[TenTec] Century 22

[Garry Nichols]

Thank you, Richard.  Yes, this number 700 keeps popping up.  Maybe all
succesive commenters are simply passing along that number from the first
one!

I do have the manual in PDF, thank you!  I guess that is the only doc on
the rig.  Too bad that there is not a service manual!

73,

Garry

On Sun, Aug 22, 2021 at 5:06 PM Richard AG5M via TenTec <
tentec at contesting.com> wrote:

>
> I have S/N #009 and #679 C-22s. I heard there were 700 made, if that is
> accurate. Perhaps someone can confirm that. I have not made any changes to
> mine. Nice radio. Do you have the full manual in PDF form? If not I can
> send to you. 73, Richard AG5M     On Sunday, August 22, 2021, 09:45:50 AM
> PDT, Garry Nichols <garrnich at gmail.com> wrote:
>
>  I've been approved at the Ten-Tec groups.io discussion but it looks like
> some folks are still at this discussion site.  No one replied to the post
> Gary made for me before my approval, so I will repost here to see if I get
> any replies.  TU,  Garry  WA1GWH
>
>
> I picked up a C-22 in July, S/N 666.  Does anyone know how many were
> produced? I am wondering where mine sits in the production run and what
> might have been changed along the way.
>
> I've heard that some of these rigs had capacitors in the AF filter that
> lowered it to 500 Hz center frequency and that C41-C48 (.0033) should be
> replaced with .0022.  Have not examined that on the board yet but wondering
> if by #666 this had been corrected.  And if those cap numbers and values
> are correct.
>
> The variable bandwidth AF filter is very effective but I do not like the
> way it sounds.  It is always set for minimum bandwidth and the adjustment
> pot just bleeds varying amounts of unfiltered AF into the output stream to
> the LM380 to widen the bandwidth.
>
> Because it is set for minimum bandwidth (200 Hz in TT specs) it has a
> pronounced "sea shell" effect on the audio.  This is apparent even when
> blending in large amounts of unfiltered AF.
>
> Is there any mod to widen the bandwidth?  Looks like I can drop off a stage
> or two of filtering to widen it as was done with the C-21 switch selected
> bandwidths.  I have pretty good mental selectivity.
>
> I would also like to lower the center frequency somewhat below the 750 Hz
> design.  Is there a mod for this?  (I've apparently answered my own
> question, above.  But with the filter dialed out the rig still seems to
> have a peak around 750 Hz to my ear.  Perhaps there is some filtering
> before and/or after the AF filter?)
>
> My radio has the built in Ten-Tec keyer but I get unsure code with my
> iambic paddles (which I simply push side to side, no squeeze keying).  I'm
> thinking the keyer might need a single paddle key to work correctly?  I may
> be confusing it with a dot or dash inserted reflexively before I let go
> completely of the other paddle.
>
> The drivers and the finals are not the same as are shown in the Ten-Tec
> manual circuit diagram.  The circuit shows an MRF476 for a driver and my
> radio has an MRF472.  I think there is something coded before the MRF472
> but it cannot be made out.  There is something after the MRF472 and a space
> but its initial coding cannot be made out.  I can see that it does end in
> "12".
>
> The finals are shown as MRF475 on the circuit diagram but my radio has
> 25073 then a space and an M with the rest obscured but the field ends in
> 824.
>
> I have heard that there were changes and substitutes for the drivers and
> finals along the way.  Can anyone give me any info on my situation,
> please?
>
> The rig's signal seems fine.  I have only taken it to 10W so far out of
> caution.
>
> And the last point:  The QSK sounds a bit "sparky/poppy" at times.  Is this
> the way these rigs are supposed to sound?  My SW-40+ and 4SQRP Cyclone 40
> also have these sounds to some extent.
>
> Thank you for any comments that might be made.
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