20100523.ba v04_n334.bam.20100523 >From ???@??? Sun May 23 17:22:24 2010 -0500 Date: Sun, 23 May 2010 17:22:18 CST From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4334 Message-Id: <20100523232218.B47849DED25@minime.theporch.com> BOATANCHORS Digest 4334 Topics covered in this issue include: 1) What Receivers? by 2) RE: What Receivers? by "Singley, Rodger" 3) Re: What Receivers? by Chuck McGregor 4) Re: What Receivers? -Correction by Chuck McGregor 5) Heathkit sb221 schematic print by ray jefferson 6) Re: What Receivers? by "Sandy" 7) R-390A progress... by Ben Hall 8) Re: R-390A progress... by Jack Harper 9) Re: R-390A progress... by john 10) Re: R-390A progress... by Scott Robinson 11) Re: R-390A progress...and 450V cap availability by Scott Robinson 12) Re: R-390A progress... by Ben Hall 13) Reminder: KSM on Tomorrow With Multiple Ships by Richard Dillman 14) Ceramic Spacers by "Jay H. Miller" 15) Removing surface rust from painted metal cabinet by "Tony Schroeder" 16) Looking for Ohmite Z-28's by "Gary Franklin" 17) Re: Looking for Ohmite Z-28's by "RJ Mattson" 18) Z-28 by Paul Monroe 19) Tower sleeve bearings by John Sehring 20) Re: Tower sleeve bearings by Al Parker ---------------------------------------------------------------------- Message-ID: <865D7B6DF2D04A86A2F2599EED0F4F2B@boudreaux> From: To: Old Tube Radios Subject: What Receivers? Date: Sat, 15 May 2010 09:34:25 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01CAF411.CEBA7CF0" This is a multi-part message in MIME format. ------=_NextPart_000_000D_01CAF411.CEBA7CF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable What are the receivers in these photos? They look very "National," but odd. 350353917058 ------=_NextPart_000_000D_01CAF411.CEBA7CF0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ------=_NextPart_000_000D_01CAF411.CEBA7CF0-- ------------------------------ Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Subject: RE: What Receivers? Date: Sat, 15 May 2010 09:45:19 -0500 Message-ID: From: "Singley, Rodger" To: Old Tube Radios Looks like the early National NC-200 to me. Rodger WQ9E -----Original Message----- From: owner-boatanchors@theporch.com on behalf of arc5@ix.netcom.com Sent: Sat 5/15/2010 9:34 AM To: Old Tube Radios Subject: What Receivers? =20 What are the receivers in these photos? They look very "National," but odd. 350353917058 ------------------------------ Message-ID: <4BEEB97E.3030100@comcast.net> Date: Sat, 15 May 2010 08:10:54 -0700 From: Chuck McGregor MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: What Receivers? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Yes, one of the NC-2-40 versions. Possibly with an extra switch or jack added in the lower right corner of the front panel. --Chuck N7RHU On 5/15/2010 7:45 AM, Singley, Rodger wrote: > Looks like the early National NC-200 to me. > > Rodger WQ9E > > > -----Original Message----- > From: owner-boatanchors@theporch.com on behalf of arc5@ix.netcom.com > Sent: Sat 5/15/2010 9:34 AM > To: Old Tube Radios > Subject: What Receivers? > > What are the receivers in these photos? > They look very "National," but odd. > 350353917058 ------------------------------ Message-ID: <4BEECFBC.6090007@comcast.net> Date: Sat, 15 May 2010 09:45:48 -0700 From: Chuck McGregor MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: What Receivers? -Correction Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 5/15/2010 8:10 AM, Chuck McGregor wrote: > Yes, one of the NC-2-40 versions. Possibly with an extra switch or jack > added in the lower right corner of the front panel. Blowing up the photo for closer examination suggests that it is not a jack or switch on the lower right corner, but a Pan Am nameplate, possibly like this one: http://s225.photobucket.com/albums/dd2/cbmcg/?action=view¤t=PanAmnameplate.jpg --Chuck ------------------------------ MIME-Version: 1.0 Date: Sat, 15 May 2010 18:34:19 -0600 Message-ID: Subject: Heathkit sb221 schematic print From: ray jefferson To: Old Tube Radios Content-Type: text/plain; charset=ISO-8859-1 Greetings: after much trying, I admit I cannot get decent copy of the schematic for the Heathkit 221 from my computer! Isn't there anyone out there who can help mout with a printed copy of the 221? There are enough changes in the 220 and 221 that I do need the 221 instead of trying to get by with the 220!. Sure will appreciate any help offered and gladly pay for time and expense. Thanks for your consideration. Ray Jefferson w7fni since.......1934 11854 Hwy. 75 Hailey, Idaho 83333 ------------------------------ Message-ID: From: "Sandy" To: Old Tube Radios Subject: Re: What Receivers? Date: Sat, 15 May 2010 22:15:31 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit Looks like a version of the National NC-200. A earlier version of the NC-2-40D. 73, Sandy W5TVW ----- Original Message ----- From: To: "Old Tube Radios" Sent: Saturday, May 15, 2010 9:34 AM Subject: What Receivers? What are the receivers in these photos? They look very "National," but odd. 350353917058 -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.819 / Virus Database: 271.1.1/2876 - Release Date: 05/15/10 13:26:00 ------------------------------ Message-ID: <4BEFF51D.1040309@kd5byb.net> Date: Sun, 16 May 2010 08:37:33 -0500 From: Ben Hall MIME-Version: 1.0 To: Old Tube Radios Subject: R-390A progress... Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Good morning all, Spent a good portion of yesterday working in the R390A. Even with all of the problems I'm about to describe, I foolishly couldn't resist powering it up and managed to receive WWV on ONE FOOT of wire inside my shop. The problem cap in the IF deck was replaced with a modern MPP 600VDC cap. The old VitaminQ that was there tested fine up to its rated voltage so it didn't need replaced, but I feel better knowing that it has been replaced. Mechanically, I found some of the slug-rack rollers to be gummed up, so those got cleaned, worked free, then all the lube points received a drop of synthetic oil from a syringe with a large needle. This received already tuned pretty easy, but did get slightly better after lubing. The set still has a squeaky groan as I change bands from one of the slug racks. I believe a core is dragging on its form, making the noise, but I'm hesitant to do anything to the core or the form. I do have some dry film lube that would probably work, but I'd hate to have it NOT work and have to replace the slug or the coil. I turned the beast over and inspected the audio deck. I replaced the 8uF cap there that is a problem, and again, while the one I took out was obviously corroded, it tested fine on the cap checker. Go figure. Next to the power supply / audio bypass electrolytics. Wow. On the three section unit, two of the sections had basically NO capacitance. The third was around 40 uF, but quite leaky. The two section unit was also quite leaky. I searched my parts inventory for a few octal bases (or for useless tubes that I could steal the bases from) to make some "field expedient" (read: ugly!) replacements to get the set going. Didn't find any one that I wanted to sacrifice, so I decided to just rebuild the electro's. I've tried this before in another R-390A and it was a disaster. This time, it wasn't! ;) Sawed the cans open with a micro hobby saw (much better than a hacksaw!) and managed to grab the inner most wrapping of the cap with a drywall screw, and the whole guts telescoped out like a child's toy. Melted out most of the tar with some gentle heating from a torch (plop!) and soaked the cans in kerosene as I had some leftover from the Winter heating season. I was pleased with the results. The cans are quite clean. Next onto how to make the connections from the cap base to the new caps. A guy online (lost the page so I can't give him credit) drills the crimped risers for 4-40 and inserts little brass screws to give him something to solder. 4-40 looked too big to me, so I did the same with 2-56 screws, but made from steel. Each pin was drilled (kinda tricky) and received a screw and a nut. I didn't tap these, just used the screw as a tap. Worked fine. The screw was inserted as far as it could go, then locked with the nut. Then I cut off the screw head, and ground it flush with the nut. Out came the big soldering iron and each nut was tinned. One thing I fret over long-term is the availability of high voltage capacitors. With voltages in electronics seemingly going lower and lower - first B+, then +/-15, then +5, then +3.3, and now I believe 1.8 being common with some processors using less than a volt, how long are the cap makers going to make 450 VDC caps? Strangely, cruising Mouser and Digikey, I found a bigger selection of HV caps than I remember ever seeing. The only thing I can think is that maybe switchers are using a dizzying array of these things? At any rate, something is using them and I'm thankful for it. :) The last time I tried doing this, I remember having trouble fitting three caps into a can. They were too wide to get three abreast in the can, so I had to stagger them vertically. I won't have to do that this time, as due to the large array of HV electros at Mouser, I found ones of less than half inch in diameter that can fit three abreast in the can. This made me quite happy. Now to sit back and await the BBT (big brown truck) with my caps to finish