaired but this is most often a slow time consuming process to
locate the intermittent solder connection or trace on the board. (earls note: I repair circuit boards. People have sent me
boards from the FT301s..that they suspected problems with. I swap them in my working rig and I can locate the
defective board pretty fast. Most problems have been poor solder joints. One was right at the 9 mhz filter. Others I
have found on the trimmer capacitors that are tuned circuits). (When I do this work..I only charge $10 per hour. I only
charged the fellow $30 for these types of repairs..(typical) of my prices.
3.Many vintage transceivers have undocumented modifications. These modifications often render a transceiver un-repairable since
the service technician often can not easily determine the nature of the modification and its effect on the operation of the transceiver.
Some documented modifications will also render the transceiver un-repairable since the modification drastically changes the
operation of transmitter or receiver. Earls..note: I actually dont mind doing this type of detective work! Im doing this now
with the 505 I am working on). The only thing I don't feel comfortable about tacking is the double tuned circuits that ten
tec uses. You probably need a sweep generator..and I just havent gotten around to using mine and getting some
alignments sucessfully done on my own gear before tackling some one elses.
4.Many vintage transceivers purchased from on line auction sites, hamfests and yard sales may not be as advertised and may
require extensive repair to bring them up to original specifications.
Ten-Tec Service will evaluate your vintage transceiver. If it appears that the repair cost will be excessive we will give you an estimate
for the cost of repair before any repair is attempted. If you decide not to have the transceiver repaired there will be a charge for one
hour of labor ($60.00) to cover the cost of the bench time necessary to evaluate the transceiver. We will then ship the un-repairable
transceivers back to you at your expense.
I can do many evaluations by email and photos of your defective radio. I dont charge for this. Ten Tec has a $60 per
hour rate. Mine is $10 per hour ..but I work from home in my spare time..(I took early retirement). Ten Tec has a factory
and factory grade equipment and I do not. I am working to buy a few better pieces of test gear in about another year or
I can do some certain repairs and reworks that might otherwise be way to costly for the pros to do. I took the 2 year
Electronic Engineering Technician program in College and I graduated in early 80s. I am familar with 1970s/80s stuff. I
still work on it. Even when I was working in the Nato system at my day job previously..I was working with older
technologies on older solid state components mainly.
If you want to repair your vintage transceiver, we will sell you the parts to accomplish the repair. Please send an Email to
firstname.lastname@example.org with the Model number of the transceiver, a description of the part and the Ten-Tec part number if available.
|Here are some notes from the Ten Tec web site. I just searched for "vintage
repairs" on their site and came up with this.
--->> I dont mind spending extra time to undo some mods but as the Ten TEc
site says: certain mechanical problems like switch indexes are tough to fix.
Depends on what needs to be done. email me and we can talk about repairs
I can analyse the situation and even examine photos and I DONT CHARGE a
thing for this kind of advice! Its my retirement activity. I make my money from
the early retirement pension that I was fortunate to get!! I just do these
activities to keep my mind stimulated!! and I enjoy it too!!!
|I buy old radio gear and parts as
and as well I will take on certain
repairs that I feel I can do a good
For MAIL ORDER..often people just
send me the circuit boards that are
suspect and I can plug them in to
my Argonaut 505, 509 or 515.
I have all three models working.
or FT301 or FT221 2 mtr all mode.
Atlas 210x as well.
Heathkit gear is fairly straight
forward for me to work on because
the manual is laid out in such a way
as it allows for the builder to make
adustments and even do
alignment in some cases.
To send a whole radio to me is
sometimes OK if it does not need
new final transistors. I only have
low power and QRP finals in stock.
Old Ten Tecs have some certain
transistors that are really hard to
get..so..I have to experiment
sometimes with substitute
|I need access to the FINAL PA section of the Argonaut 505. The front panel and all the knobs and some fastening hardware needs to be
removed before I can lift out the PA circuit board with the 2 final transistors. This is a QRP radio that will not put out much more than 3 watts
maximum. Right now, there is very little output power as measured with my spectrum analyser at the output jack of the radio. I tested the
output at the relay to see if it was perhaps the relay not operating but it seems the PA section is likely the problem. It is acting like an
attenuator rather than the 10 db amplification stage.
The corner braces being removed from their fastening to the end plates. This is
a radio that can be worked on by the average guy..if he is carefull and makes
sketches or takes lots of digital photos ect. I have never even seen the insides
of an FT817 or an IC 706. I have an FT757GX and I have taken it apart one time to
do an adjustment. It is considerably more complex than the Argonaut. I don't look
forward to the day when my FT757GX acts up?!! The newer rigs are great to
operate. My 757GX can be cranked down (easily) to qrp levels on cw.
It has nice filtering and IF shift ect. When it comes to working on gear and doing
fixes and repairs..the old stuff like the argonaut 505 or 509 are more my style.
I only paid $300 for my FT757GX. If it breaks down the road..I may part it if I cant
close up of the little clip that holds the dial in place -- I'll write a bit more..this is a work in
progress..(26 Feb 2012). This article is being written as I go along with this little project.
I use packing tape to secure the little mounting screws for the corner braces to
the Argonaut end plates. Since I don't have a photo graphic memory and I some
times forget what screw goes with what hole..I fasten everything near where it is
used. Iam now going on 59 years old. All these little projects are an exercise for
the mind and spirit. I hope when I die and go to heaven..I will have a workshop just
like the one at home here. A cottage lot and a few fishing holes as well!
The PA output board..... end of article ..so far...1 pm Sunday Feb 26 th. I am taking a break. I will be writing more (a new page) with more pictures and information.
I hope to have the Argonaut 505 back in operation again in the week upcomming. I will be choosing a new set of final PA transistors..(if need be). I am still not sure if
the finals are blown or maybe something in the driver stage prior to this PA final stage. More to come..in next few days..I will be discussing alternate and subsitute
devices for the Ten Tec Argonaut 505,509 and 515. All transistors are not created equal. 73 earl ve3ab
PROBLEM SOLVED... February 29th 2012...I did some measurements
using my spectrum analyser on the RF chain..predriver worked fine
but the RF driver a 2N4427 was not amplifying.
I took the driver transistor out and it had an open circuit on one of the
junctions of the transistor.
That is an easy test using the diode test function of a common VOM.
I replaced the driver and still no RF out of the rig itself. The finals were
blown as well.
I swapped in a working final PA board from one of my Argonauts 509s
and BINGO..I had some RF output..maybe about 1.5 watt. So the rig is
now working but limping a bit still. Perhaps the driver transistor I used
does not have enough gain. Anyways..if you are interested in more
pictures and discussion..I have created yet another page...
click here to see page 3 of this Trouble shooting and Fixing the old
Argonaut 505 Qrp transceiver.
link here to the next page where I get the
rig up and running.
PAGE 3 LINK HERE >>>>>>>>>
LINK back to page hamelectronicsmagazine.com -- on line free
magazine..free of advertisements as well..(just me tooting my own horn (I
sell qrp parts on the side!!) and I do some mail order repairs from time to