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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Jul Fri 27, 2012 4:02 pm 
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Joined: Nov Sat 27, 2010 6:15 pm
Posts: 5449
Mark D wrote:
YES! Finally someone has brought a vintage Heathkit Williamson amp back to life on this forum. Not to sound like I know it sounds when you read this, but I've seen everything come across here BUT Heathkits for the last eleventeen or more years.
All the amps I read about in here, and rarely add much, are interesting, (That huge Stromberg Carlson has me looking for sure) and often great amps. But I've been waiting for a "big" Heathkit to show up.

I'm curious, how was the original workmanship inside the amp? I've seen some mighty good work, and I've seen just the opposite too. Some of it can be interesting, especially when someone tries to re-engineer the amp to sound better. Or whatever reason.

Heathkit use Astron caps a lot back in the day. They were inexpensive, and they had to keep the cost down to make the product marketable.
But I really haven't had any more trouble with those Astron caps than with other brands. Over all, they've done fine. All caps can go bad, even the big name ones, by the time they're 50 years old.
Mark D.


Most of these and Eicos were kits sold to hobbiest and amateurs, so build quality was all over the place. Made a few bucks by wiring up sets for less than the difference of the kit and factory wired versions. The assembly manuals were so good it was hard to screw it up.


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Jul Mon 30, 2012 6:05 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8627
Location: Litchfield Minnesota USA
Thanks.
I know. I've built multitudes of Heathkit products over the years. That's kind of why I asked about build quality. I like to see the work people have done. Sometimes, it's just downright gorgeous. Top notch work. Other times, not so much.
I've repaired the work of others on some kit products that didn't work after being assembled.
I guess no matter how simple the manual is to follow, some folks can still get it wrong.
Heathkit's golden era of audio, to me, was when they had their plethora of Williamson based amps, which eventually morphed into their AA-40 and AA-121, which are different designs but bear similarities.
Mark D.


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Jul Mon 30, 2012 8:43 pm 
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Posts: 23950
Location: Haledon, NJ, usa
Mark D wrote:
Thanks.
I know. I've built multitudes of Heathkit products over the years. That's kind of why I asked about build quality. I like to see the work people have done. Sometimes, it's just downright gorgeous. Top notch work. Other times, not so much.
I've repaired the work of others on some kit products that didn't work after being assembled.
I guess no matter how simple the manual is to follow, some folks can still get it wrong.
Heathkit's golden era of audio, to me, was when they had their plethora of Williamson based amps, which eventually morphed into their AA-40 and AA-121, which are different designs but bear similarities.
Mark D.

You've got that right!
We had an adult beginner member of our Ham radio club who bought and built a Heathkit receiver.
He told us it didn't work and could he bring it in to the club one day for us to have a look at it.
Sure.. we said bring it in.
Well what we saw was beyond belief.
Everything was connected to the proper locations and all the wires were run to the proper terminals .. and soldered... but he did not remove any insulation from all the wires....lol
There were giant globs of solder all over the terminal encapsulating the non-stripped wires!
Duh.
I guess the instructions assumed he would know to strip the insulation off?

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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Jul Mon 30, 2012 10:35 pm 
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Location: Thornhill, Ontario, Canada
Mark D wrote:
Heathkit's golden era of audio, to me, was when they had their plethora of Williamson based amps...
Mark D.

I agree. Back in the day I couldn't afford them! Now highly collectable (still looking for a W5...) and easy to refurbish as classic Williamsons.
Cheers,
Roger

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Thornhill, Ontario
Ontario Vintage Radio Assoc. http://www.ovra.ca


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Jul Tue 31, 2012 6:36 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8627
Location: Litchfield Minnesota USA
Pbpix wrote:
Mark D wrote:
Thanks.
I know. I've built multitudes of Heathkit products over the years. That's kind of why I asked about build quality. I like to see the work people have done. Sometimes, it's just downright gorgeous. Top notch work. Other times, not so much.
I've repaired the work of others on some kit products that didn't work after being assembled.
I guess no matter how simple the manual is to follow, some folks can still get it wrong.
Heathkit's golden era of audio, to me, was when they had their plethora of Williamson based amps, which eventually morphed into their AA-40 and AA-121, which are different designs but bear similarities.
Mark D.

You've got that right!
We had an adult beginner member of our Ham radio club who bought and built a Heathkit receiver.
He told us it didn't work and could he bring it in to the club one day for us to have a look at it.
Sure.. we said bring it in.
Well what we saw was beyond belief.
Everything was connected to the proper locations and all the wires were run to the proper terminals .. and soldered... but he did not remove any insulation from all the wires....lol
There were giant globs of solder all over the terminal encapsulating the non-stripped wires!
Duh.
I guess the instructions assumed he would know to strip the insulation off?


