[TenTec] 546 Omni ''C''

[Michael O. Hyder]

ANOTHER OPINION (seems everybody has one):

To offer even more clarification and to put everyone on notice.  First note
that I do not work SSB so none of my comments have anything to do with SSB
preferences.

About all the Ten-Tec rigs had the audio CW filter as an OPTION.  If you
need one to add to a rig now, you are probably going to be out of luck -
except the one for the Argosy is available as a kit from Embedded Research.
Probably it could be adapted to the other rigs.

I don't know about the newer rigs (Omni-V and VI) but in the older ones, the
AGC is derived from audio.  In most of them the sampling point for the AGC
was AFTER the audio filter.  That means that if a signal was out of the
audio passband, it would not pump up the AGC.

I have two Argosy rigs.  In one of them, the AGC sampling is done after the
audio filter, but in the other one, the AGC sampling is done before the
audio filter.  That means that even though you cannot hear the signal, it
can still pump up your AGC.  For the life of me I cannot figure out why they
did it that way in the later Argosy rigs.

As for the Omni-C - I prefer the audio filter to the crystal CW filter for
almost every condition.  Others may not.  I like to use the 2.4 kHz normal
SSB crystal filter position because that makes the audio sound the most like
the Tritons (which is 'perfect').  To get the same sound from an Argosy
requires replacing the stock 4-pole SSB filter with the model 220 eight-pole
SSB filter (yes, even for CW).

Steve said that the Omni-C was the best rig Ten-Tec ever built.  About 10-12
years ago I was using one and got a Hercules 444 amplifier (a mistake - it
went into self-oscillation and caught on fire - cost $450 bucks to fix and
Ten-Tec told me mine was the LAST they would work on).  I was thinking of
getting a Corsair II and when down at the factory picking up my Hercules, I
was talking with Al Kahn who was then the owner of Ten-Tec.  I asked him if
the Corsair II would switch my Hercules from band to band.  He thought not,
but called in Larry Wirth to ask him about it and about the feasibility of
installing another bandswitch wafer to do it.  Then Al asked me what rig I
was using and I told him an Omni-C.  He said, "If you have an Omni-C, then
you don't need a Corsair II!"  and that was the end of that discussion.
Seems Al liked the Omni-C a lot.  By the way, Al did a lot of mobile CW and
had his choice of any of their rigs.  He ran the 580 Delta, which says a lot
for it, too.

For a Zen radio (one that just does not intrude into a CW QSO), I believe
the Triton 544 is the best.  My second choice is the Omni-C.  Third choice
is the Argosy with the 8-pole SSB filter (and I NEVER work SSB) and proper
AGC sampling.  Either of them will just sort of vanish and leave you with
what seems like a direct connection to the other end of the conversation.
If the Triton 544 had 30 meter coverage, I would use only it (and it has no
provision for a CW crystal filter - and I've NEVER missed it).

Nuff said.
73 de Mike

----- Original Message -----
From: Steve Ellington <n4lq@iglou.com>
To: Donald F. Smith <n4jzh@mindspring.com>
Cc: <tentec@contesting.com>
Sent: Wednesday, April 07, 1999 8:22 AM
Subject: Re: [TenTec] 546 Omni ''C''>
>
> Further clarified: It has no optional crystal filters. The 2.4khz filter
> is used for both transmit and receive and is soldered in. There are two
> extra filter slots open, 1.8khz and .5khz. The 150hz filter mentioned is
> an audio filter which has 3 positions, providing bandwidths suitable for
> cw. This audio filter is in the agc loop and does an amazing job but not
> quite as well as having the optional filters.
>
> The reason I bring this point up is because I've run into a lot of
> confusion and mistatements about what filters a rig actually has.
> Recently, a Delta 580 was advertised as having "all factory filters". The
> owner wasn't familiar with TenTec rigs and since all filter positions
> seemed to work, he assumed it had them. I had him remove the top lid and
> look. He still couldn't tell if the .5hz filter was in there. Anyway, I
> bought it and of course, had to order a filter for $89.
>
> TenTec was big on audio filters. The Tritons, Argonaught's, power mites,
> Century's amoung others, all used them for cw reception enhancement.
> Later, with the Omni, Delta and Argosy's crystal cw filters were offered
> as options to the already effective audio filters. These crystal filters
> provide better strong signal rejection. Still later, the crystal filters
> became predominant as in the Paragon and Omni V. In these, the audio
> filter was taken out of the agc loop and lost it's reputation as an
> effective filter. Now if you want selectivity, you must shell out the $$$
> and buy the crystal filters.
>
> The Omni C had the ultimate combination of audio and cw filtering. A 3
> position switch allowed selection of 3 crystal filter bandwidths and
> another 3 position switch provided 3 positions of audio filter bandwidths.
> All six were within the agc loop! My favorite setup for cw is the 1.8khz
> crystal filter and position 2 of the af filter. Listening to cw with that
> setup almost brings tears of joy.



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