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THE AM BULLETIN BOARD => QSO => Topic started by: ashart on January 15, 2010, 04:51:36 PM



Title: BigRig Status
Post by: ashart on January 15, 2010, 04:51:36 PM
Attention those following the BigRig project -

The final amplifier has been finished.  Now, only inter-deck cabling and a little bias supply is between it and being on the AM frequencies!

See it at www.w8vr.org (http://www.w8vr.org)

73 de al h


Title: Re: BigRig Status
Post by: W1RKW on January 15, 2010, 05:11:52 PM
SWEET!  Nice work Al!


Title: Re: BigRig Status
Post by: w1vtp on January 15, 2010, 06:22:26 PM
SWEET!  Nice work Al!

Yup Nice.  Gotta learn how to do that Crinkle finish


Title: Re: BigRig Status
Post by: N2DTS on January 15, 2010, 06:49:44 PM
Looks a bit better after.....

I think I would have scrapped the thing and used the parts, and you have it looking better than new!
A lot of work no doubt.

Brett


Title: Re: BigRig Status
Post by: Opcom on January 15, 2010, 07:50:19 PM
Fine job! I have to admit I do not have the patience or time to rework something to that as-new standard!

I especially like the treatment of the clipper to include the output filter. This is almost exactly as was done on an old CAA (pre FAA) limiting amp that sold for $k on evilbay. The sort of circuit allows one to clip so hard the voice looks like a square wave, yet have very little harmonics above the voice range post-filter. It allows the OM to set the clipping level for max inteligibility and not worry about harmonics.


Title: Re: BigRig Status
Post by: k4kyv on January 15, 2010, 10:12:07 PM
Nice restoration job, especially the black wrinkle paint. Was that a new wrinkle job, or simply black lacquer on top of the original wrinkle finish?  I have not been able to reproduce that kind of wrinkle finish with new paint available since the early 70's, and have wondered if anyone knows how the particular texture was done in the 30's, or if that is a totally lost art.

However, I wouldn't call it a "big rig", though. I would classify it as mid-size.


Title: Re: BigRig Status
Post by: N3DRB The Derb on January 15, 2010, 10:24:18 PM
thats powder coat. some of the powder-makers have the wrinkle finish down to a art form. It's expensive but it will outlast you.


Title: Re: BigRig Status
Post by: N2DTS on January 15, 2010, 11:38:02 PM
I did some rattle can wrinkle finish years ago that came out very well, but you have to put it on right, and bake it at just the right temp. Then you can get a small, tight wrinkle.

Room temp drying gives big wrinkles most times I think.

I don't like it, its hard to label, it gets dirty and is hard to clean.

Brett




















Title: Re: BigRig Status
Post by: N2DTS on January 15, 2010, 11:40:44 PM
Also, don't you wish the old ham gear was built like that?
I don't recall any ham radio stuff built that well...
I wish I built stuff that well...

Brett


Title: Re: BigRig Status
Post by: k4kyv on January 16, 2010, 12:27:13 PM
I did some rattle can wrinkle finish years ago that came out very well, but you have to put it on right, and bake it at just the right temp. Then you can get a small, tight wrinkle.

Room temp drying gives big wrinkles most times I think.

I don't like it, its hard to label, it gets dirty and is hard to clean.

For restoring pre-WW2 items the big wrinkles make a more authentic finish, more like the original.  Nearly all equipment of that era that I have seen had coarse wrinkled finish, and small tight wrinkles stand out like a sore thumb,  yelling "re-paint job".

The problem I have had with room temperature drying is that inevitably, there are spots that don't wrinkle at all.  Perhaps there is a critical temperature for obtaining coarse wrinkles while still achieving 100% wrinkling of the painted surface.

If it was possible to produce that particular style of finish in 1935, it doesn't seem that it should require rocket science to do it to-day.  I suspect it is more like a lost art.  There should still be someone around who remembers how it was done, and what ingredients were used to formulate the paint, but so far such a person has been evasive.  Like WW2 vets, they probably won't be with us for too much longer.

Older equipment with coarse wrinkles was usually labelled using little metal tags, not silk-screening or transfer lettering.  I have successfully cleaned old coarse wrinkles by employing a mild detergent solution with water, and  scouring with a soft toothbrush, scrubbing with a circular motion.


Title: Re: BigRig Status
Post by: W9GT on January 16, 2010, 03:48:16 PM
Magnificent work and attention to detail!  Really a beautiful restoration, while a few modern components have replaced early vintage trouble makers like old carbon resistors, etc.  I wish I had the time, skill and patience to do such a nice job on a couple of vintage rig restorations that I have to work on.

73,  Jack, W9GT


Title: Re: BigRig Status
Post by: flintstone mop on January 16, 2010, 07:55:17 PM
You are also pretty handy with web design. Nice web site......and the TX pics, of course, gud black wrinkles. DERB is probably drooling on his monitor.

Fred


Title: Re: BigRig Status
Post by: ashart on January 16, 2010, 08:36:39 PM
Thanks to all for your kind comments about the BigRig project!

Now, though, I've got to address k4kyv's objection to my calling it "BigRig".

My feelings are hurt!  :) :)

Don, "BigRig" is a name, not a description - hence the one-word spelling.

The name originated, as I explained on my website, from the rig being big relative to other gear in my OM's shack, not that it was big relative to all the other transmitters of the world.

Yes, you're right, Don - BigRig would make a decent exciter for the Henry 8K that I once owned.

Also, Don, I've gabbed a bit about the black wrinkle issues on the website at www.w8vr.org (http://www.w8vr.org)

73 de al h


Title: Re: BigRig Status
Post by: N2DTS on January 16, 2010, 09:19:30 PM
I think most people have a big rig, I have one.
Its the biggest most powerful rig in the shack.
The big rig can be a DX100 if the other rig is a ranger, or a G76....

I think it just takes practice to do a good rattle can wrinkle finish, heavy on the paint and warm dry  (not hot).

Brett


Title: Re: BigRig Status
Post by: N3DRB The Derb on January 17, 2010, 07:13:19 PM
yeah black wrinkle is a "nameplate" finish. get yer brass nameplates on there that say what you want them to say. I make sure I cop any I see at any fester.

there are 2 camps in AM - the 50's look crowd, and the 30's look crowd. I am decidedly in the 30's look crowd.
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands