DAK X

[357]

Was wanting to know if anyone can tell me the good and bad things or comments on this radio?

Thanks,
73's
Jay

[Tramfan]

I'm not an expert on these, but from what I've heard they really aren't all that great of a radio. Very impressive looking, but that's about as far as it goes. They are a hybrid radio, which is to say that they are mostly solid-state, but with tube final output. Not really a bad design (my Yaesu and Kenwood use the same design), but with the Dak the execution leaves something to be desired. I'd love to have one myself, but I don't feel they are worth the big prices they bring.

[**GRUMPY**]

John is right. I have a Dak IX, it looks nice on the shelf but not the best of radios that I have. If you look inside of one of these radios, it just a big empty box. The Dak IX seems to be the better one of the two from what I hear, the Dak X seems to have had more issues. If you are looking for an everyday radio, save your money. If your thinking of buying one to use every so often and have your shack look pretty then go ahaead and get one!

[357]

Hey,
Grumpy and John thanks for the reply, I was just wanting to know I am wanting to add to my collection, and the DAK's I see on Ebay are going for stupid money, I have Browning's and Tram's now and love them but was just wanting to know before I laid down some cash on one , would rather spend my money wisely if you know what I mean.

Thanks Again Guy's
73's
Jay

P.S.
Grumpy I still love your forum I will start posting more it's been awhile.My job has been keeping me very busy.

[**GRUMPY**]

No problem Jay, glad you are able to stop in!

[Preacherman]

I have a MK X and it's not a bad rig. The weakness on the DAK is the recieve. They WILL talk and are a lot of fun to operate.

I may have Wizard update some of the transistors in the recieve....then it would be a nice rig.
Preacherman

[livewire]

I know this is an old post but I just have to comment. I.ve owned alot of radios just like most of you have,and after 40 some years of this you learn something. My Dak X is as good as any radio manufactured at that time, and better than most. Its how you take care of the radio, how you tune the radio, how you don't over drive the radio. I've heard junk Brownings junk Trams Junk Sonars etc, haven't you?

[Sandbagger]

Nov 15, 2008 22:21:55 GMT -5 livewire said:

I know this is an old post but I just have to comment. I.ve owned alot of radios just like most of you have,and after 40 some years of this you learn something. My Dak X is as good as any radio manufactured at that time, and better than most. Its how you take care of the radio, how you tune the radio, how you don't over drive the radio. I've heard junk Brownings junk Trams Junk Sonars etc, haven't you?

The DAK Mark X is a somewhat unique radio. The meters are nice and large and the radio itself gives off an air of professional quality. But if you really look at the insides what you'll find is that the main board of the radio is a Korean copy of the Cybernet PLL-02a SSB chassis. The same chassis used in Lafayette's SSB radios, G.E.'s, Midland's, etc. It was a decent chassis and it could be frequency expanded all over the place. But it's nothing exceptional. It's a cookie cutter design used by several brands of CB radios back in the late 70's, with the exception of the tube output.

For whatever reason, DAK chose to use a tube driver and final instead of the standard solid state outputs. You can mod these for more power output, but it's better to just run an amp, rather than strain the radio's power supply and other components.

I just got done restoring a Mark X for someone. I liked the large meters and it did have nice clean audio on transmit. But IMHO, it's not in the same league with Tram and Browning.

[Deleted]

Nomad informed me of a complete history. Stay away. Pretty is about the only good thing about them.

[livewire]

I would take nomads advice and leave them alone.who ever he is. more for me.

[Deleted]

Well, he knows what he is talking about, and they aren't any good.

[livewire]

yea yea yea

[2600]

I found an old post from another forum on this subject:

Hmmmm..... So how much bad news can you stand at one time?

Important parts of the Dak ten were radically UNDER-designed. The skinny tube serves as the transmit driver, and the fat one is the final amplifier stage.

The AM transmit modulator is a solid-state circuit. Two small TO-220 audio transistors drive into a
transformer, which steps up the audio voltage to modulate the tube final. Trouble is, this modulator
stage AND the transistor that regulates the 13.5 Volt DC power supply section are ALL THREE bolted
to a tiny piece of half-inch aluminum angle bracket. This is a woefully tiny heat sink for all that power.
If you turn the AM modulation down to around 90% as directed in the manual, it will survive for
around a year before blowing out. Turn it up, and "POOF", the AM modulator and regulator transistor will repeatedly overheat and blow out.

