Good information. Thank you.

Interesting discussion. The high SWR on the input side of the SB200 might be due to reduced capacitance of some of the capacitors in the filters. I like to use a return loss bridge or a Boonton Rx bridge in cases like this. A nanoVNA might work ok, but I have no experience with one.

Hi, thanks for sharing, very interesting choice of triple triode and great clear explanations, definitely high quality engineering! Would be very interested in your point of view of choosing active RIAA correction ? Thans

really like the format of this video. No fluff, all business. thank you.

I did this about 2 years ago and it works a treat. It's as though the YT100 board was made for the battery compartment on the 897! I got the idea from EC1CW who modified his some time ago and posted the video. I used two 90 deg PL 259 connectors and soldered them together to bridge the radio out and tuner in ports. I then bought a long CAT cable and cut, re soldered it to give a real tidy look to the back of the radio with no excess cables hanging off. 👍👍

What is the point of the SO239 at the bottom that doesn't connect to anything?

Well, you will know if you ever get struck by lightning because your cement will explode.

This is very smart and tempting to try

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.

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?

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

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 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.

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..

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.

What did you do to keep the water out?

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*)

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 !

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

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.

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 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.

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.

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