[Kenwood] Kenwood TS-940SAT S Meter

Wed Feb 4 12:48:45 EST 2015

Thanks a lot Clif for clarifying and the suggestion to use the internal calibrator. According to your experience is it possible to find a replacement for the attenuator relays? Mines sometimes give the 10 dB step as 20 dB or nothing.BR

      Da: Clif <clif at avvid.com>
 A: MarioDaniele Greco <daniele_mdg at yahoo.it> 
Cc: brian tempero <btempero at stanford.edu>; "kenwood at mailman.qth.net" <kenwood at mailman.qth.net> 
 Inviato: Mercoledì 4 Febbraio 2015 18:27
 Oggetto: 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

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www.avvid.com