Geoff,
The nicest thing about the 505/509 was that there was plenty of room inside
to work on them, and the manual was outstanding. It gave a circuit
description of every stage in the radio.
I built an 8-pole "XF9-B" xtal filter into mine. It was pretty much the
best xtal filter on the market at that time. I added a bit of additional
shielding between the input and output by soldering in little strips of thin
copper in various places, which improved the ultimate attenuation
considerably. I also had to replace the crystal on the SSB Generator Board
because the XF9-B was slightly off frequency from Ten-Tec's filters. The up
side was, it was then on the right frequency to enable the use of a Yaesu
500 Hz xtal filter. I used relays to switch xtal filters, with "NC" having
the CW filter in-line, so it did not draw extra power when working CW.
I didn't see a problem with the sensitivity as long as you did not use an
amp. I felt I could hear anything that was able to copy my 5w. I also
don't recall it being too sensitive on 40m. The tunable preselector was a
GREAT help. Most of the tiny 40m QRP radio kits in the states seemed to
crumble here in Europe. The problem with shortwave broadcast stations is
just too huge for them. No problem for the Argonaut.
I honestly cannot imagine a better small all-band (ex-160m) transceiver for
traveling and working off of batteries.
Even the K2 drew too much current for that type of work. People don't
realize this, but it is the receiver current drain which runs down the
battery, not the TX. Nothing beat the Argonaut!
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Geoffrey S. Mendelson
Sent: Wednesday, July 04, 2012 9:59 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] My First Ten-Tec
On 7/4/12 10:49 AM, Rick - DJ0IP / NJ0IP wrote:
> You know Steve, the Triton IV was one fantastic radio.
> It had a really hot receiver. I think that was one of the best kept
> secrets of that era.
> An even bigger, better kept secret is that the Argonaut 515 had the
> Triton IV receiver in it.
> It was really hot for a QRP radio.
The 509 is pretty good too. If you look for mods for it, you can find both a
mod for improving sensitivity (replacing front end dual gate MOSFET with a
3n211 or the RCA equivalent) and a mod for reducing it (claimed to be too
sensitive on 40m). :-)
You can also replace the 4 crystal filter with an 8 crystal one scrounged
from a dead Trition.
Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379
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