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SX 100

Discussion in '"Boat Anchor" & Classic Equipment' started by K7OEG, Nov 8, 2018.

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  1. K7OEG

    K7OEG Ham Member QRZ Page

    I sobained an SX 100 and it worked just fine until I used contact cleaner on the switches. Now it only receives a station in Ft Worth on 820kz which is exactly 1/2 the freq of the IF amp. Anyone got any ideas where to start looking? K7OEG
     
  2. K9STH

    K9STH Ham Member Volunteer Moderator QRZ Page

    OEG:

    Not quite 1/2 the 1st i.f. frequency, but close. However, that has nothing to do with the fact that you can receive WBAP. The WBAP transmitter is just a few miles from your house and the station is running 50,000-watts output! You probably could receive that station with a diode across a pair of headphones with a 2-foot piece of wire attached as an antenna!

    What did you use for contact cleaner? How did you apply the contact cleaner? How much cleaner did you apply to the switches?

    I would closely examine the switches and make sure that all of the contacts are "making". It is very easy to bend a contact so that it no longer makes good connection to the wafer that rotates. You also need to make sure that each wafer is clean with no corrosion, discoloration, etc.

    I use either Goddard's Silver Dip or Tarn-X to clean contacts and wafers. This solution has to be applied using a cotton swab ("Q" Tip) and rubbed across the wafers. Then, allowed to dry for several minutes before applying power.

    Also, have you replaced all of the paper capacitors and electrolytic capacitors in the receiver? These are going to be leaky and can cause all sorts of problems.

    Make sure that you haven't broken any leads from the antenna all the way through the i.f. sections. If you are not very careful, it is possible to do all sorts of damage inside the receiver when working on the receiver.

    If you used too much contact cleaner, it is possible that the switches have physically expanded and then all sorts of problems are going to happen.

    Glen, K9STH
    Richardson, Texas
     
  3. K7OEG

    K7OEG Ham Member QRZ Page

    Hi Glen,
    Ron here, I used Puretronics Extra Strength It might have spray cleaned too much and the residue might have clogged up the works. I will attempt to clean them with the q tips. Also it had a modification attached across the coax connector it consists of two IC's one is a MLC339 and MCL332. the SK who owned it was an RF engineer so he liked to improve things. I removed that mod.
    I should have left well enough alone. It worked perfect until I started to clean it up. It only receives WBAP on the lower SSB setting and no antenna.
    I appreciate you help, I have all the test equipment SG VTVM etc so I will try and start at the audio and work backwards.
     

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