Recovered PT from Sommerkamp FT277 wich is B+ Current ? How Can use it ?

[kagliostro]

I recovered a nice Power Transformer from a dismissed Sommerkamp FT277 that was missing of some parts

Schematics here (caution large file)
http://www.radiomanual.eu/schemi/Sommerkamp_FT277_user_IZ1KGY.pdf

only PS schematic



Yaesu FT101 is the same apparatus

FT-101 Specifications

Frequency Range:  3.5-30 MHz*   (80/40/20/15/10 meters)
                          27.0-27.5 MHz (11/AUX)
                          10.0-10.5 MHz (WWV receive only)
                          * 160 meters included with B/E/F Series
Modes:                 USB, LSB, CW, AM
Power Input:         SSB 260 watts PEP DC Input (130 watts output)
                          CW 180 watts PEP DC Input  ( 90 watts output)
                          AM 80 watts PEP DC Input   ( 40 watts output)
TX Freq Response: 300 Hz - 2700 Hz
RX Freq Response: 300 Hz - 2400 Hz Standard Yaesu SSB Filter
                          500 Hz           Optional Yaesu CW Filter
Optional Filters:     300 Hz - 1800 Hz SSB Narrow(Fox Tango Filter)
                          250 Hz           CW Narrow (Fox Tango Filter)
Audio Output:       3 watts
AC Power:            Rx 35 watts, Tx 300 watts
DC Power:            Rx 0.5 amps, Tx 20.0 amps
Weight:               35 lbs
Size:                   13-1/2" x 6" x 11-1/2"

SSB = 260W PEP (input - 130W Radio Frequency output)
CW  = 180W PEP (input - 90W RF output)
AM  = 80W   PEP (input - 40W RF output)

the tubes on this apparatus are 3 one 12BY7-A (that I recovered) and two 6JS6C (not present)

the filament consumption is:

12BY7-A (at 12.6v) = 0.3A

6JS6C (they were connected in series to the 12v winding = 4.5A 2.25A)

so I think at last there are available 4.8A 2,55A @ 12.6v

about the High Voltage the question is more complicated to me

in the schematic there is a 240v-0-240v secondary winding

and the B+ is labeled to be 600v

as in SSB the input power is 260W can I assume I've 0.433A DC current disposable ?

The Power Supply is drawn in a way that is confusing me, can you give me indication about the right current disposable connected as 240v-0-240v with CT grounded (336v DC) ?

I think that 240v+240v = 480v * 1.4 = 672v is a bit too High

What can I do with this transformer ?

Many Thanks

Kagliostro

[PRR]

> 6JS6C (they were connected in series to the 12v winding = 4.5A

No, two 2.25 Amp heaters _in_series_ is still 2.25 Amps.

The HV is a FWB.

> 672v is a bit too High

Shows 600V on the plan. Also a 300V tap.

Too high for what? 6550 or KT88 will work fine at 600V Plate 300V G2 5K-6K plate-to-plate load and about 100 Watts out.

You could use a 2-diode rectifier to get just the 300V. Since it's good for about 100 Watts audio output, and typical 300V rigs make 10W-18W per pair, you want 5 or 10 pairs and loads around 1KCT. You will surely need an external heater transformer for this flock.

[kagliostro]

Hi PRR

> 6JS6C (they were connected in series to the 12v winding = 4.5A

No, two 2.25 Amp heaters _in_series_ is still 2.25 Amps.

I think there is something that is going to deteriorate on my brain, I do the same error few days ago  
(I edited the first post to correct it)

The HV is a FWB

if I google FWB I obtain FWB = Friend Whith Benefits but this didn't help me to understand (   ) please what do you mean with that ?

Looking more closely to the PS I noticed the resistor connected between the minus of the bridge to ground (R1 5.6ohm 2W) so this lower the B+ respect to the supposed 672v (480v * 1.4) is this correct ?

6550 or KT88 filament consumption is 1.6A, so two in series, connected to the 12.6v winding will leave me with 0.95A for the preamp tubes (right ?)

You could use a 2-diode rectifier to get just the 300V. Since it's good for about 100 Watts audio output, and typical 300V rigs make 10W-18W per pair, you want 5 or 10 pairs and loads around 1KCT. You will surely need an external heater transformer for this flock.

6550 or KT88 will work fine at 600V Plate 300V G2 5K-6K plate-to-plate load and about 100 Watts out.

So the best solution is a PS as in the Sommerkamp with a bridge for B+ and the CT used for the 300v B(2)+ to be used for g2 - a pair of 6550 with a 5k or 6K OT for a 100W amp

Have I understand correctly ?

Thanks again

Kagliostro

p.s.: Nothing about to understand which is the B+ current rating of this transformer starting from the voltage and the RF power ?

[sluckey]

if I google FWB I obtain FWB = Friend Whith Benefits

Friends with benefits is a younger generation term that means "OK, I'm your friend, let's have sex, no love, no commitments." In our electronics world, FWB = Full Wave Bridge.

