The xtal filter is located on the SSB Generator board, not on the IF board.
There is no problem to change the crystal filter on the 505. It's no
different than the 509.
In fact I replaced the 4-pole filter in my 505 with a German KVG XF9-B
8-pole crystal filter, which was about the best filter money could buy back
in 1975. I also had to replace the crystal in the 9 MHz local oscillator
and re-align the passbands because the XF9-B was on a slightly different
frequency than the standard Ten-Tec filters. Worked like a champ.
I owned the 505 and the 509 at the same time. I used to swap a lot of the
boards back and forth. Eventually I sold the 505, but I sold it with the
509's SSB Generator board, and kept the 505's SSB Generator in my 509,
because I wanted the better filter in my newer rig.
In addition I also installed a Yaesu 500 Hz CW filter in the radio and had
it switch in automatically when going into CW mode. That, together with the
narrow audio filter in the AGC line gave me great selectivity!
I was working for Rhode und Schwarz at the time, and had access to some of
the best test equipment in the world.
I carefully soldered in a lot of extra thin copper shielding and improved
the ultimate attenuation significantly.
I can assure you, my 509 was a real ass-kicker! (hi)
Unfortunately I sold it when I bought a Scout. BIG MISTAKE.
The circuitry of these rigs is well described in their manuals and they are
totally easy to work on.
Pulling the front panel is only difficult the first couple of times. I
sometimes pulled mine a couple of times in a day. That's what happens when
you are not paying attention and forget stuff!
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of geoffrey
mendelson
Sent: Monday, January 20, 2014 10:49 AM
To: tentec@contesting.com
Subject: Re: [TenTec] Argonaut 505 alignment, filter, mod?
On 1/20/2014 6:55 AM, Neil Martinsen-Burrell wrote:
>
> 2) I am primarily interested in CW with this radio and so I am looking
> for a narrower audio filter. I have seen a Model 208 CW audio filter
> for sale, but it is set up for use with the accessory jack on the
> Argonaut 509. The TenTec wiki says "a slight modification is
> necessary when using the filter with the older Model 505 Argonaut.
> Service Note SN-6-505 details the modifications." I assume that the
> slight modification is to separate out the audio in, audio out and
> power in lines. Does anyone know how to obtain a copy of that service
note for more details?
>
>
I don't know about the 505, but the 509 was occasionally modded by replacing
the 4 pole crystal filter with an 8 pole one from a Triton IV. I think the
IF sections are similar enough to do it, but I would check with someone who
did before you do.
My 509 had the S/SWR meter bulb go, so I replaced it with an LED bulb. I was
going to replace the dial light bulbs with LEDs, but so far they still work.
I think they were rated at a higher voltage than they are used at, so they
won't burn out quickly. The S/SWR meter bulb can be reached from the top,
the dial light bulbs require you to pull the front cover. Something I did to
restring the dial, but hope not to do again for a long time.
You can see my 509 station if you look me up under my Israeli call on QRZ.
:-)
Geoff.
--
Geoffrey S. Mendelson 4X1GM/N3OWJ
Jerusalem Israel.
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