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THE AM BULLETIN BOARD => Technical Forum => Topic started by: k6hsg on April 01, 2012, 01:40:18 PM



Title: Collins 75A3 capacitor kit.
Post by: k6hsg on April 01, 2012, 01:40:18 PM
I recently purchased an early serial number 75A3 receiver and was wondering if there was a source for the electrolytic capacitors?  I know that there is a kit for the 75s models.
It looks to be original with all the original parts.

I also need the BR-1 frequency standard and an 800 cycle filter.

The capacitors other than the electrostatics's look like mica.
Are they prone to fail with age.

John in Tucson


Title: Re: Collins 75A3 capacitor kit.
Post by: W4AAB on April 01, 2012, 01:45:16 PM
Not sure if he has a kit, but check with Tom N0JMY at Hayseed Hamfest in Iowa.


Title: Re: Collins 75A3 capacitor kit.
Post by: W4NEQ on April 01, 2012, 02:15:08 PM
I just did this with my 75A3:

http://www.ebay.com/itm/Collins-75A-2-NEW-Capacitor-Replacement-Kit-/360398989909?pt=LH_DefaultDomain_0&hash=item53e9742a55

KE9PQ has them - basically all the .1 uf bypasses, the PS filter, and a couple of electrolytics on the rear of the chassis.

This brought it to life,  now to fix the 2 khz / 100 khz error on my PTO ...

Chris



Title: Re: Collins 75A3 capacitor kit.
Post by: KM1H on April 01, 2012, 03:29:40 PM
Minus the can there are under $10 in parts in that kit buying name brands from Mouser. I refuse to deal with garage and basement vendors selling no name Chinese crap. That can likely has a few stuffed in there.

Hayseed quality is excellent for the can if he can make one up reasonably.

Carl


Title: Re: Collins 75A3 capacitor kit.
Post by: K5UJ on April 01, 2012, 05:05:50 PM
Awww, he even gave woo a widdle cable tie so woo don't have to find one.   ;)

Seriously, I'm with Carl--Notice he never tells you where the caps were made; who the manufacturer is, unless I missed it.
The blue lytics seem artfully rotated so identification is facing away from the camera.   You really have to be more careful about buying stuff on eBay. 

I've never really understood the thing with cap kits anyway--and I'll bet none of these kits are high quality--from any of these guys.   I can't remember where I picked this up, either here or one of the reflectors: 
http://en.wikipedia.org/wiki/Capacitor_plague

I don't think I have told this story here publicly (apologies if I have):  I took a day off last August to attend an Antique Radio swap meet in a nearby suburb.  I had never been to one of these and figured I'd go and see what it is like.  No admission fee; free parking were two incentives.  I thought there might be enough overlap between vintage bc receivers and ham radio that I might find something useful, and you never find out by staying home so off I went.

There was a fairly big flea market outside, mostly folks with console and table top bc receivers but not a few hams there selling things; I picked up a good 1970 Eimac 3-500Z so it wasn't a waste of time.   One guy had a business with a booth selling little prepackaged capacitor kits, various common electrolytic values for vacuum tube level voltages in zip lock baggies.  I asked mildly whether or not they were Chinese capacitors.  He immediately blew up and started yelling at me:  YES of COURSE they're CHINESE CAPS!!  WHAT do you EXPECT?  There's absolutely NOTHING WRONG with them!   
This went on for a minute or two with him fulminating over the difficulties of buying CDE and Illinois Capacitor and selling them.   I threw his flyer away and moved on.  Stick with US and JA caps.


Title: Re: Collins 75A3 capacitor kit.
Post by: W4NEQ on April 01, 2012, 08:50:10 PM
I kinda thought he was looking for a kit.


Title: Re: Collins 75A3 capacitor kit.
Post by: KM1H on April 01, 2012, 09:02:59 PM
I should go into that biz, I buy caps at a 100 or more a pop since I go thru a large number of overhauls on a steady basis.



Title: Re: Collins 75A3 capacitor kit.
Post by: W2VW on April 02, 2012, 11:42:38 AM
I should go into that biz, I buy caps at a 100 or more a pop since I go thru a large number of overhauls on a steady basis.



Too much personal interaction. Of course it would be fun to watch 8)


Title: Re: Collins 75A3 capacitor kit.
Post by: W7TFO on April 02, 2012, 11:58:41 AM
The whole premise of electrolytics sucks anyway.

Most of the tube gear I have doesn't need anything over 20uf.

I've gone to using high-end non-polarized caps from Solen.

Cost a couple $ more, so what?

Stick them in any way you like, won't fail later.

Here is how I do Hamarlund HQ-120/129 chassis:

73DG


Title: Re: Collins 75A3 capacitor kit.
Post by: KM1H on April 02, 2012, 06:21:46 PM
Quote
Too much personal interaction. Of course it would be fun to watch


Maybe for someone with a poor personality or other skills :o

However I put myself thru college late in life by running a mail order ham/hobbiest biz for the duration and a bit after. I loved it and might have even continued full time but having a family and no medical coverage sucks.

It was hard to break away from being able to hit the 160 to 40 grayline DX every day :'(


Title: Re: Collins 75A3 capacitor kit.
Post by: k6hsg on April 02, 2012, 07:07:33 PM
Thanks for the input guy's.
Hayseed didn't list any thing for the 75A3 so I emailed him.
He had the can which is what I really wanted and shipped it today.
I am making a list and will check with mouser for the others.
73, John
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands