| G3WRT |
Rating:     |
2021-02-13 | |
| Heavy in more ways than one |
Time Owned: more than 12 months. |
I have had my DX100 sitting on my desk, together with the SB-10, for several years now. In fact, I lifted it there and now I cannot move it without risking a hernia. So, to earn its bench space keep, I am proposing to do the renovation on a slippery bench covering – what to use I have yet to decide. That includes reverse engineering the mods made for the SB-10. I would not subject people to that SSB or knob twiddling – although it might be interesting. There is a wave of AM (not SSB) nostalgia going on now and I am happy to join it. Even though my IC7300 produces excellent AM, undoubtedly intrinsically better than the DX-100, there does appear to be a demand for the old rigs to be aired. I would not be without a decent modern RX though!
I shall never again be acquiring any military/old gear on account of its weight. However, the DX100 with its excellent manual is already resident here and once I locate a place to buy high wattage resistors and high voltage capacitors and spare valves, which I notice are far from cheap, then I will be fair set. I no longer drink so that is one risk I will not have to worry about when playing with lethal voltages. So, it will be warming the shack before long and the next sunspot cycle where I hope to be on 10m and enjoying the rolling QSB across the pond. I gather an 813 is a far better shack heater than 2 x 6146 but that would be major surgery. I may have to fit a block and tackle to the ceiling in order to move it around the bench while working on it! Do I drill the front panel and have individual meters for the grid, anode, volts and Mod. and get rid of that silly switch? and fit a decent microphone socket? DDS, speech processor, replace KT88 with 807 so I can watch the blue beam tetrode on modulation peaks, that means a viewing window or change the steel box… Etc. etc. I am fitting a decent mains socket on the back and getting rid of those awful wound RF chokes and replacing that (let us face it) mess with a decent mains filter. That is not negotiable. Jobs to do in lockdown COVID-19.
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| KG8LB |
Rating:      |
2015-05-27 | |
| Save your DX100 for me |
Time Owned: more than 12 months. |
Don't waste you valuable time on a transmitter that only rates a 3 from the "experts" . . You can send your 6146 B to the expert and send me the transmitter . They work well on CW and AM here .
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Earlier 5-star review posted by KG8LB on 2009-06-10
This is a very nice transmitter. Easily serviced and employs quality components from end to end. The VFO is quite stable as is the general tuning and loading. While the audio is quite good as designed, modifications are easil made to better suit the requir3ements of individual operators. The DX-100 and 100B have one area in paricular however that should receive regular attention. The tube bases of the 5R4G rectifiers are operating at fairly high voltages. It is best to keep this area free of dust and grunge that may find it's way there. Dust can hold moisture from the air under conditions of high humidity and has been known to cause flashover at the socket pins. Another contributing factor is loading the finals to a lower current value than the factory calls for. The same conditions apply to the Apache at both the modulator and rectifier sockets. Keep them clean and operate at suggested loading values. BTW , Light loading and high audio drive values are hard on all of the high voltage components. The mod transformer sees voltages far above safe values especially with that 50+ year old varnish.
All in all a very good transmitter to enjoy vintage AM with. |
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| W8JI |
Rating:    |
2014-02-25 | |
| OK for its era |
Time Owned: more than 12 months. |
The DX100 is OK for its time. I still have a few of them here. It does send CW and has an internal VFO. As others have mentioned, it has CW keying issues that would be unacceptable today. It has two audio coupling capacitors on the plates of the 12AX7 that are too small, making it a bit tinny, but it is simple to change those 510 pF audio coupling caps to .005 or slightly larger parts.
I modified my CW keying with semiconductors to be a sequenced keying with wave shaping, and set the clamp tube carefully, and it cleaned up OK. Took a few hours and cost less than $20 in parts, and now the key is 5 volts!
