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RCD66
США
Добавлен 4 мар 2014
This channel is my profession and my hobby. Circuit designs of past and future. Repair of old and new devices.
Yaesu FT 897 Tuner Modification
I modified my Yaesu FT 897 for an internal automatic antenna tuner. I removed the PCB from a LDG YT-100 antenna tuner and placed it into the battery compartment of the 897. It worked out really well.
Просмотров: 768
Видео
Flag Pole and End Fed Antenna Update
Просмотров 1516 месяцев назад
I have some updates to my flag pole vertical and the end fed long wire. I finally was able to get the flag pole to operate on the 10M band by building a fixed matching box which can be remotely switched in when using 10M. I also improved the end fed long wire by adding an extra long wire from the tower top to ground. Not sure how this wire is functioning to improve things so much. I welcome com...
Audio Tube Tester Design
Просмотров 1696 месяцев назад
It seems tube testers do not check for some major issues which plague audio tubes such as micro phonics and gain matching between multiple sections. Preamp tubes such as 12AX7's in a high gain environment can have many mechanical issues which standard tube testers will not test for. My tube tester design will look for these type of problems.
Phase Linear 400 Power Amplifier Refurbished
Просмотров 3,8 тыс.6 месяцев назад
I always wanted one of these back in the 1970's. Found one as is on Ebay so I thought I would give it a try at repairing it. I tried to keep it as original as possible. I did however, design a couple of PCB's to fix a couple issues.
SB200 Input Modifications (Part 2)
Просмотров 2757 месяцев назад
I made a few changes to the original modifications of my SB200. I finalized the adjustments to the input matching circuitry and ran tests all of the bands.
SB-200 Modifications to make it better.
Просмотров 6 тыс.Год назад
This video shows an attempt to make my SB-200 work with my Icom 745 transceiver.
3 Tube Guitar Amplifier Design
Просмотров 1,7 тыс.Год назад
Thought I would try a guitar amplifier design using a couple compactron tubes. One is a 6U10 triple triode and a 6DZ7 as an output tube. I also use a 6AV6 as a distortion amp. This design uses used a switch mode power supply which I will explain in another video.
Flagpole Antenna Project
Просмотров 87 тыс.Год назад
I made an experimental flagpole vertical antenna. It seems it works the best as an off center fed antenna for 20 and 15 meters. My goal is to create antennas which are resonate into 50 ohms where no tuner is needed. Many are asking about the SWR Analyser. It is an HP-8712B.
Active Antenna Design
Просмотров 1,1 тыс.Год назад
I wanted to build this Active Antenna circuit for my short wave radio receivers. The basic design is called the pa0rdt Mini Whip. Many versions can be purchased online.
Hallicrafters S-38 Restoration
Просмотров 2,7 тыс.Год назад
I wanted to restore this Hallicrafters S-38 receiver to make it fully functional. To keep the look as original as possible so I used the original wax capacitor casings an placed the new capacitors inside them.
Tour of Argon Labs 2006
Просмотров 545Год назад
We took a tour in the belly of Argon labs back in 2006. Lots of technical footage below the accelerator ring showing the massive power required.
Vacuum Tube RIAA Phono Preamp Design
Просмотров 11 тыс.2 года назад
Using two 6U10 vacuum tubes, I designed this stereo RIAA equalized phono preamp. This design uses an active feedback equalization network which turned out to work quite well. I also designed the 300v power supply for powering the 6U10's. The entire amplifier operates from a 12v, 3A wall wort.
A 300V Switching Power Supply for Vacuum Tube Preamplifiers
Просмотров 7 тыс.2 года назад
I needed a power supply for a Vacuum Tube RIAA Phono Preamplifier . I didn't want to use a standard 60hz transformer because of not only the size, but also the noise and hum it can introduce. I found an existing switching transformer which gave me a good 6 watts of power which is plenty for most tube preamplifiers.
Voice Module For Repeater Controller
Просмотров 2292 года назад
I designed a voice module to read the frequency display data of a Kenwood 7950. A previous video shows my display decoder by collecting the display data from the 7950, converting it to serial data, then displaying the readout data on the repeater controller. I was able to use this same data to create an audible playback of the present frequency selected on the 7950 which allows one to remotely,...
Remote Controlled Kenwood 7950 2 Meter Radio
Просмотров 6743 года назад
This video explains how I modified a Kenwood 7950 Transceiver for remote control. This made the 7950 function as a 2 meter cross band for the 440 repeater controller.
ID and Audio Delay Interface for Repeater
Просмотров 2273 года назад
ID and Audio Delay Interface for Repeater
My Ham Radio Repeater Design (Main Controller)
Просмотров 5763 года назад
My Ham Radio Repeater Design (Main Controller)
49-1 Balun Design and End Fed Antenna Experiment
Просмотров 28 тыс.3 года назад
49-1 Balun Design and End Fed Antenna Experiment
This is very smart and tempting to try
Whats nice is using a switching power supply keeps 60hz away from the high gain circuitry.
