Originally offered in the s, the Dentron GLA was a clever little amplifier. It was compact, reasonably priced, and promised watts PEP. They were an up and coming company and they made good equipment which could easily be described as, "Built like a battleship. I recently dug out my GLA amplifier after having used it only a very few hours. A friend had been looking for his own amplifier on eBay and I had told him several things about the GLA but I obviously had forgotten several items. When I opened my early version amp up to brush out the cobwebs and dust I discovered that mine had the tuned input switch and added PC board.
I vaguely remember removing a small PC board with a single wound toroid core and one high voltage door-knob capacitor and a couple of pieces of small RGsized coax. Seems like at that point I replaced it with the newer tuned input board. Also I remember unsoldering the four tube sockets and reinstalling them on a new board I had received from Dentron.
History of the manufacturer
Since I never seem to throw anything away I remembered I had the old tube PC board in the bottom drawer of my desk. Digging around, sure enough there it was.
In the pictures below I have shown the old board and also the newer board, which is now installed in the amplifier. Note that the new board, added to my original GLA, is marked "GPA B" so this was evidently an offering to original owners to upgrade their amplifiers to nearly the same features as the next model, the GLAB.
I just don't remember. If most other owners of the original GLA have these modifications, it must have been sent to all buyers otherwise it might have just been made available for an addition cost.
Too much time has passed for me to remember that.
dentron rf amp
The pictures below show probably more views than necessary but may be helpful if you have an original GLA and would like to modify yours with features of the later models. Also GI7BT had a. I tried to find the site on the internet where I had downloaded it but was unable to locate it. The file can be downloaded by clicking on GI7BT's tuned input board.
There is the possibility that this board is no longer available from Far Circuits but it would probably be worth checking with them.
Click here. Email to: k5lad arrl. Current PC board2.Electrolytic Capacitor Reforming - Why and How To
Front panel. Inside view of amp. Left side of amp. New on top - orig on bottom. New tube socket board. Old tube socket board. Original PC board. Rear panel. Relay - antenna. RF input. Right side amp. Tube boards comparison. Tube socket - LR - old. Tube socket LR - new. Tube socket UL - new. Tube socket UL - old.When you subscribe, you receive only messages for the product you have subscribed to.
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The site will be something of which everyone involved can be proud to say they were a part. Toggle navigation. Forgot Password. Reviews Home. For the money you canot find a bether one. You have all the room to repair when something goes wrong, and conversation is easy. This is a good entrance amplifier because its not so expensive, and you can convert it with EL tubes, and i have tons of them. A good amplifier doesnt need to be expensive.
OK, I guess. Time Owned: more than 12 months. I wouldn't make a deliberate effort to go out in the world and try to find one of these. It was fine for the day A classic bang-for-the-buck design, but nothing special. Today, you'd be looking at a restoration to at least have the piece of mind that it wouldn't be too gross for your transceiver to feed. Even when new, it was pretty basic It wasn't a quality product at all, and in fact Dentron was the go-to product line when someone was unwilling to purchase something designed and built to a higher standard and with more stout components.
So, if you can find one that's not trash and can't resist owning one, it's OK. Just don't expect much more. It did have a problem when I received it shorted connection to the load variable capit was hidden and difficult to find. After fixing this little gem my TS drives it wonderfully. This little guy has tuned input so the input VSWR is 1.
Kind of wonder if this little guy had the short problem all along and it kept changing hands. The cabinet is in great shape and the well designed front panel makes it a attractive addition to the shack as well as being compact and functional. I also found a GLT tuner to match the amp, the pair make a real great addition to the shack. I bought my dentron glab for I recently purchased an sb my next project its going to be harbaughed I can't wait.
There's my 3 cents on this great little amp. I bought this amp during HamventionI found several of the amps available. I chose and amp that looked practically brand new!!! I got it home, actually read the directions Its my first amp, its easy tune, work great with my Beam and Loop both.QRZ Forums.
Dentron GLAB Tags: dentron glab. Hello Everyone, and thank you for reading my post. I just picked up a GLAB recently and have a few strange things going on with it as follows and hoping you can help. This is with the transceiver in receive, so the amp is not keyed.
I have a GLA first gen which shows no current draw when in the same condition. Also, on 10M the amp puts out watts and this is with my radios antenna tuner engaged and the radio driving the amp at 80 watts or so, but on the other bands the amp puts out roughly watts. Not sure if these are related, or something completely different. Any insight is greatly appreciated. Thanks Again! First, someone must have added the 10m modification kit, since the base model covered only 80m - 15m.
But I know Dentron did offer such a kit. Possibly there are wrong or failed components in the 10m section. The power resistor in your photo appears to not connect to anything on one end, and I have no guess why it's there.
PM-2500 Replacement Power Supply Module for MLA-2500
It also appears someone changed the output coupling capacitor C11 as there's a splice in that wire that's not normally there and the original capacitor was a doorknob type that doesn't seem to be showing in your amp.
