[Kenwood] Kenwood TS-940SAT S Meter

[brian tempero]

Clif,

Is the instruction for turning on the internal calibrator in the service
manual? I am not familiar with it.

Brian Tempero
HIVE Manager
Stanford University
650-724-8122

From:  Clif <clif at avvid.com>
Date:  Wednesday, February 4, 2015 at 9:27 AM
To:  MarioDaniele Greco <daniele_mdg at yahoo.it>
Cc:  brian tempero <btempero at stanford.edu>, "kenwood at mailman.qth.net"
<kenwood at mailman.qth.net>
Subject:  Re: [Kenwood] Kenwood TS-940SAT S Meter

Easiest way to check is turn on the internal calibrator. It is after the
attenuator relays and leaves them out as a problem. It should read S7-9 on a
properly aligned radio on 20m @ 14.2 in USB. If that is correct and an on
air signal is way low then the attenuator relays need to be replaced. If
it's not S-7-9 a signal calibrated output generator is needed to determine
if the problem is s-meter setting or the rx sensitivity is actually down due
to a problem.

As a note the 940's were aligned to the Collins spec, 50uv = S-9, FWIW S-1 =
1.25uv. The levels in the service manual are different because the SG output
is speced into an open load not 50 ohm.

On Wed, Feb 4, 2015 at 11:06 AM, MarioDaniele Greco <daniele_mdg at yahoo.it>
wrote:
> Hi,
> same "problem" here with my TS-940, one of the latest serial numbers, 9
> Millionxxx. My S-meter moves only when signals are stronger than S5-S6.Some
> typical TS-940  issues are :- S-meter scale is calibrated according to
> Japanese scale, where S1 japanese = S5 in the  Collins USA signal scale.-
> there is a PIN diode attenuator, in RF board,  exactly after the RX input
> filters, before the RF cascode FET amplifier,  that could be out of
> calibration: the reference value is adjusted by VR1 in RF board. See service
> manual for the right values
> - the input attenuator relays could have dirty contacts
> Last, but not least, if your radio is very old, it could be necessary to check
> the whole RF-IF signal chain. The Service Manual is of help.
> Just try this : switch to lower band, 500KHz - 1.5 MHz: if  the received
> signals or noise level is strong, and the S-meter goes to S6 or beyond, this
> means that the at least the signal chain is OK, otherwise it needs to be
> services.Hope this helpes73MarioIZ0IRH
>      Da: brian tempero <btempero at stanford.edu>
>  A: kenwood at mailman.qth.net
>  Inviato: Martedì 3 Febbraio 2015 18:19
>  Oggetto: [Kenwood] Kenwood TS-940SAT S Meter
> 
> All,
> 
> This is my first post. I have a strange issue with my kenwood ts-940SAT.
> Here is the issue:
> My radio receives and transmits very well. The issue is that my S meter
> barely works. If a really strong signal comes in the needle spikes and then
> slowly descends. If the signal is not really strong the needle does not
> move.
> When I transmit the needle works without issue in all settings (power, swr,
> acl and so on).  I have all the knobs set per the operating manual for first
> use. I am stumped at this issue.
> 
> Thank you for reading this issue and all comments or suggestions are
> welcome.
> 
> Brian Tempero
> HIVE Manager
> Stanford University
> 650-724-8122 <tel:650-724-8122>
> 
> 
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-- 
Clif Holland KA5IPF
www.avvid.com <http://www.avvid.com>