____________________Reply Separator____________________
Subject: Re: [TenTec] 'New' Triton IV / 540 questions/comments
Author: "Michael O. Hyder" <N4NT@charter.net>
To: <tentec@contesting.com>
Date: 3/4/00 12:33 PM
See Below . . .
----- Original Message -----
From: <streyle_john@si.com>
To: <tentec@contesting.com>
Sent: Saturday, March 04, 2000 10:31 AM
Subject: [TenTec] 'New' Triton IV / 540 questions/comments
> 2nd: The receiver seems kinda weak on receive - the calibrator doesn't even
> move the s-meter. Is the RF amp mosfet the likely cause? I've been thru most
> of the alignment, which helped a bit; but not enough. TT service told me over
> the phone that either the mosfet, or the protection diodes were typically the
> problem. (Even at that, I've been able to work some decent DX on 80 & 40 CW,
> with just an inverted V)
** There is a slide switch on the back panel which switches the receiver
antenna between transceive and a separate receive antenna jack on the rear
panel. Make sure this switch is in the correct position -- then wiggle it
back and forth enough times to clean its contacts. Those things are
notorious for getting dirty.
** If that doesn't work, then look on the schematic for back-to-back diodes
across the receiver circuitry's antenna input. These diodes are present to
protect the receiver from voltage spikes, but sometimes the way they protect
it is to short out, which makes the receiver seem pretty near dead. While
you are in there, replace the diodes in the ALC detection circuitry. If
they go bad, funky stuff can happen on transmit.
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I tried the slide switch on the back panel; no improvement on receive. I lifted
one end of both of the back-to-back receiver protection diodes; no improvement
on receive. Next, I tried feeding a signal into the input of the TX-RX mixer,
and set the signal generator level to produce an 'S9' reading. I then moved the
signal generator to the antenna jack, and got an 'S9 + 15' reading.
Apparently, this means the RF amp stage is working properly, according to what
TT service told me on the phone.
I've already tweaked the alignment on the RF amp, mixer(s), and IF. It's
probably not perfect, but should be pretty close.
Is this normal operation for this radio, to show S0 reading on 80 meters? (with
only normal background noise?) I'd expect a couple S-units of normal 'crud'
there. I'm using an inverted V for an antenna.
Incidentally, while I was inside the radio, I took the cover off the VFO
pre-mixer. I noticed an intermittent while loosening the screws. Apparently,
the tall coil in there was interfering with the cover, and has produced a solder
fracture or broken trace on that board. (Okay, maybe my 'alignment' efforts also
played a part.) I plan to pull that board (pain!) and resolder; but also, I plan
to trim that coil form off a little bit - so it won't hit the cover. Has anyone
else had this experience?
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** If you don't have the OVP, GET IT. Ten-Tec had them recently for $15
plus $3 shipping.
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Thanks for the tip - I will definitely pursue this soon.
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> Thanks in advance
> John Streyle
> N0JS
** Welcome, de Mike N4NT@charter.net
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