Actually, it's worse than that! Heathkit has explicit instructions on insulation removal and soldering technique in every manual. He just didn't read the manual.
I learned proper soldering technique before I was ten years old. I guess not everyone is that lucky.
Mark D.


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Aug Sun 19, 2012 6:25 pm 
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Posts: 2528
Location: Thornhill, Ontario, Canada
engineer wrote:
engineer wrote:
... The solution is a VLF Shelf circuit in each 5881 g1 from 6SN7 driver. I had to do this on my other Williamson amplifier built from scratch. There was a long discussion on this on the[url]rec.audio.tubes[/url] news group recently. Patrick Turner in Oz is the main guru on VLF stability. I'm intrigued that there was no discussion on VLF stability, to my knowledge, in 1947 when the Williamson design first came out. However, they did specify very primary high inductance OPT's back in the day, at least 100H - this delays OPT phase lag [NO!, see below] as the frequency goes down.

Correction: it delays phase LEAD i.e. OPT's give phase lead as the frequency goes down, as do RC couplings, adding to potential VLF instability. My apologies, I must be more careful!
Cheers,
Roger

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Thornhill, Ontario
Ontario Vintage Radio Assoc. http://www.ovra.ca


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Nov Wed 13, 2019 6:21 pm 
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Joined: Mar Sun 25, 2018 10:21 pm
Posts: 9
Some comments:
1)
I have never seen a bottom cover on a W4M/AM. It seems like the fossilized rubber feet that are or were present would have precluded the compatibility of a cover and feet simultaneously.

2) I am puzzled about references to asbestos...maybe because I've never seen anything in one that made me think of asbestos, nor in the parts list...might that have been 'fishpaper'? Very common insulator, still manufactured, a.k.a. vulcanized fiber, sometimes explained as being made of cellulose, but also sometimes classified as a plastic, yet still categorized as a type of electrical insulation paper.

3) Re: potting of transformers...I think I have read statements about poorer thermal properties of potted vs. unpotted transformers, but there are benefits of potting, so hopefully the transformer designer gave some thought to that. Cost is definitely NOT one of the advantages of drawn can housed transformers!

There are more transformer failure modes than we can even count, and combined with many different manufacturers techniques and materials, and what someone else said, age (decades of use, misuse and lack of maintenance), I don't even want to form an opinion about reliability of one transformer style or company. Life is tough for transformers...

The W5 or W6 (or both?) had a much-revered Peerless output transformer...while some people dismiss the 'ordinary' Chicago grade of OPT in W4 and other Heath Williamson-inspired amps, one Peerless OPT is found bad so frequently it's something I just avoid...has cult value, but is probably a risky investment. It's expensive to rewind or replace because it was a complicated (interleaving) design...probably got the short end of the accounting stick with regard to insulation design (or not...we (I) can't determine that from my armchair).

4) I am frustrated with the inconsistent market value of the W4 variants...on eBay, sometimes a parts unit sells for as much or more than a working one, or even a refurbished one! I sometimes want to sell mine (4M & 4AM) when the market is high...other times it appears I shouldn't put another dime into them because I will never get it back, and other days they are worth more to me for a conversion project! Thinking that way today...that's how I ended up at this thread.


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Nov Wed 13, 2019 10:33 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3378
Location: Seattle WA US
Murray-
Welcome to the forums.
Did you realize you were picking up a 7-year-old discussion ?
-Chuck


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Nov Thu 14, 2019 1:20 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 20719
Location: Utica, NY 13502 (USA)
The information and comments in old threads are usually still valid which is why they are kept available.

Dave


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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Nov Thu 14, 2019 1:49 pm 
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Joined: Aug Tue 28, 2018 9:22 pm
Posts: 1325
Location: Sanford Fla 32771
My HA2 with preamp and radios, Heathkits.


Attachments:
Amp HA2.JPG
Amp HA2.JPG [ 571.93 KiB | Viewed 104 times ]
HeathKit.JPG
HeathKit.JPG [ 378.15 KiB | Viewed 104 times ]

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Paul of Florida (Click below for my collection)
https://paulsironhorse.smugmug.com/
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 Post subject: Re: Heathkit W4-AMamplifier success!
PostPosted: Nov Sun 17, 2019 2:40 am 
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Joined: Nov Fri 10, 2006 12:24 am
Posts: 2528
Location: Thornhill, Ontario, Canada
pauls.ironhorse wrote:
My HA2 with preamp and radios, Heathkits.
Paul, nice pictures! I have exactly the same units, plus a couple more WA-P2's (all refurbished.) They get mixed and matched with other gear on a whim!
Actually, it's about time I "wound up" a couple of WA-P2's for stereo, driving a couple of Wiliamson amplifiers. I have a small, stand alone P/S for these pre-amps so that I can use any power amplifier to hand.
Cheers,
Roger

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Thornhill, Ontario
Ontario Vintage Radio Assoc. http://www.ovra.ca


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