Swan Mark II Amp

[Robb]

Not to mention it's his first post on Fweds site.

Hope you didn't do paypal gift.

Enough negativity, I think you did okay. I'd like to powder coat and silk screen it.

It would look cool.

Yeah, I saw that too.

Nope; regular Paypal payment so they would cover it.

Hope I did OK. Thanks. A real tube amp!

ROTFL!
Powder coat?!? Silk screen!?! You will probably have silk screen images of nekkid women on this thing if you had your way. lol!

 

[Mudfoot]

Oh no, I am very good with powder coating. My sister does custom silk screening and has been a very talented artist for over 46 years. She can hand paint and detail various fonts/styles that are difficult to discern from commercial printing.

I could make that thing look original, but doubt you would invest that much. I mostly do firearms, custom car parts and just about anything else that will fit in my oven. My dream is to one day have a big oven. It's just another hobby that I can't afford.

 

[Robb]

(Pictures courtesy of mods.dk; not my amp!)

Examine each picture carefully and note the differences.

I've heard that there is a great deal of trouble finding the right schematic for these amps - because their internal parts in the RF Deck are different. You can see this from the photos of two Mark II decks. See the different inductor coils attached to the plate voltage adjustment variable?


Well, at this point will be making sure that it works correctly and is being used correctly. Sure it is going to get some cleanup and an inspection even before it is fired up. Not too concerned about they way it looks. Does it look like it is that bad to you - m42?

 

[Robb]

Soooo . . . here is a question for all y'all:

Since this amp doesn't have a tuned input I will have to use the antenna tuner in the radios. Now; how will I tune this? Will the amp have to be keyed on and the amp output going into a 50 ohm dummy load? How is this done?

 

[n8fgb]

Always tune into a dummy load. Tune with the radio first, no tuner, at full output. The radio will fold back to a safe level. after tuned up, key up and turn on tuner.
Rich

 

[Robb]

Always tune into a dummy load. Tune with the radio first, no tuner, at full output. The radio will fold back to a safe level. after tuned up, key up and turn on tuner.
Rich

Guess I didn't state the question correctly.
What I meant was tuning between the radio and the amp input and NOT the output of the amp. Shouldn't I have a dummy load connected to the amp - even though amp is 'off' - so that I can tune the load that the radio sees first between the amp and radio?

Never mind; read the manual again.

 

[Robb]

One more thing. If you look carefully at this picture of the power supply, you will notice that there isn't a voltage doubler board in the power supply unit. The second picture is what a stock PS looks like for this amp. I'm guessing here; but if this amp doesn't have a voltage doubling board in it and the last owner of this amp claims that the amp is putting out legal limit power; then the transformer that was replaced must have a greater voltage output/larger transformer so that it has enough plate voltage to drive these tubes to full power.

Doesn't make sense that it doesn't have a voltage doubler in it.

The supply I have

A stock supply with the voltage doubler board

 

[Robb]

Talked to the owner today on the phone. He said that the stock transformer was replaced with a Peter Dahl unit. That transformer is able to drive the amp to full output. One mystery solved.

I've read some comments online saying that even though the tubes are capable to do a full 1.5kw output and more, that the other internal parts of this RF deck aren't really built to support that much output. Not that I need to run it to full output anyway - I don't. However, the previous owner said it can and did run it there. Arcing of tuning caps may be an issue at that power level - for one. As beefy as these parts may appear, I really don't need to waste ~$400 for a pair of tubes due to arcing just to see it do a full output test.

I also noticed that some of the parts on the RF deck look like they have never been replaced. I suppose it wouldn't hurt to replace all of the resistors, disc and electrolytic caps, and the diodes. Cleaning the switches and variables thoroughly - and a overall cleanup in general. The power supply has already been gone through; so the RF deck will probably need the focus of attention.

Probably wouldn't hurt to put in a protection diode for the meter too. Sure there aren't too many of those meters just lying around for this old box. Curious to know just how many volts the new transformer puts out and how that meter is able to gauge it. With that extra voltage, that meter must be at/above its full scale. As an estimate, the stock supply provided 2.8kv's @1.25kw's out in SSB mode; so the Dahl transformer must be doing around 3.2kv's in SSB mode to get the 1.5kw out. Again, just an estimate based upon proportions . . .

 

[Needle Bender]

I liked my MkII. It looked factory new inside & out, especially after I took TR3 Resin Glaze to the face and buffed it out like an old enamel paint automobile. Really made it look new.

And thumbs-up on the Dahl linear supply, upgrade the isolation caps & it should do fine at full legal output.

