[R-390] R-390 Digest, Vol 59, Issue 33
Paul Anderson
paul at pdq.com
Mon Mar 30 10:13:58 EDT 2009
Another option is plastic media blasting. Clean plastic or walnut
will tend to leave all or some of the original finish on the harder
metals, and not erode softer metals too badly.
I use fine glass beads on aluminum that I am repainting - for panels
and knobs it works fine - I usually soak in paint stripper first to
soften the paint, especially in the engraved letters or indicator
lines on the knobs.
I don't recall having used plastic media on radio bits, but there are
certainly cases where I'd try it. In my particular case, the problem
is my plastic media is a) expensive, and b) I wound up contaminating
it with some glass beads, so the end result is not bad, but still
more etching than I'd like in soft materials.
I use a 5HP dual stage compressor, and a home made TiP cabinet made
from a TiP kit (I think they're still in business). I'm not sure if
it is the draw tube or what, but I don't get very good blasting action
with the siphon at present. I also have a pressure blaster which
works amazingly well with the dual stage compressor, but it far far
more than you'd ever use on any radio I know of.
Another approach you could take is seeing if a ammo case tumbler with
walnut shell running overnight would remove paint. I doubt it, but it
is worth a shot (snicker).
Paul
On Sun, Mar 29, 2009 at 11:50 AM, Richard Green <k7yoo at yahoo.com> wrote:
> Glass bead (fine grade) works extremely well on panels and knobs, but use caution on delicate items. I have done numerous knob sets and panels over the years--all with good results. NEVER use silica sand as it will embed in the metal. I recently did an SP 600 chassis with walnut shell and it was OK but was really more of a thorough cleaning than metal refinishing. Soda blasting would have been a better choice for the chassis. If I were setting up for production I would have both, but since I only do one a month I get by with the glass bead machine and a handheld blaster (Harbor Freight) that I use with walnut shell (McMaster Carr).
> Skip
> K7YOO
> --- On Sat, 3/28/09, r-390-request at mailman.qth.net <r-390-request at mailman.qth.net> wrote:
>
>
> From: r-390-request at mailman.qth.net <r-390-request at mailman.qth.net>
> Subject: R-390 Digest, Vol 59, Issue 33
> To: r-390 at mailman.qth.net
> Date: Saturday, March 28, 2009, 11:00 AM
>
>
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> Today's Topics:
>
> 1. Re: SERIAL 163 FOLLOW UP (David Wise)
> 2. Re: SERIAL # 163 (Pedro Del Valle)
> 3. media vs soda blaster (odyslim at comcast.net)
> 4. Re: media vs soda blaster (Chris Kepus)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 27 Mar 2009 10:09:23 -0700
> From: David Wise <David_Wise at Phoenix.com>
> Subject: Re: [R-390] SERIAL 163 FOLLOW UP
> To: "r-390 at mailman.qth.net" <r-390 at mailman.qth.net>
> Message-ID:
> <339D67D3FFE9984AADF43212D53D0ED80E29140256 at hil-exch2k7.phoenix.com>
> Content-Type: text/plain; charset="us-ascii"
>
> This should remind us all to TAG OUR MODS.
>
> Guilty,
> Dave Wise
>
> Motorola 363-PH-54 S/N 1014
> - Adjustable PTO Tempco
> - Add F103
> - Carrier Zero Redesign
> - Inrush Limiter
> - 3DW7
> - AGC Clamp
> - Moment Of Silence
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net] On Behalf Of RICHARD MC KINNEY
> Sent: Friday, March 27, 2009 9:36 AM
> To: r-390 at mailman.qth.net
> Subject: [R-390] SERIAL 163 FOLLOW UP
>
> Thanks to this forum my R390A is now working on am and cw/ssb. Yesterday I sat down and drew up a schematic of my bfo circuit and could see there is no way the 6BA6 that it came with in that socket would work. I was up against a brick wall. Then thanks to this forum I looked up the product detector mod and there was that schematic I drew up but it had a 6BE6 tube. I put in a 6BE6 and off she went working fine. I don't intend to remove the mod now but I do see a bunch of the old caps that need changed. Someone sure did a factory looking job on the mod and it REALLY had me fooled.
