[TenTec] Some Argonauts

[Rick, NJ0IP / DJ0IP]

Steve,

Both radios are great QRP rigs, and collector items.
I've had a 505, then 509, and now 515.

These radio's have pretty hot receivers, but only a 4-pole SSB filter in the
IF chain.  The proper use of an audio filter is critical to the performance
of these radios.  In my opinion, if you buy one of these, you should buy the
matching audio filter and use it first.

These Argonauts use audio-derived AGC which has advantages and
disadvantages.  One advantage is that you can insert a low-level audio
filter in the low level stages of the audio and it filters signals before
they impact the AGC.

The Autek filter is designed to be used after the AF power stages.  Although
it is a great filter, inserting it after the AGC will not produce the same
results as inserting it before the AGC.  Perhaps you could modify the Autek
and carefully control its audio output level and then insert it exactly as
the Model 208 is inserted.

For SSB, you may find the 4-pole filter insufficient in ultimate
attenuation.  In my 505 and 509, I replaced the standard 4-pole filter with
an 8-pole filter and was pleased with the improvement.

I use my 515 mostly for CW and together with the 208 it is very good.
I haven't replaced the 4-pole filter and probably never will.

In any case, these are great radios.
The main difference between the 505 and 509 is that the 505 did not have the
broad band driver and you had to be sure its tunable tank circuit tracked
with the receiver's tunable preselector.  Not a big problem but needs
adjusting from time to time.  The 509 replaced this with a broadband circuit
and you don't have this issue

The 505 and 509 are a bit critical to tune on 10m because they tune 4 times
as fast as they do on other bands.  The 515's local oscillator has 4
selectable crystals for 10m, so this band tunes the same as the others.
The 515 has an updated RX which is more or lest the same as used in the
Triton IV.  

Good luck!

73
Rick, NJ0IP


-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Steve Berg
Sent: Friday, September 28, 2007 7:42 PM
To: tentec at contesting.com
Subject: Re: [TenTec] Some Argonauts

For years I have thought about buying one of the older Argonauts, either 
the 509 or 515 models.  I have never used one.  I would appreciate some 
pointers about the strengths and weaknesses of these radios for CW and 
SSB use.  I can probably adapt my Autek audio filter to one of these to 
sharpen it up for cw, and add a notch.  Any comments?

tnx,

Steve WA9JML
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