I've never had a lick of trouble with any 6146 type in any of my rigs, but that's OK. Please save all those nasty rotten unusable 6146B's for me!!!! They won't work for you. |
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| W5XJ |
Rating:      |
2014-02-24 | |
| The King of AM or at least the duke... |
Time Owned: more than 12 months. |
I got my regular DX-100 (not the B model) from a friend here in North Texas after I cut my teeth on the DX-40. This thing is a monster and weighs 100 pounds so be sure you have a good breakfast before you tote it in & out. New caps, a decent power cord with fuse, and some cleanup and I was in business. I use a crystal and the VFO too.
This beast is powerful and has great audio too if you use the right mic - most agree the mic of choice is a D-104 with crystal element sans the preamp if yours has one. www.rbmicro.com sells a great replacement crystal element for the D-104 and it works.
You can still find the two 6146 or 6146 A tubes you'll need for about $20 - $30 each NOS. Don't use 6146 B model tubes only 6146 or 6146 A tubes. There are tons of mods on the interweb if you want to get your soldering iron dirty too.
Have fun but be sure to mind the HIGH VOLTAGE while poking around with the case off.
73 & good DX |
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| K7PP |
Rating:      |
2011-06-12 | |
| 100 Lbs of Nostalgia |
Time Owned: more than 12 months. |
I saw this thing on E bay and my mind flashed back to 1959 and the monster taking up most of my modest desk at my parents home. I had just passed my General and had saved my money and purchased one of these units instead of the Viking Valiant I really wanted. I wasn't disappointed. The Heath cranked out plenty of power and did a pretty respectable job on CW.
Last year I had reached my 67th birthday and something changed. I started buying all the old equipment I always had wanted and after that, all the old equipment I used to own. I think it's an age thing.
Anyway, once home and out of the cabinet, I was amazed at how clean the old Girl appeared inside.
It hadn't had power applied in many years so I just bit the bullet and changed all the electrolytics and a few bypasses, checked the tubes and added a three wire cord.
The unit put out full power and was stable. Couldn't ask for more.
Now, after all these years, I noticed the shortcomings I was happy to overlook when I was a kid.
Who designed the knobs? Cheeeeeeesy!!!! Aluminum set screws in plastic???? Holy Cow!!!
I've got some similar knobs coming that will be much nicer and will save the originals in a box for the next guy that gets it.
Modulation is an issue.
Like the Johnson gear, the modulation sounds like it's coming through a mile long beer can.
There are a few fixes for that.
100% modulation is suppose to occur at around 125 ma. which is below the bottom 1/3 scale of the meter. If you're not running with a modulation scope you might be tempted to run a bit more audio. Big mistake.
At 150 ma peaks the DX 100 will anoint the spectrum with splatter for a couple of megacycles in each direction.
Sidbanders haven't forgotten the treatment they got in the late 50's and early 60's from the AM crowd and are more than happy to point out a wide signal to a careless operator.
That being said, a bit of care and perhaps an hour of warm up will be all that is needed for the DX 100 to shine like it did half a century ago.
I'm having a blast with mine. I just saw one go on Ebay for around 150.00. Lot's of bang for the buck.
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| K6LO |
Rating:      |
2009-10-30 | |
| Solid Iron |
Time Owned: more than 12 months. |
| I had one, borrowed from a friend (thank you N0SP) that I used on 160 'phone many years ago. Somehow it followed me to my present home after college. It sat, taking up space, placing firm, confident, depressions in my radio room carpet as I moved it out of the way of various projects. One day I decided to assemble a vintage AM station on my op desk, pairing the DX-100 with an old FRG-7 reciever, and I lifted the DX-100 up on to the desk. A week later my back recovered sufficiently to hook things up and run it again. I played with it on CW and AM for some time and enjoyed the vintage experience. It was stable, reliable, and a welcome room addition on winter evenings. After about a year of that, it again went back to several years of carpet depression duty. I recently remodeled my home, and needing to clear things out of the radio room, contacted my friend the owner, a corporate pilot, and asked him if he needed an extra heater for his Colorado ham shack. We loaded it aboard the company jet, and I watched the Falcon 2000, taking two hundred or so yards more runway than normally required, lift the big beast homeward. It now sits in Colorado, making firm, confident, depressions on HIS radio room carpet. |
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| HFRF |
Rating:     |
2009-10-12 | |
| Ball buster |
Time Owned: more than 12 months. |
For a Heath manufactured radio it was built to last through a war unlike their later products. I had back problems lifting this thing when I was in my teens. However, this transmitter worked well and had pretty good audio if you liked AM. It made a reliable CW rig too. It is true that the VFO drifted, but so did most other rigs made by other manufacturers.