I wonder if the different looking amp with the smaller inductor inside isn't set up for 6m since I believe they also made a 6m version?

I stupidly sold my MkII 5 years ago for $650 because of the lack of tuned input, at the time I didn't know about this & this.

With 2 of the dow key relays, when you key, the tuner is put in line until you unkey, so your receiver won't lose sensitivity from being routed through a tuner on RX.

I fried the autotuner in an Icom IC-746 by trying to use it to tune the input of an amp.

Robb, on what band & freq will you be using it?

Sorry for the crappy picture on eham, I had a crappy camera & little experience uploading pictures at the time.

 

[Robb]

I liked my MkII. It looked factory new inside & out, especially after I took TR3 Resin Glaze to the face and buffed it out like an old enamel paint automobile. Really made it look new.

And thumbs-up on the Dahl linear supply, upgrade the isolation caps & it should do fine at full legal output.

I wonder if the different looking amp with the smaller inductor inside isn't set up for 6m since I believe they also made a 6m version?

I stupidly sold my MkII 5 years ago for $650 because of the lack of tuned input, at the time I didn't know about this & this.

With 2 of the dow key relays, when you key, the tuner is put in line until you unkey, so your receiver won't lose sensitivity from being routed through a tuner on RX.

I fried the autotuner in an Icom IC-746 by trying to use it to tune the input of an amp.

Robb, on what band & freq will you be using it?

Sorry for the crappy picture on eham, I had a crappy camera & little experience uploading pictures at the time.

Do you have pictures of your Mk II?
Like to see it inside and out if you have them please.

There were two variations of the internals of the RF deck that I can find so far. I've heard there may be more too. Not for 6m; just a design variation.

This amp was purchased with the intention of using on 10-80m. I'm a huge fan of 10m BTW.

Don't understand why there was a problem between the radio's auto tuner and the amp input. Still have a whole lot to learn before I even use this amp.

 

[Needle Bender]

Do you have pictures of your Mk II?
Like to see it inside and out if you have them please.

There were two variations of the internals of the RF deck that I can find so far. I've heard there may be more too. Not for 6m; just a design variation.

This amp was purchased with the intention of using on 10-80m. I'm a huge fan of 10m BTW.

Don't understand why there was a problem between the radio's auto tuner and the amp input. Still have a whole lot to learn before I even use this amp.

I have a host of pics on my other dead Dell, number 3 dead Dell... I'll look in my email and check for some pics I might have sent to a friend years ago, but I have doubts. I can tell you this, it looked like the one with the large tank coil since that would be required for 10-80. The other one appears to have been set up or modded for monoband ops, perhaps 6m, 10m or even 11m.

The large inductor would be tapped in several points along it's coils appropriately for each band selected. I can't see how the one shown with the small coil could ever be made to resonate on low bands.

Do you have an 80m antenna?

 

[Robb]

I have a host of pics on my other dead Dell, number 3 dead Dell... I'll look in my email and check for some pics I might have sent to a friend years ago, but I have doubts. I can tell you this, it looked like the one with the large tank coil since that would be required for 10-80. The other one appears to have been set up or modded for monoband ops, perhaps 6m, 10m or even 11m.

The large inductor would be tapped in several points along it's coils appropriately for each band selected. I can't see how the one shown with the small coil could ever be made to resonate on low bands.

Do you have an 80m antenna?

Yeah; I have a fan dipole for 10-80m.

If you go back a couple pages on this thread, you will see two different pics of the innards of this amp. There are two different schematics for these RF deck too. These are design changes that Swan used from '69 on up. Sounds like you had the later version.

 

[Shockwave]

(Pictures courtesy of mods.dk; not my amp!)

Examine each picture carefully and note the differences.

I've heard that there is a great deal of trouble finding the right schematic for these amps - because their internal parts in the RF Deck are different. You can see this from the photos of two Mark II decks. See the different inductor coils attached to the plate voltage adjustment variable?


Well, at this point will be making sure that it works correctly and is being used correctly. Sure it is going to get some cleanup and an inspection even before it is fired up. Not too concerned about they way it looks. Does it look like it is that bad to you - m42?

Notice the stock one has 3-400Z tubes in it too.

 

[Needle Bender]

OK, now I'm using a better video card and I see the dual tank coils in the lower picture - they looked like capacitors on the other video card!

Yes, mine was the top version. sniff sniff :sad: If ever you see one with the vernier pointers painted red, that might be my old one.

Cool on the fan dipole, where do you like to hang out on 80m & what time are you on? I know we can easily hear each other, a friend (Jeff) in SJ typically haunts me @ 40over in voodoo on his Delta loop. :laugh: