Surplus store score! Collins 26c and 2x Gilfillan Bros/Bendix filters pics

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plumsolly

Well-known member
Joined
Nov 3, 2007
Messages
969
Location
Denver, Colorado
Found these today. I will post better pictures soon. The guy was super nice; he gave me a certificate for one share of Collins Radio Company stock with my purchase! The certificate should probably end up with emrr, especially considering how much help I will likely ask for while restoring these! I am looking for any information in the mean time. The Gilfillan bros/Bendix pieces have huge Bendex plugin bandpass filters. Is it ok to power the Collins up on a variac? I am really excited to turn these on. Best, Ben






 
The Collins won't do anything unless you also got the external power transformer, which no one seems to have.  Repeat, there is no power transformer on board.  Jumper the rectifier contacts, and feed it external DC and filament.  You don't want to turn on the Collins without replacing the coupling caps, as you may take out an irreplaceable transformer.  The square coupling caps can be removed, gutted, and restuffed.  Or figure out where to put new ones, disconnect the old cap wires, and shrinkwrap the ends for future museum curators to appreciate.  The oil filter caps are likely fine. 

You can buy the legit manual here:

http://www.broadcastdocuments.com/BROADCAST_DOCUMENTS/Collins.html

 
Thanks Doug - I went ahead and ordered that manual. As far as power, I will check back with the shop about the transformer. If he doesn't have it, do you recommend building an external power supply over trying to find a power transformer with the same specs to substitute? Best, Ben
 
I may be able to suggest a power transformer spec.  I am feeding DC to the unit from a General Radio PSU.  I'm guessing you didn't get the rear dust cover either; worth asking about also.  
 
I have a note which suggests the first version unit I had like yours required about 280VDC at the rectifier output position to get the meter up to the zero point.  I wrote next to it that a 325-0-325 100 mA power transformer might be the ticket, but I can't tell you why I thought that at the time. 

Be very very careful with that meter, if it's still good.  Be sure to leave it in GR or off, and never let it be slammed in VI mode.  It is of a very very rare lower level standard than is usually found among VI meters.  If the markings are still legible you will see that it's nearly turned off at only 3 or 5 dB of GR, also, and is thus only good as an indication of action rather than a valid metering device.  The version I still have is a 26C-2, using a VU meter, which hadn't been invented at the time of the 26C-1.  That meter isn't any more useful than the first, and there's no real point to improving either type. 
 
Good lord!!  I have a feeling you paid dirt for those.  Please lie to me and
tell me different! :)

I have a Collins 26c being restored at the moment.  Your Collins is sooooo clean.
Mine looked like it had been buried in the dirt.  Thank goodness the transformers
were still good.

I wish I had seen your post sooner as I have a .pdf manual I could of sent you for free.

I can get you in touch with my tech who's completely rehauling mine.  He's actually waiting
on the back ordered now shipped missing power tranny mentioned in the previous posts.

From what I've heard, these are as rare as hen's teeth.  Seeing another one got me all excited
and stuff. 

Not sure if you've dealt with Leeds out in Brooklyn, but the owner's got all the tubes you need and
is a hell of a guy.  Really cool amigo.

Congrats on your seriously f'n awesome find.  A Collins 26c looking all pretty!!!!!!!!
 
Thanks Doug - I'll keep posted as I get the manual and talk to the fellow at the shop.
cletus monroe said:
Good lord!!  I have a feeling you paid dirt for those.  Please lie to me and
tell me different! :)
:) Not quite dirt, but it was quite a deal.
cletus monroe said:
I wish I had seen your post sooner as I have a .pdf manual I could of sent you for free.
That would actually be fantastic even still. Mine wont be here for a couple of days and I am dying to see it! If you have a chance, my email is plumsolly(at)gmail Thanks.
cletus monroe said:
I can get you in touch with my tech who's completely rehauling mine.  He's actually waiting
on the back ordered now shipped missing power tranny mentioned in the previous posts.
An original or a new one? I would be very curious about the specs either way. I am leaning towards using an external transformer and the internal rectification and filtering.
cletus monroe said:
From what I've heard, these are as rare as hen's teeth.  Seeing another one got me all excited
and stuff.
I am pretty excited myself. Believe it or not this is my first real outboard compressor!
cletus monroe said:
Not sure if you've dealt with Leeds out in Brooklyn, but the owner's got all the tubes you need and
is a hell of a guy.
I have - I ordered some Dakaware knobs from him.
cletus monroe said:
Congrats on your seriously f'n awesome find.  A Collins 26c looking all pretty!!!!!!!!
Thanks!
 
http://www.el-dim.com/

He may have some of the goodies your after. I was in there once and he had a 8' tall rack of Collins Radio gear that looked like new in his showroom. It's probably there because he wants a almost new price for it  :'( but sometimes you show your interested but not at his price... I always say to him... you want cash today are do you want to wait another 30 years to sell it.

Kaz
 
Thanks Kazper - I imagine it will be easier/cheaper to find a suitable replacement that wasn't the original Collins, but having the original would be nice. I was able to find a pdf of the manual online after a bit of sleuthing. www.w5cz.com/Collins_26C_SpeechInputEq.pdf It has the transformer specs, more or less: 110v primaries, 261-ct-261-7.1-ct-0 secondaries, or something around there. Shouldn't be too hard to find something that will work. I was wondering about the the filter caps: they are in sealed cylindrical metal canisters with wire leads and no indications of polarity. I think that they are paper - it doesn't specify in the 26c manual but the 26w manual lists the filter caps as paper. If they are paper, should they still be changed? (I stupidly cut the leads off of one of them right where they met the can, thinking they were electrolytics and I was going to have to replace them anyway)
-Best, Ben
 
AAAHHH!!!!

