SO I got this FT-101E the other day...

Discussion in '"Boat Anchor" & Classic Equipment' started by VA3CQC, Aug 30, 2010.

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  1. W8JI

    W8JI Ham Member QRZ Page

    It could be many things, including the transmitter is oscillating and you are seeing a spurious signal. I hope the tubes you used are original specs, and I hope alignment and neutralization are right.

    The FT101 is not easy to work on, because it is a relatively unstable design even when things are right. Making that worse, component access is limited. Unfortunately, they are trouble enough for an experienced tech to get right.

    As radios started to become modular, they became increasingly difficult to service.

    Something like an old TS520 would be a whole lot easier to work on, and is a whole lot less critical for alignment and stability.

    73 Tom
     
  2. VA3CQC

    VA3CQC Ham Member QRZ Page

    This is my first suspicion. I used GE/Motorola 6JS6C tubes, and what came out were NEC 6JC6C's. Supposedly I have heard they have differing inter-electrode capacitances that make them hard to neutralize. I've adjusted the cap on the underside until "the dip is even on both sides" or "the output power peaks as the grid current dips", as both seem to be the case. It works and it does produce 120w in tuneup and SSB on, say 80meters. The alignment is a bit off, but it can't be that bad because some people mind and some don't. It seems close enough to me at least.

    Yes, but I didn't get one for free... I got this FT101E instead. It's just a coincidence I bought a FT101ZD earlier.
     
  3. W8JI

    W8JI Ham Member QRZ Page

    Alignment has little to do with how others hear you, at least in the context of problems I am talking about.

    Adjusting the dip so each side is even is not the best way to neutralize a rig....but if you do use that method it has to be on 15 meters or some higher band. It should not be done on 80 meters no matter who says it is OK. I know this because I design PA's, and understand extremely well how they actually behave. :)

    The band where neutralization is most important is ten meters. The band where it is virtually meaningless is 160 meters. It is critical you get more than halfway to the upper frequency limit to adjust the balance in the neutralization.

    The problem is this. If the rig is unstable and oscillating, neutralizing by looking at out-of-resonance plate current is often incorrect.

    Regardless of what shape the rig is in, neutralizing by looking at current out of resonance is a terrible way to do it. I would disable the rig and neutralize cold.

    http://www.w8ji.com/neutralizing__amplifier.htm

    If you have a service manual you can go through the rig step by step. I gave away my FT101EE and FT101ZD, but at one time I had both plus extender cards to service the modules. I can't recall if it is possible to get at all the critical alignment points without extender cards, but I think not.

    I wish I could help more.....but I inherited my Yaesu's from a friend who passed away and gave them to aspiring new hams after going through them. I didn't have them more than a few months before loaning them, and then eventually giving them away.

    73 Tom
     
  4. VA3CQC

    VA3CQC Ham Member QRZ Page

    So normally you would apply drive, can you not just hook up a signal generator to the input to the PA and a radio on the output? And you'd tune for minimum noise on the receiver using the neutralizing cap?
     
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