FT-101E Intermittent Audio level/S-Meter level

Discussion in '"Boat Anchor" & Classic Equipment' started by KB3GWQ, Jun 26, 2018.

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  1. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    I thought that the preamp setting is only relevant to 20m and lower because at 40m and higher it typically increases the noise without necessarily enhancing the signal.
  2. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    I went ahead last night and dialed in 6VDC to 6.00VDC dead-on. I figured if it doesn't really make that much of a difference anyways, setting it to make some people happier won't hurt anything.

    In any case, there hasn't been that much of a change as far as I can tell. It's drifted about 175hz up from a cold start running for about an hour with no heaters, and drifted about an additional 25hz after the heaters were on 30 minutes.
  3. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, setting the voltage to exactly 6V really won't make any difference to the drift. (you WILL need to re-adjust your Tx/Rx pot though)
    That may well be the case . . .

    But if you want your S Meter to read correctly (on ANY band), you need to leave the "Pre-Amp" on !

    Generally, as I have fairly efficient Transmitting antennas, the reports I get are the same as I give. However, if I ever my report is way down on what I am receiving the other station, I ask them if they have turned their rig's Pre-amp off . . . when they turn it on I then receive a proper signal report!

    Roger G3YRO
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    Every one of those double sided connections need to be repaired.

    That was a fault on many things when double sided PCB was starting out.

    The feed thru was the #1 problem for intermittent connections.

    Always make sure your DC power supply has the correct voltage and no ripple before adjustment.

    Have Fun.
    Last edited: Jul 18, 2018
  5. G3YRO

    G3YRO Ham Member QRZ Page

    I've had to re-do DOZENS of solder-through connections on my Kenwood TS-930S . . .

    But I have NEVER known this to be a problem on ANY FT101 boards !

    Roger G3YRO
  6. KB3GWQ

    KB3GWQ Ham Member QRZ Page

    I had to readjust the zero offset pot a little bit, but it wasn't a whole lot of change from 6.32 to 6.00. Either way, just to satisfy everyone else for these tests now it's at the voltage they want in the manual.

    OK, on the preamp then I guess it's pretty accurate when you consider the preamp. I practically never use the preamp, It's mostly unnecessary (imo) for CW work.
    KA9JLM likes this.
  7. G3YRO

    G3YRO Ham Member QRZ Page

    Oh I'm sure . . . just that all your Signal Strength Reports will be misleading!

    It's a shame they don't have circuitry to make the S Meter still read correctly when the PreAmp is off. (that would be quite easy to do on modrn rigs)

    Roger G3YRO
  8. HS0ZED

    HS0ZED Ham Member QRZ Page

    Elecraft K3 has SMTR MD that can be set so S meter readings stay the same irrespective of preamp/attenuator settings.

    Much happier with the S meter response on the FT-101E here now it has a new pot on the IF board. Still feel the receiver is plenty hot enough. Backing off the RF gain until the S meter is just lifting on the band noise is much better. As has been noted, and with the exception of the various pots, component quality seems very high throughout the rig.
  9. G3YRO

    G3YRO Ham Member QRZ Page

    You have to bear in mind that those skeleton pre-set pots was all there was available in the 60s (when that rig was designed). Swapping them for the Cermet multi-turn ones is a worthwhile mod, and very easy to do (given that the boards are all plug-in)

    All the main switches and pots are high quality . . . I've never had to replace any in any FT101.

    Roger G3YRO
  10. HAMHOCK75

    HAMHOCK75 QRZ Member

    I went through the schematics for the reg/calibrator boards for fun. Here is what I found. The calibrator amplifier in PB1179, PB1185 is the same design. It changed in PB1314. The gain was increased.

    This is the amplifier in PB1179 and PB1185


    This is the amplifier for PB1314


    The reference designators have changed but the parts are all the same except for the value of the emitter resistor which dropped from 100 ohms to 56 ohms. Roughly speaking this change increases the calibrator output by 6 dB assuming the amplifier is not saturated. That does not justify a change from S9 to S9 + 25.

    I went back to the manuals starting with the earliest plain version 101 up to the F version. This is what I found.

    For all versions though B, the S-meter adjustment instructions are,


    but in the E and F manuals it becomes,


    Clearly this is not true that 50 uV is the same as S9 + 25. G3YRO what do you think?

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