UPGRADING DRAKE GEAR ---questions.

Discussion in 'Ham Radio Discussions' started by K5FRH, Feb 1, 2020.

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  1. K5FRH

    K5FRH Ham Member QRZ Page

    Thanks to everyone who gave me excellent advice on upgrading AC3 and AC4 PS.

    Now I would like to ask if there are key components (capacitors, resistors, etc.) in the T4 series or TR4 series that should automatically be treated as suspect when doing a complete upgrade. I am referring to anything outside of the Power Supplies....ie inside of the radios themselves.

    Again, if there are links where this has already been discussed, please point me there.

    Thank you again, Rod, K5FRH
     
  2. WA1GXC

    WA1GXC Ham Member QRZ Page

    Rod, answer is yes. Lots of info-- Punch-up "Forums" at top of QRZ home page, go to "Technical

    Forums" page -- go to "Boatanchors"-- Put "Drake" in search box and find long history of

    questions and advice.

    In summary-- Specific transmitter resistors always drift high, paper caps and electrolytics

    always need replacement; transistors from early days fail.

    Lots of work to do; not over your head--take your time and be methodical.

    G L !
     
  3. K5FRH

    K5FRH Ham Member QRZ Page

    THANKS AGAIN.
     
  4. WA4NJY

    WA4NJY Ham Member QRZ Page

    Check the WB4HFN web-site. He does repair and has a ton of resources.

    Ed
     
    K5FRH likes this.
  5. KI3U

    KI3U Ham Member QRZ Page

    K5FRH wrote :

    " Now I would like to ask if there are key components (capacitors, resistors, etc.) in the T4 series or TR4 series that should automatically be treated as suspect when doing a complete upgrade. "

    This ought to be of interest :

    Fixing the Drake TR-4 death-trap Neutralizing Capacitor

    Berj / KI3U
     
    KA4DPO, K5FRH and WA1GXC like this.
  6. WA1GXC

    WA1GXC Ham Member QRZ Page



    Berj, thanks for taking the time to develop that well-written piece about the neutralizing cap.

    Looks like you got nailed by a random failure-- luckily, I've never had a problem with that component.

    TR-4C plate meter-- me, too and no fix other than hitting the meter face while I'm tuning-up.

    I've posted note on "Boatanchors" under prior TR-4C Neutralizing Problem comments.

    TKS
     
  7. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    Rod, get in touch with this company https://hayseedhamfest.com/collections/drake and replace the electrolytics. These people are great to work with and have exactly what you need. This will really clean up the transmitted audio.
     
    K5FRH likes this.
  8. KI3U

    KI3U Ham Member QRZ Page

    WA1GXC wrote :

    " Looks like you got nailed by a random failure-- luckily, I've never had a problem with that component. "

    When you look at the TR-4 circuit you can see there is no worse place to install a flawed component than C-76.

    I think inevitable failure is a better description of C-76 than is random failure - what I mean is that random sounds like most C-76's will not fail.

    My original C-76 was constructed without a stop-pin on its rotor, but just relied on the cheap build of an aluminum collar friction fitting on the brass rotor shaft, and this C-76 is mounted right next to the three hot power tubes. So even if the rig is kept in a room of constant temperature for decade after decade, nevertheless each time the TR-4 is powered up and down, C-76 will experience thermal cycling, and the different thermal expansion coefficients of brass and aluminum will stress the metals, and the weaker aluminum collar will get it worst. Failure is inevitable, being to a large extent dependent upon the number of thermal cycles in the rig's history - and that number is for all practical purposes unknown for the average rig changing hands, in addition to the matter of - did the rig always have good ventilation, and was an external fan installed ?

    This is just my opinion : if someone is serious about owning and operating a TR-4 (and possibly the T-4 series has the same flaw) then the potentially catastrophic flaw in the construction of the neutralizing capacitor must be addressed. It takes only a few minutes to check the construction of the neutralizing capacitor.

    Berj / KI3U
     
    WA1GXC likes this.
  9. K9STH

    K9STH Platinum Subscriber Platinum Subscriber QRZ Page

    If you want to keep the original "look" of the unit, then getting replacement electrolytic cans from Hayseed is fine. However, they are also expensive. Installing separate capacitors, under the chassis, is MUCH cheaper, often less than 20% of what the cans cost.

    Glen, K9STH
     
    WA1GXC likes this.
  10. WA1GXC

    WA1GXC Ham Member QRZ Page


    Tks. I need to open up a few cages.


    I was mistaken about your capacitor--it clearly has "ASP" molded into the stator ceramic so is not

    a Hammarlund-quality component. I went into my mid-1960's Hammarlund capacitor

    catalog; I had always assumed "APC" and "MAPC" were registered trade-marks of Hammarlund.

    Perhaps it is so and others have appropriated the "MAPC- and APC-style" as a generic designation.


    Your point is taken and until I open everything up to confirm what's going on, bears consideration.

    It would not surprise me at all if during different production blocks, various suppliers were contracted

    for components. As you noted, all kinds of non-documented changes to component values during

    product production life.

    73
     

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