On 26 Sep 2007 at 9:26, Kevin Purcell wrote:
>snip
>
> The the last version of the radio is a decent radio. The early 525D
> is pretty good (this is the version Drentea modified). The analog 525
> has a rather low current 1496 RX mixer and is not very good amongst
> strong signals.
>
The analog (525) Argosy had at least two versions of front end, the 1496
and a diode ring mixer. The change came around S/N 850 plus or minus,
don't recall exactly. I have two 525's with S/N's around 1000 and they both
have the diode ring mixers. From what I can tell, the front ends work just as
well as the 525D.
I find this rather curious. At first glance I am not surprised that the diode
ring mixer is superior to the 1496 and in fact I had an early 525 one time and
it indeed had a rather weak front end. But then I acquired a Triton IV with a
1496 mixer and expected an equally weak front end. NOPE! The Triton
was clearly superior to the early Argosy. I am not suggesting the Triton is a
contest class rig, :-) but it is surprisingly robust for a 1496 mixer.
Perhaps because of the tuned preselector. Don't know. My test is on 3585
on the WPA traffic net. Net control is only about a mile or so across country
and with many rigs, when he sends me up 3Khz for traffic, I get blocking
when he keys. Not so on the Triton or the Argosys with diode ring mixers.
All the DSP based radios except Orion experience blocking. In those cases
it is second IF gain reduction, not really blocking. Not very scientific
testing
but a good indicator in my normal operating environment.
> What is the serial number? There are two slightly different versions
> of the 525D (in the first mixer design). This difference mostly
> applies if you add a Noise Blanker (there are two versions for the
> two versions of the front end).
>
I was not aware the 525D had different versions of the front end. Any idea
when that change was made?
All in all, I really like my Argosys. I've made a few mods over the years to
improve the AGC, added a 20db front end attenuator, etc. Nice simple, well
working radios. Good for a simple guy like me. :-)
73,
-Lee-
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