Excellent presentation. I rebuilt a Dynaco Stereo 400 last year, and it was a very satisfying project. Your ability to design and add PCB for upgrades is impressive.
Yea, It was a fun project.
I have used tje 6U10 compactron as a phono preamp but i did not destroy good tube phonics with an op amp. If ypu know you are driving a tube section of 250k input impedance then you have no worries to drive direct from your triode
Dont destroy ypur good tube audio by inserting an op amp. Your triodes can drive a preamp quite well. No nerd for op amp. You have destroyed all the good you have done
Wow...this amp brought back memories as I had it back in the day,
Great video! Very instructive and good ideas for improving an SB200. Tnx es 73 de kc4i.
Thanks for the clamp down boards, they are very nice. I am also glad you posted a picture of the pl14 board. I would have gotten Q1 and 2 reversed had I not taken a close look. A couple tips: Change out C6 with a 470 1W capacitor for better, deeper, bass response. Also, bridge the legs of C6 with 2 IN4148 diodes, in opposite direction to each other. This is known as the Geppeto mod, and helps prevent latchup and oscillation. Joe of White Oak Audio can explain the technical aspects of this mod. Once again, thanks for the great video.
Good Job! MM or MC?
Its currently set up for MM. I don't have a MC type to experiment with at this time. Thanks
beautiful work!
Great video. I'd be interested if you would be selling the unpopulated protection board. I'm restoring 2 PL400's, and really like your design. Thanks Richard
I'll check an see how many boards I have left.
@@CIRCUITDESIGNER thanks!
@@Sunnbobb I have 4 boards available.
@@CIRCUITDESIGNER Thanks, I sent an email.
73's🎙KD9OAM🎧
Nice and clean!~ love this idea!
Hi from Belgium ! Good job !! Did you adjust the bias on the control board ? Do you sell protection board for speakers ?? thank you.
I show bias check at 20.23 into the video. Offset was around .3 volts. I have a couple unpopulated protection boards left.
I have an old SAE I would like to have it put back online. I really miss listening to it.
Dear Sir, I would like to ask a question about your protection circuit. What is the electrical current specification for the 1.75uH inductor? Or if you made it yourself, what is the AWG, number of turns, and diameter? I would be very grateful if you allow me to use your design to add to my amplifier. Thank you very much.
It's 10 turns #14 enamel wound on 3/4 dia PVC pipe as a form.
I noticed the idea of "water tight" repeated. Ive learn designing to minimize water infiltration BUT include a path for water to exit helpful. An example, ive installed "water tight" power outlet boxes only to find water finds a way in, but no way out and corrodes the internals.
would you share the gerber file?
#00000110110 #true400RMS..
#0001110000001. #power7 09:12:01
As I used my cheap Harbor Freight Flag pole, for an antenna mast, I drill and used pins to go thru the mast, instead of fighting with Hose clamps ! No more worry of variable wind speeds vibrating mast to collapse ! Just a thought ! As everyone has their own way of doing things ! The pins I used, have metal rings on one end, making for easy disassembly ! 👍😉
Very cool seeing the different steps to create that interface.
Thanks, The readout in one of my 7950's has totally died. The radio becomes worthless without a way to create a remote readout. Kenwood used carbon based ribbon cables to the readout back in the day. Totally a bad idea.
What did you do to keep the water out?
Not too much water gets in. It's sealed pretty good. I have a small 12v self priming pump just in case.
Hello RCD66, I like your commentary as it is simple but very much understand-able! I have a question regarding W8Ji's neutralizing. W8JI called out 15T #28 wire however, your schematic calls for twisted pair 30T bifilar wound? Can you help me understand the process bifilar wound, to me, it imply 2 wires side-by-side wound Vs. twisting a pair of 30T of 28 gauge wire looping around the toroid's loop core. Also looping a bifilar wound15T Vs. 30T of 28 gauge wire is a substantial change, perhaps 30T was required? Thank You for your time! :) 73's AH6BS (blue-sky *LOL*)
The toroid core I used is very small so I needed more turns. The 2 wires don't need to be twisted, just wound together.
Change the tubes, I bet it works fine on ten. Use stock parasitic chokes. The input coils are tuneable you don't need a tuner, check your input coax length. Yes you need a keying interface. Learn more before you post nonsense. Look at those bullshit parasitic chokes. Make stock ones !
Please watch the update video and be a little less aggressive.
I like that you are using compactrons, we need to continue to utilize the remaining NOS tubes to do our bidding. I experiment myself but usually on guitar amps.
Excellent idea and well executed.
I love experimenting with tubes no one wants.
Craig, I remember repairing Marantz receivers where the speaker protection relay would arch when the and burn up. It was caused by a diode in the bias circuit that was intermittent and caused the dc to slam to the minus or plus rail. When the relay opened, it provided a short to the speaker and a good path to ground for the arch.