I understand the idea of "Wow! this is some nice iron. Let's build a guitar amp." But that's a very narrow view. Sometimes it just ain't worth it to cram any ole big transformer into a guitar amp! I recently suffered similar pains. I threw away a wheel barrow full of perfectly good PTs. The 3-phase stuff was a no brainer. Just dump it. But there was a lot of single phase stuff too. Some weighed 5 pounds, some weighed 25 pounds. They were designed for my old tube radar system. I handled every one and wondered how to turn it into a guitar amp. But sometimes it's just not practical. In the end, I kept several 6.3VAC@10A filament transformers and put all the oddballs in the dumpster. Sometimes a reality check can be a sad thing. 

[drgonzonm]

i I threw away a wheel barrow full of perfectly good PTs. The 3-phase stuff was a no brainer. Just dump it. But there was a lot of single phase stuff too. Some weighed 5 pounds, some weighed 25 pounds. They were designed for my old tube radar system. I handled every one and wondered how to turn it into a guitar amp. But sometimes it's just not practical. In the end, I kept several 6.3VAC@10A filament transformers and put all the oddballs in the dumpster. Sometimes a reality check can be a sad thing. 

Now I know you will not be building any amps for Disaster Area (See Doug Adams Hitchhiker Guide to Universe for Band Reference). 
I can imagine a 10Kw amp using one those 3 phase P/Ts. I'll bet you threw those water cooled tubes out too.   

With Copper at $3.5 /lb, some dumpster diver hit paydirt. 

[sluckey]

With Copper at $3.5 /lb, some dumpster diver hit paydirt.

Oh no. Copper went a different direction. 

[kagliostro]

put all the oddballs in the dumpster

That is really very sad

Maybe someone here would have used copper and laminations for some new transformers

But it would be a big commitment in terms of time

so we must not cry too much over spilled milk

However I don't think that the transformer isn't usable

as PRR told it will be fine for a ~100W amp

and with that PS arrangement (300v High Voltage from CT and ~650v B+) I think it will be fine for some tubes I've in my stock (Edit: EL509 and GU50 - the filament of EL509 require 2A, too much for the transformer)

Kagliostro

[PRR]

> FWB = Friend With Benefits but this didn't help me

I didn't even think of that. I think I may be too old for that kind of FWB.

also:
FWB Fort Walton Beach (Florida)
FWB Friends with Benefits
FWB Free Will Baptist
FWB Frankfurter Wertpapierbörse (Frankfurt Stock Exchange)
FWB Full Weight Bearing
FWB Fixed Wireless Broadband
FWB fresh whole blood
FWB Fleetwood Brougham (Cadillac model)
FWB Fairway Buoy (marine)
FWB The Fort Wayne Ballet (Fort Wayne, Indiana)
FWB Fort Worth Belt Railway Company
FWB Freight Waybill (parcel transport declaration)
FWB Fetal Well-Being
FWB Fort Wayne Belt Railway Company
FWB Fun Wear Brands (Estes Park, Colorado, USA)
FWB Department of Fishery and Wildlife Biology (Colorado State University)

I've posted an addition to that site.


> understand which is the B+ current rating of this transformer starting from the voltage and the RF power?

RF power specifications often confuse me.

It may not help that the way amateur-radio power is measured is indirect.

In 12V DC power mode the input power is 200W. I would guess 150W-180W of this is for the final plates circuit.

6550 datasheet page 3 top-right shows a 600V condition:
http://www.mif.pg.gda.pl/homepages/frank/sheets/135/6/6550A.pdf
 
KT88 and 8417 will work in the same condition with appropriate bias change.

Note also that a pair of big audio bottles offers a little more dissipation than the pair of TV sweep-tubes used in the transmitter. This seems right because a class-B/C radio transmitter tends to be a little more efficient than a class-A/B audio amplifier, so a little more of the supply power stays in the tubes.

Note that a radio ham should not be transmitting ALL the time, should listen as much as talk. It is possible that long loud non-stop sets would overheat this transformer.

> EL509 require 2A, too much

Not too much. Less than the original power tubes. You can run two small tubes. Perhaps a 12AX7 preamp and a pentode-triode driver.

[kagliostro]

@ PRR

I didn't even think of that. I think I may be too old for that kind of FWB.

As you know english isn't my language, so forgive me if I referred to something that may seem disrespectful, it was not my intention

> EL509 require 2A, too much

Not too much. Less than the original power tubes.

I do it one other time !  

As you told me if the tube filaments are in series the current consumption didn't increase

Some time ago you give this councils:

Go by weight. If a "50W PT" is 10 pounds it is plenty hefty. Fender "50W PT" seem to be 7.7 pounds; Marshall "50W PT" seems to be 5 pound

Go for "sag". A small, 30W, PT may sag 20%. Over 100W, 5% sag may be the safe limit. So if you have a BIG hunk of iron, 300V no load, load it until it drops to 285V. Leave it in a safe place and let it cook 20 minutes, an hour, all day. Does it seem "too hot"?

so as a confirm about B+ current I can do that


Thanks

Kagliostro

[PRR]

> english isn't my language

It's "my" language, but I learned it back in the last century. This meaning of "FWB" is very new.

> seem disrespectful

Not at all. It is slightly funny, the way English changes so fast. Sometimes it gets ahead of us.

[kagliostro]

> seem disrespectful

Not at all. It is slightly funny, the way English changes so fast. Sometimes it gets ahead of us.

OK PRR thanks, this calms me, I never meant to be disrespectful

Kagliostro