Drake 2-NT Transmitter Re-Cap

I really love the older “Vintage” ham radio gear.   I especially like the Drake radios.  Drake produced some really fine radios, but went out of the Ham Radio business in the 1980’s. The radios are still great radios and perform nearly as good as some of the very latest ham radios made today.  In particular I find the 2-B to be an absolute wonderful CW (Morse Code) receiver.  There is something about the receiver’s AGC (Automatic Gain Control, also known as the Automatic Volume Control) that is just hard to beat on CW.  I have had three 2-B receivers over the years.  Not sure why I sold them but I did, and then I wind up wanting another one.  I will try to hang on to the one I have now.

Recently I acquired a “new” addition to the collection, a Drake 2-NT CW Transmitter.  I was always thought that these small “Novice” transmitters were very neat. One of the really nice features of the 2-NT is that it works well with several of the Drake receivers such as the 2-B, the 2-C, and the R-4 series of receivers.   It also has built in antenna switching, receiver muting, and CW Sidetone as well as being able to do semi-break-in keying.  All you have to do to send is hit the key and it switches to transmit and mutes the receiver for you.

Drake 2-NT CW Transmitter

Drake 2-NT CW Transmitter

I wanted to put together a vintage CW station, something that would be what a Novice station of years ago might be and it seemed that the Drake 2-B receiver and the 2-NT transmitter would be a great pair. I was using a Johnson Ranger with the 2-B for CW, but the Ranger is a very big and heavy transmitter for a 75 Watt (power input to the final amplifier stage) novice transmitter.  Plus, it was clunky to operate, it was not setup for semi break in keying.  Now, I like vintage, but let’s get real, I want to be able to actually use the rig the way I am used to working CW.

After checking out the 2-NT I found that there was a little hum on the transmitted signal.  This transmitter is close to 40 years old, and in these older radios one of the things that needs attention, besides the tubes, is the Electrolytic Capacitors.  The electrolytic capacitors are used as power supply filter caps, so when you see hum on the signal you can bet that the caps are going bad.  The electrolyte in the capacitors drys out over the years and the filter caps don’t do a good job of filtering the rectified AC power into pure DC voltage.  So I decided to “recap” the 2-NT with new, fresh, electrolytic capacitors.

Most of these older rigs used what were called “Can” capacitors.  The can contained several large value capacitors in a single chassis mounted aluminum can.  (I.E. the name Can Capacitors)  With the advent of solid state electronics these high voltage can capacitors have gone away.  They can be had from specialty suppliers like Hayseedhamfest.com, but they can be pricey.  Since there was plenty room under the chassis for axial leaded capacitors,  I elected to go with them for this re-cap.  They work just as good and without pulling the bottom cover off the radio you would never know the difference.

Here is what we started with:

Befor

Before – Click on image to see a larger version

There are three capacitors in the can, a 60 uF for the “bottom” half of the voltage doubler for the High Voltage supply to the final, an additional 40 uF for the low voltage filter, a 20 uF for the screen voltage supply for the final.  There are a couple of axial leaded caps, one 60 uF 450V for the “top” half of the voltage doubler and a smaller 20 uF cap for the negative bias supply.   In shopping for caps, I found that you can’t always get the exact replacement.  I had availability of 80 uF for the HV and LV supply, (originally 60 uF) and 22 uF to replace the original 20 uF caps.  I ordered the caps from Mouser.com and had them in two days.

The can capacitor has lugs on the bottom that are very convenient for wiring, the leaded caps needed something to be wired too.  So, I added two terminal strips.  The first one I soldered to the chassis where the cap ground leg was soldered.  That strip had one ground, and three open terminals.  I moved the original wires from the can to the open terminals then wired the axial caps to them.   I added one more ground terminal under one of the screws for the power transformed and wired the ground end of the 40 uF and 80 uF caps to it.  The the final cap was the 22uF for the bias supply, the positive side goes to the ground on the 4 terminal strip and the negative lead to the circuit board where the original cap was wired.

So, after it is wired up this is what we have:

After - Click image to see a larger version

After – Click image to see a larger version

One final thing, on the cap for the “top” of the voltage doubler the capacitors case is at +300 Volts from ground.  The new caps have a very thin plastic coating on them and I felt that the coating my break down under that voltage where the metal clip holds the capacitor.  So, I trimmed a small part of the original cap’s cardboard cover and slipped it over the new cap where it contacts the metal clip.  Just to be safe…..rather than sorry.