the process. I also installed an in-rush limiter. Yeah, I know there has been a lot of debate here recently about the merits of these and if or not they simply protect the fuse and do nothing else. I've used these before and agree that may be the case, but with the limiter you don't get that "thunk" when you hit the power switch and the set seems to come up to voltage slowly in a few seconds. It just seems more gentle than hitting everything with 130 VAC. Next will come replacement of the RF Gain control, as it has a really bad section near full gain that's very annoying. thanks and 73, ben, kd5byb -- Ben Hall, kd5byb@kd5byb.net - ALWAYS OUTNUMBERED, NEVER OUTGUNNED. ------------------------------ Date: Sun, 16 May 2010 08:10:11 -0600 To: Old Tube Radios From: Jack Harper Subject: Re: R-390A progress... Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1"; format=flowed Content-Transfer-Encoding: quoted-printable Message-Id: <20100516150501.71777981F8A@minime.theporch.com> At 07:37 AM 5/16/2010, Ben Hall wrote: >Good morning all, > >Spent a good portion of yesterday working in the R390A. Ben - It is great to see some interesting traffic on the BA List again :) Regards, Jack, W=D8YJ ("Friend to all things Hammarlund") Evergreen, Colorado USA ------------------------------ Message-Id: <6.2.1.2.2.20100516142310.039915a0@pop-server.nc.rr.com> Date: Sun, 16 May 2010 14:23:29 -0400 To: Old Tube Radios From: john Subject: Re: R-390A progress... Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1"; format=flowed Content-Transfer-Encoding: quoted-printable And good to see Bone Yard Ben again too :-) John K5MO At 10:10 AM 5/16/2010, Jack Harper wrote: >At 07:37 AM 5/16/2010, Ben Hall wrote: >>Good morning all, >> >>Spent a good portion of yesterday working in the R390A. > > >Ben - It is great to see some interesting traffic on the BA List again :) > >Regards, > >Jack, W=D8YJ ("Friend to all things Hammarlund") >Evergreen, Colorado USA > ------------------------------ Mime-Version: 1.0 Message-Id: Date: Sun, 16 May 2010 11:30:27 -0700 To: Old Tube Radios From: Scott Robinson Subject: Re: R-390A progress... Content-Type: text/plain; charset="us-ascii" ; format="flowed" Folks, Well, my R-390A is on the bench after a 10 year hiatus. Fist order of business is audio mods: for those interested, I have modified the line output for wide frequency response and low distortion, no new tube sockets or extra holes required. Details available for those interested. I'm now working on the speaker output, and I expect to add only one tube, in the space soon to be vacated by the 600 ohm speaker output transformer. Now to the other reason it's on the bench: it's deaf. All bands now work, after one new crystal from Fair Radio. The sensitivity varies. The IF amp is pretty noisy, with an input sensitivity at the little connector of about 30 uV for 10 dB s/n ratio. Has anyone else measured this, and what did you get? The RF deck end gain seems to be about x5, which is not unreasonable. Thus, the IF amp needs to be quieter for good receiver sensitivity. I sincerely hope *not* to have to take the RF deck out; I did that before and checked all the resistors and replaced all caps. All help gratefully received! Peace, Scott ------------------------------ Mime-Version: 1.0 Message-Id: Date: Sun, 16 May 2010 10:53:55 -0700 To: Old Tube Radios From: Scott Robinson Subject: Re: R-390A progress...and 450V cap availability Content-Type: text/plain; charset="us-ascii" ; format="flowed" Hi Ben, The reason that you can still get 400 V and 450V electrolytics is that every single line-operated switching power supply first rectifies the line with a bridge rectifier. At 265V, the maximum high line voltage for 230 or 240V countries, that will generate 375 V DC, so you need the HV caps. Unless the 80% of the world that runs on 230VAC changes its mind (unlikely...) 400V and 450V caps are here to stay. Nearly all such supplies are rated to work on all world voltages, from 100V (Japan) up to 240V. Supplies with the misnamed feature "power factor correction" typically have a very small first filter cap, usually about 1 uF, followed by a switching process (boost converter) that makes 400V to run the main switching regulator. Here again you need a 450V cap. Whew! We're in luck. Also to our advantage is the ready availability of regulators and low voltage caps designed to make, for instance 2,5V--nice for building a hum-free audio amp with 2A3s and so forth. Peace, Scott ------------------------------ Message-ID: <4BF042BF.8010301@kd5byb.net> Date: Sun, 16 May 2010 14:08:47 -0500 From: Ben Hall MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: R-390A progress... Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi Scott, I'm very interested in hearing about your modification! Please share... I'm afraid I'm not much help with the low sensitivity problems... thanks and 73, ben, kd5byb On 5/16/2010 1:30 PM, Scott Robinson wrote: > Well, my R-390A is on the bench after a 10 year hiatus. Fist order of > business is audio mods: for those interested, I have modified the line > output for wide frequency response and low distortion, no new tube > sockets or extra holes required. Details available for those interested. > > > -- Ben Hall, kd5byb@kd5byb.net - ALWAYS OUTNUMBERED, NEVER OUTGUNNED. ------------------------------ Message-ID: <20179234.1274124264981.JavaMail.root@elwamui-chisos.atl.sa.earthlink.net> Date: Mon, 17 May 2010 15:24:24 -0400 (EDT) From: Richard Dillman To: Old Tube Radios Subject: Reminder: KSM on Tomorrow With Multiple Ships Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Here's a reminder about the on the air event to take place tomorrow, Tuesday 18 May, beginning at 1000pdt/1700gmt. SS JERENIAH O'BRIEN/KXCH, which will be on its Sacramento River cruise, and SS RED OAK VICTORY/KYVM, Richmond, CA to be on the air and communicating on 500kc and 425kc with MRHS coast station KSM. SS AMERICAN VICTORY/KKUI in Tampa, FL. KKUI, using its restored radio gear, is a regular customer of KSM, putting in a QSA5 signal on 12Mc. Don suggested that KKUI and KYVM attempt a ship-to-ship contact on 12552kc. Steve Hawes of KYVM agreed to the attempt. Those with the interest and the capacity may wish to have both the KSM frequencies and 12552kc available with the hope of being able to hear one of both ships. As always, KSM will key all transmitters when in contact with a ship so listeners on any frequency will be able to hear at least one side of the exchange. KSM transmitting frequencies are (in kc): 426 500 4350.5 6474.0 8438.3 12993.0 16914.0 22445.8 KSM monitors ITU channel 3 for calls from ships. The ITU channel 3 frequencies are (in kc): 4184.0 6276.0 8368.0 12552.0 16736.0 22280.5 Amateur station K6KPH will be guarding its normal frequencies for calls from stations with signal reports or other traffic. K6KPH guards: 3550 7050 14050 21050 As always QSLs and reception reports may be sent to the QSL Mistress at: Denice Stoops, QSLM Box 381 Bolinas, CA 94924 USA See the MRHS Web site (http://www.radiomarine.org) for full information. If you are not a member of our email distribution list and would like to receive information like this directly just send an email message to radiomarine-subscribe@yahoogroups.com. VY 73, RD ================================= Richard Dillman Chief Operator, Coast Station KSM Maritime Radio Historical Society http://www.radiomarine.org ================================= ------------------------------ Mime-Version: 1.0 Message-Id: Date: Mon, 17 May 2010 17:43:55 -0500 To: Old Tube Radios From: "Jay H. Miller" Subject: Ceramic Spacers Content-Type: text/plain; charset="iso-8859-1" ; format="flowed" Content-Transfer-Encoding: quoted-printable Does anybody have three cylinder ceramic insulators (spacers/pillars): 3/8" diameter x 1/2" long, 6-32 female threads on both ends. That they would part with? Thanks! *********** jay@kk5im.com *********** Jay H. Miller, KK5IM Dallas, Texas NRA * ARRL * DXCC * S.A.S.S. #34,692 32=B0 AASR * MVPA #25,180 Website: http://www.kk5im.com ***** Proud to be 100% Macintosh since 1984! ***** ------------------------------ Message-ID: <83C48A5AFDAB47929FAF7797AAE39B55@TONY> From: "Tony Schroeder" To: Old Tube Radios Subject: Removing surface rust from painted metal cabinet Date: Tue, 18 May 2010 15:52:57 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01CAF6A2.2FB31200" This is a multi-part message in MIME format. ------=_NextPart_000_0008_01CAF6A2.2FB31200 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Gang, I have a nice National HRO-5 that saw a little bit too much of an = unheated Ohio storage unit. :) It's developed a layer of very light rust = on the surface of the paint, though none has shown up on the chassis. = I'm thinking of using a technique I've applied successfully to remove = light rust from firearms, namely using bronze wool and a bit of oil to = gently scrub away the rust, but I'm curious to know if any of you have = done otherwise and been successful. Thanks, Tony W8HRO ------=_NextPart_000_0008_01CAF6A2.2FB31200 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ------=_NextPart_000_0008_01CAF6A2.2FB31200-- ------------------------------ Message-ID: From: "Gary Franklin" To: Old Tube Radios Subject: Looking for Ohmite Z-28's Date: Wed, 19 May 2010 10:16:00 