> I was in the Air Force in the 60's as a radio repairman. I was WN7DGD in my barracks with a homebrew Tx and a Knight R 100. On week ends I would haul an R390A up to my room and operate. What a great rig. Now I'm proud to have one and will work to get it in good shape. So thanks to all that responded and helped me thru my problem. 74 Rich
>
>
> ------------------------------
>
> Message: 2
> Date: Fri, 27 Mar 2009 21:02:53 +0100
> From: Pedro Del Valle <ea2ig.pvr at gmail.com>
> Subject: Re: [R-390] SERIAL # 163
> To: R-390 at mailman.qth.net
> Message-ID:
> <8ee5f0630903271302p6dbbd774tfdde704fab9727e2 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> I have two R-90A one EAC and the other a Capehart and a R-390 Collins. None
> had a Relay.
> But I remember of an article in an old HAM RADIO MAGAZINE With a
> modification using a 6BE6 in sustitution of the 6BA6, for a product
> detector, and a Relay to switch AM/SSB with the BFO ON/OFF swiitch.
> Excuse my poor english. Hope is of help
> Pedro EA2IG
>
> 2009/3/27 RICHARD MC KINNEY <pmcknney at bellsouth.net>
>
>> DE WB4VFN Rich
>> I have a R390a Serial @ 163. Problem is turning on the BFO looses all
>> output. Rx is ok all bands with BFO off. I have a manual for thr R390a but
>> I guess mine is an earlier model. The BFO in mine is nothing like the
>> schematic. Mine has a small relay that is switched on by the BFO switch. I
>> don't think this is any kind of mod as it looks factory wired. The BFO
>> circuit is also very different then the schematic I have. The rig was
>> given to me and I would love to see it work again properly. So far I've had
>> to change the 17 mc crystal and a few tubes to hear it work again. Anyone
>> have a schematic with a relay in the BFO switch? 73 Rich
>> ______________________________________________________________
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>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 28 Mar 2009 01:00:07 +0000 (UTC)
> From: odyslim at comcast.net
> Subject: [R-390] media vs soda blaster
> To: r390 list <r-390 at mailman.qth.net>
> Message-ID:
> <1533776958.377021238202007003.JavaMail.root at sz0106a.westchester.pa.mail.comcast.net>
>
> Content-Type: text/plain; charset=utf-8
>
> Hi Gang,
>
> I going shopping tomorrow for some paint stripping gear.
>
> Is there anyone on the list that has used media blasters
> as well as the soda blasters? My reason for asking is I have
> no experience with either. I have only used the old sand blasters.
> I want to strip paint from the front radio panels knobs and sides.
>
> Which would be better?
>
> Media blaster with walnut shells or soda blaster?
>
> Any input from experienced individuals?
>
> Your advise greatly appreciated.
>
>
> Regards, Scott W3CV
>
>
> ------------------------------
>
> Message: 4
> Date: Fri, 27 Mar 2009 20:36:43 -0700
> From: "Chris Kepus" <ckepus at comcast.net>
> Subject: Re: [R-390] media vs soda blaster
> To: <odyslim at comcast.net>, "'r390 list'" <r-390 at mailman.qth.net>
> Message-ID: <5670BF2BD45C464E888C13CE50750FFA at compmom>
> Content-Type: text/plain; charset="us-ascii"
>
> Scott,
>
> Soda blasters are great because soda does not damage the metal as it strips
> the paint, nor does it damage rubber or plastic moldings. However, soda
> blasting does not remove rust.
>
> Abrasive blast systems using aluminum oxide, glass bead, etc., are great
> because they can give you a paint ready finish fairly quickly and various
> media grades are available (less or more aggressive) depending on your
> project.
>
> You need to hit Google and read up on the subject. One easy read that may
> help you is "Abrasive Blasting vs. Soda Blasting For Paint Stripping" at
> this site:
>
> http://www.eastwoodco.com/jump.jsp?itemID=1493&itemType=CATEGORY&path=1%2C3%
> 2C688%2C1319&KickerID=490&KICKER
>
> 73 and have a blast!
> Chris
> W7JPG
>
> "Good Strippers have more fun!"
>
>
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
> ------------------------------
>
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>
> End of R-390 Digest, Vol 59, Issue 33
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