[TenTec] InRAD 2.1 kHz Filter for the Argonaut 509 (The Argo fromHell)

[NJ0IP]

Dear Rich with the radio from hell,

The original SSB board in the 505 used 4 crystals soldered directly to the
board.  Later models used filters with the 4 crystals mounted to a small PC
board.   The latter was easy to swap.  The original a bit more difficult.

I installed an XF9-B (8-pole 2.4 kHz) filter on my 505's board.
Mechanically, I had to relocate several parts to make room.  I also ended up
having to change the oscillator crystal because I couldn't pull the original
crystal far enough to hit the right bandpass thru the filter.  

Lesson learned was to pay attention to filters' exact center frequency.
You probably already know this since you've done many filter swaps, but just
in case...

Once the new crystal was in, everything tuned and worked just fine.

Keep us posted on the repair as well as the crystal filter swap.  If the
filter swap works OK, I might do the same for my 515.

73
Rick

-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Richard Arland
Sent: Tuesday, December 21, 2004 6:47 PM
To: Ten-Tec
Subject: [TenTec] InRAD 2.1 kHz Filter for the Argonaut 509 (The Argo
fromHell)

Gang:

Steve Wilson, XE1UFO, graciously provided what I thought was supposed to be
an Argo 505 (his first rig) as a parts rig for me to cannabalize to get "The
509 From Hell" back on the air. It arrived today. Boy! Was I surprised when
I opened Steve's box and found not a 505 but a 509 instead! Granted it was
in pretty rough cosmetic shape, but it was a 509 and that means I can swap
some boards out in an attempt to get "The 509 >From Hell" to work on 10M. 

For those of you who have forgotten (or have tried to forget) the last
installment, I have managed to swap out all the transistors on the OSC board
with 2N2222As in metal cans. Garland Jenkins from the T-T Lab graciously
provided a new 10M coil and a T-1 transformer (doubler/tripler) coil along
with several of the orange plastic dial pointers that were damaged in the
original order during shipping. Thank you, Garland!

I substituted the coils and got the doubler/tripler to work as it should,
but the rig still won't take off and oscillate on 10M, indicating that the
switch wafers are either badly damaged or not making proper contact. Thanks
to Steve's generousity I now have the ability to swap out the entire
oscillator PCB from Steve's old rig, OR I can remove the switch wafers from
Steve's old rig and put them into mine. Either way I end up with a way to
check out the final stumbling block in getting "The 509 From Hell" to work
on 10M. 

More on this as soon as I can catch my breath and get a chance to pop open
Steve's old rig and pull the OSC board. God willing, I might have a 100%
functional 509 by the first of the New Year.

Now....for the real reason I started this posting................

Has anyone out there ever used an International Radio (InRAD) model 752 xtal
filter in an Argo 509? This xtal filter is made for an IF Freq of 9001.5
kHz. It is a 2.1 kHz wide, 8 pole xtal filter on a small PCB. There are four
(4) pins on the PCB. I have no other information or installation
instructions. My Argo's IF filter is the stock 4 pole, 2.8 kHz 9Meg filter
comprised of four (4) individual xtals soldered into the SSB Gen board (P/N
80131). On all the previous 509s I done the IF filter swap on, they have all
had the four xtals mounted on a small PCB that sat piggy back on the top of
the SSB Gen board.

HELP!!!! I need some info as to how to correctly (the operative word, here)
make the swap and will I need to realign the IF or SSB Gen boards once I do
the swap? 

I am anxiious to do this mod with this  particular xtal filter as it should
really make an improvement in the Argo's receive specs. Speaking of which,
has anyone ever tried using a wide band noise source and a program called
Spectragram to map out the stock filter? The usual "mod" entailed swpping
the 4 pole stock filter with a T-T 8 pole 2.4 Khz xtal filter. I would be
interested in finding out the quantitative difference in doing this mode.
Has anyone tried this todate? 

73 and thanks for allowing me to utilize all the bandwidth

Merry Christmas

Rich K7SZ

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