Thanks for all the info. I'm having some issues in the SWR input for the upper bands and this will help me figure something out
What was your method to adjust the input circuit? I have an SB 200 and it runs great on 80, 40, and 20 but 15 and 10 not so well. So what is the process to trouble shoot? KN6YKE
You need a pure 50 ohm source of a minimum of 10W and adjust the input components for a minimum SWR on the input to the amp for each band. At the same time you must peak the output of the amp for maximum into a pure 50 ohm dummy load as the output tuning of the amp reflects changes to the input. It becomes a balancing act between the output and input until you get it right.
My 80-10m efhw shows an swr less than 2 at 80m and 1.5 or less on the harmonics. and starts at 10ft up to 25ft in height. I use a homemade 56:1 unun. I have a choke on a 3ft jumper under the 56:1 unun and a 33ft counterpoise wire which am going to change to a 66ft 1/4 wave at 80m and bring down the swr even more on 80m. And not rely on the coax for the counterpoise being it is only 50ft long. I also run a choke at the shack end of the coax. I am also going to shorten the132ft element to bring several bands into the center of the bands and adjust the upper band tuning coil to keep the upper bands down in their respective bands. I could just eliminate all the extra stuff by cutting the main element in half and put a 300 to 500 pf high voltage cap in the middle and call it a day.
are these for sale by any chance?
Gracias maestro
just curious to know why you felt you had to give the LED's DC, they would work just as well with AC
Cant remember, but i seem to think that they made a 700 as well.
Yes they did, and they are a bit more popular and command more money . I have a 700b myself that I am doing all the white oak and a few other upgrades .
Fantastic! I admire your approach of attempting to maintain the original design with tasteful enhancements. When and where can we buy the pcb’s you built and incorporated!?!?!? Thanks again for sharing 👍
I may have a couple extra blank PCB's around here. You would need the ability to solder SMD parts.
I bought a used one sometime ago that was dead, I changed out the fuses because they were blown but I have not even powered it up lol.... I guess haven't really been curious about whether it works or not until now.
If the speaker fuses were blown.. don't bother testing it. You've got something shorted somewhere. I find most often it's a pre-driver failure. It won't always cook the output devices, BUT I recommend you check every transistor on the main board, and all of the outputs. The first TO-3 output transistors (RCA 410's) are drivers for the main outputs. Those usually don't go bad. If it's just the main fuse that went bad, it may have been inrush current trying to reform the old filter caps. Bring it up slowly on a variac or use a dim bulb to limit current. You'll likely need new filter caps. Easy to do and easily available.
Very nice !
Thank you for all your work testing and selecting the values to make the amp work well with newer radios. I just finished restoring a SB-200 that had been in storage for about 18 years. It works well but as you have shown the input circuits leave a lot to be desired. I have tried tuning the input slugs but they are all firmly stuck in position. Did you have to work to release you slugs? What method did you use to loosen them? I also went through your first video several times to gleam information that helped me with my amplifier. 73 Ken WA1BFS
Cool project
You should have a pot on the output of the “dirty” stage so the amount of gain fed to next stage is adjustable. Most guitar players would like to control that.
Very interesting video, I'm searching something like this from months. Is there the possibility to have the final schematic of this project? It would be a fantastic thing for an electronic lover. Thank you
What about a EFLW using 1 Mile long wire antenna.
9:1 UNUN
Can you make your PDF available that shows the mark-ups for the modifications? That would be very helpful. If not, could you show full screen views on your next post of each of the mods? Thanks in advance. Steve, WA0A
I will make a blowup of the markup in the update.
@@CIRCUITDESIGNER I just bought another SB-200 (my other one is actually a SB-201). I really like these amps and the price was such that I could not walk away. This one has the Harbaugh caps mod. Best 73'a, Steve, WA0A
Looking forward to that post about the input circuit matching CIRCUITDESIGNER! I am in the process of buying an SB-201 from a buddy and I also have a IC-745 I will be driving the amp with. Steve, WA0A
I like your Thermistor in the filament circuit. I've added a small 12V, 1A DC supply, replaced the T/R relay with one having a 12V coil and a small solid state relay to drive that relay. The internal 12V is used as pullup on the SSR internal LED so the modern radio only sources 7.5mA with its' open collector transistor. I kept the RF grid grounding with SM caps but DC grounded them with chokes. For DC bias applied +50 DC during standby, or a 10W, 10V Zener diode bias through a 3rd T/R relay to the filament transformer's center tap. This make the Q current much lower (about 40mA) so the tubes don't glow as much and stay much cooler. The RF output doesn't contain out of band emission.
Why remove the input tune network and replace with a 50 ohm 100 watt non inductive resistor
I've recently purchased an SB200 and mods are interesting. Could you give me value of "back to back" diodes you installed to protect the meter?
Hi, The diodes are 1N914.
Nice project and video, thanks! Love the triple triode. I think the opamp might not be needed. The output stage, a cathode follower, has a low (<1K ohm I'd guess) output impedance. And the voltage feedback network makes that impedance even lower. The output impedance of the tube part can be measured by applying a 10K or 2K load and measuring the voltage change before and after the output resistor. Cheers!
Hi, nice work! Have you considered using a resistor-network voltage divider+ TL431 + opto isolator to do a truly isolated HV power supply?