Here is one solution to this problem. A large, metal power transistor gets mounted on a large heat
sink, and three wires are run to the circuit-board holes where the old regulator transistor was pulled
out. Another large heat sink with two oversize transistors serves to take the place of the original
plastic TO-220 modulator transistors. The original driver next to each of these also gets replaced,
each with one the size of the original modulator.




The pic above shows the old and new, side-by-side.


The rectifiers for the 13.5-Volt DC supply are also way too small. A generic 25-Amp bridge rectifier can
be bolted to the side rail of the chassis, alongside where the original rectifier diodes were removed.



Here's a view of the new heat sinks, one for the regulator on the right, and the modulators on the left mounted on the inside of the rear panel.



And this leaves only:
-> The channel selector,
-> Failure-prone channel digits,
-> Numerous electrolytic capacitors that fail,
-> And chronic solder-connection failures to fill in the rest of the picture, so to speak.


Any more rain I can dribble onto your parade?

It's not the years, it's the miles, too. If a radio has little or no wear and tear on it,
the price to put it back on the air will be lower.

A 1977 car won't be a reliable daily driver even if it's "Show Room Mint". Some things just don't last
that long. If the radio has had maintenance and upgrades already done to it, you probably won't
have to repair it more than once a year or so.

And if it's all still "original" on the inside, it'll be a lot more frequent than once a year.

73

[Deleted]

Yea yea yea !

Here is a post from Nomad from the CB Tricks forum on a question I had about them for a friend. I'll take a wild guess and say this is the same Nomad (whoever her is!)

www.cbtricks.com/forum/index.php?topic=893.0

"The M.H. Scott company of Columbia, Maryland sold a line of base and mobile radios. All of them containing one or more borderline faults that would put a radio off the air, or remain 'locked' on channel over only half the 40 channels, or only when you warmed it up. Or only until. You get the idea. Not sure how many mobiles they sold, but all of them were totally forgettable. Looked for all the world like cheap replicas of Midland radios that were being made in Japan. Before long, Midland mobiles that looked just like the DAKs on the inside started appearing on the market. They sucked, too. Never learned who that factory was. The M.H. Scott company launched with 40-channel radios, and never sold a 23-channel model. Went bust along with 90-plus percent of the industry by 1980, more or less.

Mileage is a big issue for one of these. The miles catch up with it in a hurry. It's a short-lived unit that often broke before the warranty was up. Soldering problems are very common. The Korean factory where it was made had not yet learned how to properly make double-sided pc board. As a result, connections made from foil on one side to foil on the other side are forever coming loose and causing intermittent dropouts.

Trouble is, the design is insanely marginal. The factory sent the radio out with the modulation limiter set to about 75% modulation. Legal, but not terribly loud.

The radio has two tubes, but neither of them is an "audio" amplifier. The 12BY7A is the RF driver stage. The mobile-radio pc board at the center of the radio does not have the normal driver and final transistors in it. The 'predriver' stage feeds the 12BY7A through a step-up RF transformer. Your SSB transmit signal passes down this chain to the final tube and then to the antenna.

On AM, ONLY a carrier feeds from the radio board to the driver and to the final. The final tube is high-level modulated by a step-up transformer. The audio feeds into this transformer from two small TO-220-size audio power transistors. They are bolted to a tiny piece of 3/4-inch aluminum angle bracket. Not much of a heat sink.

BUT WAIT, THERE'S MORE ! !

That same tiny piece of angle stock also has the voltage-regulator transistor bolted to it. The regulated 12-Volt DC power needed to run the radio pc board and channel digits from a solid-state mobile radio is also used to power the AM modulator.

So long as the modulation limiter remained at the factory setting, there was a chance that the radio would survive the warranty period before it broke down.

Crank it up, and pretty soon BOOM!

An owner who reached inside and cranked (or yanked) the modulation limiter would be told the warranty was void, and quoted a repair price.