You cut a lead on a non-electrolytic oil filter cap.  You shouldn't cut any leads on this thing; de-solder the wire at it's terminal, and shrink-wrap iso it in place as a loose end.  AFTER YOU ARE SURE YOU SHOULD EVEN DO IT!  Those things almost never go bad.  Ask questions first!  These are way too rare to fuck around with. 

I've owned two versions, and reverse-engineered the schematic and layout long before any manuals surfaced.  I doubt anyone knows these things better than I.  I've already seen the first unit I restored get trashed by the douche-bag buyer, once I unloaded it.  So they get even rarer....

I've seen maybe 6-8 units surface in over a decade of watching for them. 

 
Doug:

I've actually been to your very cool studio's website many times specifically
because I purchased the 26c and they're ain't much on the internet about it.

Mine should hopefully be in action soon. 

I would love to hear your overall opinion of the unit if you've got a moment. 
I have a 26w that adds a 3-D quality to damn near anything and I'm hoping
the 26c is the same.
 
If you search my posts here, you'll find a response chart I shot.   I haven't used the 26W, but I imagine the compression action is very similar.   You can't really make it pump, no matter how short you make the attack time.  It is very artifact free, compared to most limiter of the era, and many today.  OTOH, it's a color monster, due to the basic amp circuit and era.  The 26W should be a much cleaner sounding circuit.  
 
emrr said:
AAAHHH!!!!

You cut a lead on a non-electrolytic oil filter cap.  You shouldn't cut any leads on this thing; de-solder the wire at it's terminal, and shrink-wrap iso it in place as a loose end.  AFTER YOU ARE SURE YOU SHOULD EVEN DO IT!  Those things almost never go bad.  Ask questions first!  These are way too rare to fuck around with. 

I've owned two versions, and reverse-engineered the schematic and layout long before any manuals surfaced.  I doubt anyone knows these things better than I.  I've already seen the first unit I restored get trashed by the douche-bag buyer, once I unloaded it.  So they get even rarer....

I've seen maybe 6-8 units surface in over a decade of watching for them. 
Ok - I wont do anything else to it without asking. Here are some higher resolution pictures, as well as some pics of the cut filter cap - not sure what I'm going to have to do to get at those leads. Let me know if you have any ideas. It looks like someone had already replaced C1,3,4, and 5 with electrolytics. Maybe I'll try to find PIO caps for those eventually, too. Best, Ben









 
In the 26c-2 manual it lists the specs of the Power tx. It says it can supply 7A of filament voltage. I am looking at some Hammond transformers that seem good, but wont supply that much current. Do I need 7A or was their transformer just overbuilt? Thanks, Ben
 
Search the tube names here and it will give you how much each eat.
http://www.nj7p.org/Tube4.php?tube=6C8g
 
I'm sure you know more than me though. I don't know how much headroom one needs(if any?). 7A did sound like an awful lot though. :)
 
After looking at mouser and the Hammond catalog for a bit it seems like the 270DAX ( http://mouser.com/ProductDetail/Hammond/270DAZ/?qs=9QYNoYI37pnyT2M2vvX2UQ%3d%3d) comes pretty close. Its got 3.5A @ 6.3V and center taps for both the filament and high-voltage windings. The original PT was flexible with its taps to cover different circumstances; see here: The 270DAX has 260-0-260 high-voltage secondaries, which is pretty close, but that winding is only rated at 104mA and the original PT could provide 132mA...
Best, Ben
 
The 4 caps that have been replaced with Atoms always were electrolytics.   Looks like that 4-6 mfd oil can is done, unless you can figure it out.   The filament rating is to cover all the preamps you might daisy chain off of the unit.  I think that manual is a different scan, so now there are two.  As usual, all I have to do is reverse everything to make the real info show up!

plumsolly said:
I was able to find a pdf of the manual online after a bit of sleuthing. www.w5cz.com/Collins_26C_SpeechInputEq.pdf

Amazing; a great manual scan with the fold out schematic still folded up!.  


The 270DAX has 260-0-260 high-voltage secondaries, which is pretty close, but that winding is only rated at 104mA and the original PT could provide 132mA...

Add up the current from the manual....41 mA.   I'm running mine on a 70mA General Radio PSU.  


'Bypass' is reverse polarity from 'limit' position.  True on both units I've had. 

You will want to use the bridging input, and you will find the level controls still touchy, and not ideal for modern usage. 

 
emrr said:
The 4 caps that have been replaced with Atoms always were electrolytics.
Oh, ok. Are the the other rectangular can caps (c2, 6, and 7) electrolytics as well?
emrr said:
Looks like that 4-6 mfd oil can is done, unless you can figure it out. 
I think I can solder some leads back onto it - it will look bad and every time I see it I will be reminded of the mistake. But, so it goes...
emrr said:
The filament rating is to cover all the preamps you might daisy chain off of the unit.
Cool. That makes sense.
emrr said:
I think that manual is a different scan, so now there are two.
The one I got from cletus monroe is for the 26c-2 and the one I linked to is for the 26c-1, I think. Did you see it says 'Price Ten Dollars' on the first page?!
emrr said:
Add up the current from the manual....41 mA. 
Oh, awesome!
emrr said:
'Bypass' is reverse polarity from 'limit' position. True on both units I've had. 
Interesting. I think what I will do once I get it up and running is put adjustable attack and release controls on separate 1ru panel with the power switch, fuses, xlr/trs connectors, and hard bypass.

Thanks for all your help so far, Doug. Let me know if you would like to have that Collins stock certificate for your collection, I'll post it to you.
 

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