I double checked my wiring, did a few checks with an ohmmeter tests just to make sure I had everything wired correctly and then turned it on.  It worked great.  The power supply hum was gone and it has a nice clean signal now.  The ole 2-NT is ready for many more years of service on CW.

Here is the “new” novice CW station:

Novice Station - Click on image to see a larger version

Novice Station – Click on image to see a larger version

On the left is the Drake 2-NT Transmitter, in the center is a Hallicrafters HA-5 VFO (late 50’s vintage), on the right is the Drake 2-B Receiver and the Drake 2-BQ Speaker and Q-Multiplier.  This novice CW station is much nicer than my original novice station back in 1965, which consisted of a Knight Kit R-100A receiver (that I built as a kit) and a homebrew (home built) 75 watt transmitter.  The transmitter had three tubes, was built into a black wrinkle finished Bud Box purchased from Allied Radio.  Looked right out of the late forties!

If you are into CW, check into the Sunrise Net on 7.123 kHz.  The Sunrise Net is a daily CW net that starts at 1300 UTC seven days a week.  QNI and say GM to the net!

8 Comments so far

  1. drjim on March 6th, 2016

    Big fan of Drake gear here!

    I’ve got an R4-B and a TX4-B, along with most of the accessories (speaker, power supply, C-4 console) that’s my #1 Boatanchor Station. I’ve always like the Drake “4-Line” since I first saw the cool blue dial lights back in high-school.

    I’ve recapped all of it, did a careful alignment, and they’re just wonderful radios.

    I’ve also got a TR-270 VHF/UHF transceiver that was their last ham rig. That one has the internal 1200/9600 Baud packet modem (a repackaged PK96), and the demodulator for wefax and wxsat use.

  2. admin on March 6th, 2016

    I have a T-4XB and the R-4B also. The T-4 is getting it’s finals replaced with 6146s. I know, I know, it isn’t original anymore, but at least I will be able to tune it up without melting down those expensive and rare sweep tubes!

    Looking forward to getting them back on the air soon. Right now I am using the R-4B as the second receiver on my TR-7. Hooked up the external receiver antenna and a mute line to the R-4. It works very well.
    73s

  3. drjim on March 7th, 2016

    A TR-7 is on my Ham Radio bucket list!

    Never had any problem getting the TX tuned up and loaded into the antenna. In my experience the sweep tubes are pretty forgiving. Plus I have a boat load of them I bought years ago.

    “Hayseed Hamfest” has new production twist-lock cans for most older radios now. That’s what I went with for my Drake radios, and also my Hallicrafters SX-117/HT-44 rigs.

  4. SiGraybeard on March 7th, 2016

    Cool stuff. My only vintage radio these days is a Collins KWM-2. At one time, I had an S-Line station as well (S3).

    Does the 2-NT suffer from any of the wax paper caps, or other junk caps that older rigs have?

    I re-capped my R-390A some years ago, on GPs, after an electrolytic let go. I replaced it with a dipped tantalum, about 1/20 the size of the original. Such a common rig has guys selling kits of caps so you don’t need to fill your shopping cart at Digi-Key or Mouser with 25 piece bags of 25 different values.

  5. admin on March 8th, 2016

    SiG,
    No, the 2-NT doesn’t use any of those wax/paper caps, fortunately. Everything except these electrolytic caps were of good quality and in good shape. The last one I have to do is the 2-B, and it doesn’t have a problem with any hum so I have not been in a big hurry to re-cap it. I just put a set of tubes in the 2-B. It developed a problem with not muting all the way. It turned out to be the mixer tube not allowing the AGC line to go fully negative. Some related this to a secondary emission issue on the 6U8 grid. I changed the tube and now the receiver will mute completely. So, when the big EMP comes, look for me on CW!

  6. Dave Stepnowski on April 4th, 2022

    Same station that I have here and I love it. New to me the summer of 2021. Also I was given a T-4X & R-4B by the same ham. Still learning about them. Dave KC3AM 4-4-22

  7. James E. Smith on September 22nd, 2022

    Hi- Just did a re-cap of a Drake 2-NT. Your pix and info was very helpful. I did similar with individual caps. Probably a little easier to by a new can cap, but unit works great now! So on to my next project, Hallicrafters SX-101a and Ht32b.

  8. admin on September 23rd, 2022

    James,
    Great on getting the 2-NT recapped and up and running. The SX-101 and HT-32 will make a nice station. I had a HT-37 that I used for many years and it was a great transmitter. I used it with a R-390 receiver, so I didn’t have to worry about the desk blowing away in a hurricane!