The rectifier diodes on the 12-Volt supply were way too small. Most Mark Xs will have eight diodes in the bridge circuit. Four on the top side of the board, and four soldered to the pads underneath. Even doubled up, they are way too small, to boot.

Worked up a way to deal with the design disaster by beefing up all the stuff that they made too small. A 25-Amp rectifier bridge gets bolted to the chassis side rail. A big metal TO-3 transistor mounted on a heat sink gets wired in place of the regulator transistor. And a pair of the big metal power transistors goes on aother heat sink, with wires leading to the modulator/regulator pc board where the old ones had been mounted.

Got some pics of how this can be done, but I can't log in to my image host right now. Bummer. Can't complain. Doesn't happen often.

Just be very nice to the channel selector. It wears out pretty fast in regular use. Replacements are made from unobtainium."

[Sandbagger]

Nov 24, 2008 9:09:18 GMT -5 @vinnies said:

Yea yea yea !

Here is a post from Nomad from the CB Tricks forum on a question I had about them for a friend. I'll take a wild guess and say this is the same Nomad (whoever her is!)

www.cbtricks.com/forum/index.php?topic=893.0

"The M.H. Scott company of Columbia, Maryland sold a line of base and mobile radios. All of them containing one or more borderline faults that would put a radio off the air, or remain 'locked' on channel over only half the 40 channels, or only when you warmed it up. Or only until. You get the idea. Not sure how many mobiles they sold, but all of them were totally forgettable. Looked for all the world like cheap replicas of Midland radios that were being made in Japan. Before long, Midland mobiles that looked just like the DAKs on the inside started appearing on the market. They sucked, too. Never learned who that factory was. The M.H. Scott company launched with 40-channel radios, and never sold a 23-channel model. Went bust along with 90-plus percent of the industry by 1980, more or less.

Mileage is a big issue for one of these. The miles catch up with it in a hurry. It's a short-lived unit that often broke before the warranty was up. Soldering problems are very common. The Korean factory where it was made had not yet learned how to properly make double-sided pc board. As a result, connections made from foil on one side to foil on the other side are forever coming loose and causing intermittent dropouts.

Trouble is, the design is insanely marginal. The factory sent the radio out with the modulation limiter set to about 75% modulation. Legal, but not terribly loud.

The radio has two tubes, but neither of them is an "audio" amplifier. The 12BY7A is the RF driver stage. The mobile-radio pc board at the center of the radio does not have the normal driver and final transistors in it. The 'predriver' stage feeds the 12BY7A through a step-up RF transformer. Your SSB transmit signal passes down this chain to the final tube and then to the antenna.

On AM, ONLY a carrier feeds from the radio board to the driver and to the final. The final tube is high-level modulated by a step-up transformer. The audio feeds into this transformer from two small TO-220-size audio power transistors. They are bolted to a tiny piece of 3/4-inch aluminum angle bracket. Not much of a heat sink.

BUT WAIT, THERE'S MORE ! !

That same tiny piece of angle stock also has the voltage-regulator transistor bolted to it. The regulated 12-Volt DC power needed to run the radio pc board and channel digits from a solid-state mobile radio is also used to power the AM modulator.

So long as the modulation limiter remained at the factory setting, there was a chance that the radio would survive the warranty period before it broke down.

Crank it up, and pretty soon BOOM!

An owner who reached inside and cranked (or yanked) the modulation limiter would be told the warranty was void, and quoted a repair price.

The rectifier diodes on the 12-Volt supply were way too small. Most Mark Xs will have eight diodes in the bridge circuit. Four on the top side of the board, and four soldered to the pads underneath. Even doubled up, they are way too small, to boot.

Worked up a way to deal with the design disaster by beefing up all the stuff that they made too small. A 25-Amp rectifier bridge gets bolted to the chassis side rail. A big metal TO-3 transistor mounted on a heat sink gets wired in place of the regulator transistor. And a pair of the big metal power transistors goes on another heat sink, with wires leading to the modulator/regulator pc board where the old ones had been mounted.

Got some pics of how this can be done, but I can't log in to my image host right now. Bummer. Can't complain. Doesn't happen often.

Just be very nice to the channel selector. It wears out pretty fast in regular use. Replacements are made from unobtainium."