Should look more like this; If the amp is drawing current in standby, either D1 is shorted or the wrong value, or you have a bad tube or tubes. Hi Steven. Thanks for the reply, and direction on the current draw issue. As for the C11 cap, the original one probable failed and the previous owner installed the replacement.Dentron MLA Repair. It had spent many years in storage at the department of electrical engineering at U.
After all, given the attitude of the EE department toward all things electrical whether they belong to them or notthey probably would not have given it back if it had worked. No documentation came with the amplifier. Thus "control" over club hardware and club space has been spotty at best. Be that as it may there remains a few dedicated people who try to keep things going, despite the University beauracracy's attempts to kill the club.
As of early the club's website is down, and I haven't heard from anyone connected with the club for months. The unit fired up, tuned, and ran fine, although the output power seemed low at an indicated W. We had no manual at the time so we assumed that the unit wasn't built for more than W out. A watt meter, which measured beyond W, was not available. It was surmised that the folks at EE may have tried to drive the thing at signal generator type levels. Such a power amplifier requires far more drive than a signal generator can produce, if it is to amplify effectively.
Perhaps they also neglected to toggle the relay port to put the unit in Transmit mode. Who knows. In any case the unit worked fine. Work of Feb Several years ago the University FM Facilities Management crew plowed one of the windows open during winter snow removal. This deposited a quantity of dust and dirt on much of the bench space, as well as the equipment.
How much water ran into things is not known. The discovery of the window being open was long after the fact. Given the high ambient temperatures in the shack, it wouldn't take long for the snow to melt and then evaporate, even with the window open. It also appeared to some that the unit may have some sort of fault. The amplifier spent a good deal of time in this undetermined state. At length, AA1ZB offered, and undertook, the cleaning and checkout of the unit.
Unfortunately this ended up taking many, many months due to other commitments. One of the more obvious differences between the two versions, is the way the two valves have their Cathodes tied together. On the MLA the two Cathodes have an anode to cathode diode pair connecting them. In the MLAb the Cathodes are tied directly together with no diode pair. The two versions also differ in some of the connections of their respective Grounded Grid implementations. Since these differences did not involve the broken RFC, it made little difference which version the unit was.Discussion in ' Amplifiers ' started by GAMay 19, WorldwideDX Radio Forum.
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Share This Page Tweet. Your name or email address: Do you already have an account? No, create an account now. Yes, my password is: Forgot your password?The Heathkit Shop Keeping the green flame burning. Denton was known for making antenna couplers as well as RF amplifiers. Their day in the sun came and went, yet there are thousands of these amps still on the air.
Totally different, yet the same. Since both of these amplifier are long in the tooth, their power supplies have worn out. Specifically, the high voltage capacitors. I offer two solutions. Clipperton L page. This supply upgrade is not hard to install, but can be a challenge.
Take plenty of photos, notes and drawings. The relay shown in the photo below is not factory. It's a modification to change the operating bias on the tubes in standby condition. This allows for the tubes to run cooler and thus have a longer life. The Dentron GLA amplifiers are just as popular now as they were in the late 70's. They run four sweep tubes and can produce about PEP input on sideband. On CW, you can see about ish watts, depending on the band and the quality of the sweep tubes.
Although the tubes are expensive, if properly tuned, they will last a long time. The power supply, however, maybe the weak link. Nothing fancy, the original power supply is now over 30 years old. The capacitors have dried out, the other parts may have been stressed beyond a useful life.
This upgrade has it all. New double sided pcb with all new components. The diodes are over rated, 3 amps at vdc, and the capacitors have twice the amount of capacitance as the original ones.
The meter shunt is now 5 watts instead of the factory 1 watt unit. I've placed glitch diodes to prevent meter damage. The resistors are all flameproof and most are three watt units. Even the low voltage control circuit has improved components. The upgrade comes assembled. The instructions are thin, on purpose, as a novice shouldn't be inside this amplifier without proper knowledge.
The voltages inside will kill. I have received a note or two that the voltage divider may not be the same in some of the "A" versions.Eimac data gives the pair of triodes an output rating of watts CCS.
This particular amp produces in excess of W when driven with 50 or 55 watts, depending on band. At W out, the grid current meter just barely registers. The tubes are obviously in good shape. This amp has had the filter caps replaced, but otherwise is "factory stock" to the best of my knowledge. It looks extremely nice. No scratches or defects of any sort. All lights work as they should. Detron amp for sale. Good condition, works fine.
Tubes appear strong. Wired for v. Please text questions or replies. Amplifier cover 80, 40, 20, 15 and 10 m band with modification. The amplifier has no 10m modification at this time.
Need to be performed by technician. The amplifier was used only for very short time. Look like new inside. Outside I wou It is in good condition, but has been in storage for a long time,so it is being sold as-is. It lights up, with no smoke. It has 4 6LQ6's that light up ok too. It is rated at 1KW i Lights up with no smoke!
Copy of manual included! Can meet buyer at Report Ad. Email Poster Message.