I don't really understand the AM interest hams have today, but this is one of the best transmitters still around that will fulfill your need to transmit AM. And to Heaths credit, they were one of a few companies that used 6146 tubes instead of those idiot sweep tubes used by other companies. |
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| KQ6IG |
Rating:    |
2009-10-12 | |
| Works |
Time Owned: 3 to 6 months. |
| The Heathkit DX-100 works as it was designed. It was designed to be an inexpensive ham transmitter with some of the features (all band, 100w out, etc) of more expensive rigs. However, it lacks shielding around the final compartment, uses cheap war surplus 1625 modulators, lacks PTT, and uses the legendary awful Heathkit friction drive VFO. If you can make due with some of the general cheapness of the transmiter, it can be an easy inexpensive way of getting on AM. DX-100s are available, low cost, and easy to make sound good. |
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| KB8QEN |
Rating:      |
2009-09-24 | |
| 50 + and going strong |
Time Owned: more than 12 months. |
| No rose tints here, Have owned 10 of these over the years. I presently own a pair of them and use them regularly. Over 50 years old and still going strong, not a memory, actually STILL usong them. A few were re-kitted and re-assembled as winter projects. Not from any shortcoming of the design but to un do some of the silly "improvements" that were made by second guess "engineers" over the years. Like any thing else rating are usually given within their own class of peers. This group is after all VINTAGE TRANSMITTERS...Yes like most others I rate it a FIVE. |
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| G4GZG |
Rating:    |
2009-07-11 | |
| take off the rose tints !! |
Time Owned: more than 12 months. |
I had a DX 100U back in the 1970s when I was a poor student and newly licenced. I ran CW on it as there was no Ham AM activity in those days. Power output was great and the rugged power transformer pushed out the full 750V at full loading. However the rig benefitted from some substantial mods that I did and which others may want to consider. These were:-
1. Grid Block sequenced keying to get rid of the chirpy/ clicky keyed VFO signal - this made the DX100 sound like a Drake, before it sounded like Donald Duck.
2. Better VFO stability, I spent hours on this and found that replacing the grid resistor in the VFO with a 2W dissipation one , and loosening the coupling from tube to tuned cct really improved the VFO stability, which wasn't great. At fors tthe VFO would drift abt 3Khz in the forst hour then 1 Khz per hour after. I got it down to 1 Khz in first hour then a few hertz for the next 5 hours .
I ended up with a very heavy much loved shack warmer that I worked my first real DX ( VK, W etc)on. I also learned lots about valve transmitters too.
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Earlier 2-star review posted by G4GZG on 2001-08-27
I had one of these rigs as my very first transmitter when I was a poor student back in 1978.
The design is fairly basic, VFO/ Buffer/Driver/ Final using 6AU6, 6CH6, 5763 and 6146 tubes, and modulated ( in the UK version 0 by a pair of KT88 tubes , but think they were 1625s in the US version.
It never let me down, always remained stable despite my novice attempts at tuning up,but has one big fault.
The big fault on CW is the keyed oscillator - -this is very difficult to get right, and either chirps or clicks. Also it was a great TVI producer due to the non shielded final stage.
Also the VFO drifted like crazy, even for a tube VFO - -I ended up rebuilding mine with sequenced keying and Grid block keying of the Final and it was much better.
I worked a lot of stations with this rig and they were quite common, even in the late 70s. I also built up my muscles carrying it it about ( over 100lb), made new radio friends and temporarily alienated my neighbours - and learnt a lot about curing harmonic based TVI.
I never used AM cos you didn't then -- SSB was all the rage and the nostalgia thing had'nt happened then .
Mine sat in a corner for 20 years and I sold it last year at a hamfest.
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