I've only worked on 2 DAK X's. The first one was back in the 80's and it was a piece of crud. I'd fix one thing, and it would show up a month later with some other issue. But back then, I had no service info for it, and I had less experience to rely on to foresee what the root causes were.

The second DAK X I worked on came my way about a month or 2 ago. Someone of the golder screwdriver mentality had been in it. The channel display was missing segments and it neither transmitted or received. There was a bad 8V regulator on the main board along with a couple of bad small signal transistors. (Due to the actions of the screwdriver tech). The main problem was caused by a bad VCO block. Luckily I had a spare from an old Lafayette Cybernet chassis, which is virtually identical (except Cybernet encased their unit in epoxy). Once that was done, the radio came up and ran fairly well. A good alignment and it received and transmitted as it should. The modulation, as stated before, would not break the 80% mark, so I had to change a resistor in the circuit to allow adjustment to the 100% point, which I then did. The final job (and the biggest PITA) was finding and mounting a replacement LED for it. I managed to find a nice green display and managed to mount it in there. Had to do a little Rube Goldberg'ing to fit it in there as it was not an exact replacement. But the long and short was that this radio performed well, at least for the 2 weeks that I had it. I'm sure the insufficient power supply issues will rear their ugly head sometime i the future. But considering that this radio was close to 30 years old and pretty much all original, with most of the damage coming from previous work done by a "lesser-skilled" tech(s), I really can't complain all that much. I've certainly had to do way more work to get sick Tram D201's back to health, due to age-related failures.

I'm certainly not going to become an advocate for DAK radios, based on my small sampling of them (50%), but I will say that like many other radios (including the RCI-2995) that are victims of poor design, many times you can correct their woes and then enjoy something a little more unique than the typical CB

[SIX-SHOOTER]

I just came across this old thread but wanted to add my 2 cents worth. I currently own (2) of the DAK Mark X & (1) DAK Mark IX & one of the Mark X's is my Favorite all around base CB Radio. I prefer it over my TRAM D201A on AM & SSB & over my Golden Eagle MK IVA on SSB. I have had Zero issues or complaints with it. I have now owned (3) of the Mark IX's & only one of them was a audio Monster on transmit & maybe the loudest I have ever heard or owned of any CB since 1965. I just purchased the 2nd Mark X & the Mark IX yesterday from a friend & they look AWESOME other than one meter cover missing from the Mark IX. I have not plugged them in since my friend said they both need work but he is not a tech & was not sure what amount of work? If all else fails I will keep the 2nd Mark X for parts for my near Mint Mark X since some items are difficult to find for them. The face plates are very clean as are all of the knobs on both of them. My 1st Mark X has no mods & does not have the clarifier unlocked. I like my radios stock other than a Peak & Tune so maybe these two have no mods either. There are no extra switches or holes so I may have gotten lucky & both have all of the original toggle switches & none are broken.

SIX-SHOOTER

[2600]

they look AWESOME

Roger that.

An unmodded DAK is the only kind that survives for long.

73

[mxer746]

Hello, I just happen to be working on a DAK Mark X for a friend. The VCO block is dead. Where would I find one? Thanks guys. I'm new to working on these, I am a avionics bench and install tech for a company here in Columbus, and usually I'm working on Collins Proline, King, and other various aircraft radios. My friend is an old mechanic who uses this regularly.

[2600]

Found some of the VCO modules used by Cybernet on fleabay made by a guy in England. They're just a circuit board with the correct parts and wires protruding where the original module's pins would be. The one in the DAK is a copy of a Cybernet VCO module. Can't remember the part number that was used. Seems to me it started with the letter "Z".

I'll have a look and see if the bench notes at work have that part number. Would serve to narrow down a fleabay search.

Just searched fleabay for "Cybernet VCO module" and got nothing helpful. Seems to me there is a schematic of the module's insides in the Mark X manual at cbtricks.com.

Typical fault is for the tuning slug to get destroyed and seized in the hole.

Like a car. Once it reaches a certain age, the only parts source becomes the junkyard.

73

[mxer746]

I've encountered alot of that with the tuning slugs in the 20 to 30 year old aircraft radios I work on regularly. Thanks for your help.