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01CAF73C.47D7BDA0" This is a multi-part message in MIME format. ------=_NextPart_000_0005_01CAF73C.47D7BDA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I have a homebrew transmitter project which needs a few RF chokes. = Looking for Ohmite Z-28 chokes. Please let me know if you can help. Thanks Gary K8BKB ------=_NextPart_000_0005_01CAF73C.47D7BDA0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ---REMAINDER OF MESSAGE TRUNCATED--- * * This post contains a forbidden message format * * (such as an attached file, a v-card, HTML formatting) * * Mail Lists at theporch.com only accept PLAIN TEXT * * If your postings display this message your mail program * * is not set to send PLAIN TEXT ONLY and needs adjusting * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ------=_NextPart_000_0005_01CAF73C.47D7BDA0-- ------------------------------ Message-ID: <208375DA4E714B6EBF0B3B9C931BEABE@Compaq2200> From: "RJ Mattson" To: Old Tube Radios Subject: Re: Looking for Ohmite Z-28's Date: Thu, 20 May 2010 08:29:37 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Hi Gary Ohmite made the same chokes for all the vhf ham bands. There is an article in the 1960s era QST to make rf chokes for the higher bands. They are rather easy to make if you cannot find z-28s. Presently, the ARRL site is having problems and I could not access the back issues. bob...w2ami x wn2ami 1962 ----- Original Message ----- From: "Gary Franklin" To: "Old Tube Radios" Sent: Wednesday, May 19, 2010 10:16 AM Subject: Looking for Ohmite Z-28's I have a homebrew transmitter project which needs a few RF chokes. Looking for Ohmite Z-28 chokes. Please let me know if you can help. Thanks Gary K8BKB ------------------------------ Message-ID: <4BF54607.1010602@gmail.com> Date: Thu, 20 May 2010 09:24:07 -0500 From: Paul Monroe MIME-Version: 1.0 To: Old Tube Radios Subject: Z-28 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit These chokes are still available from RF Parts in San Mateo http://www.rfparts.com/choke.html#highrfsingle Hope this helps, Paul W9MEH ------------------------------ Message-ID: <793626.91090.qm@web45604.mail.sp1.yahoo.com> Date: Sun, 23 May 2010 15:42:30 -0700 (PDT) From: John Sehring Subject: Tower sleeve bearings To: Old Tube Radios MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Been looking at towers, new & used. Delhi is by far the most common tower in Canada. They have a line of guyed towers which have a "sleeve bearing up to 1.5 inches" on the top of the "top" section, see: http://www.wade-antenna.com/Wade/GN.htm I can't get any more info than that. Is this kind of bearing useable with a rotator? It looks to be made of a short piece of vertical tubing welded to the top of the section, where the three legs come together. I wonder how clearance is achieved between the inside of this sleeve and the outside of the mast from the rotator which runs up through it to the antenna? If the mast wasn't turned for a while, could not rust/corrosion build up in there? If the mast & sleeve sizes weren't closely matched wouldn't there be some sideways slop? Of course much finer would be a tower with a thick plate on top onto which a bearing could be attached to the mast running through it. That is a different style of Delhi self-supportinga tower called "DMX". As always thanks for you feedback. --John WB0EQ/VE6 ------------------------------ Message-ID: <4BF9B8A5.2090502@ec.rr.com> Date: Sun, 23 May 2010 19:22:13 -0400 From: Al Parker MIME-Version: 1.0 To: Old Tube Radios CC: Old Tube Radios Subject: Re: Tower sleeve bearings Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi John, That tower looks very similar to ones availbale "down here". I had some 10-20 yrs ago from a co. in Ohio, "Shelby" I think, that looked very similar to what's shown there. The "bearing" is just a steel sleeve, a piece of pipe or tubing, with maybe 1-1/2" I.D. It's not a real bearing, and maybe even has a boss or two that's drilled & tapped so the buyer can insert a mast and bolt it tight. You're right, if the mast from your lower mounted rotator is smaller in dia., there will be some lateral movement, but not enough, in the trigonometry of things, to matter much. It's not really a bearing surface, just a guide for the mast from your rotator. I operated that way for a long time, in several locations. A plate with a really bearing is much better, but not necessary for medium sized antennas. I used a relatively small Mosley TA-33 tribander, still do, but a different tower setup. Hope that's some help. 73, Al, W8UT www.boatanchors.org www.hammarlund.info "There is nothing -- absolutely nothing -- half so much worth doing as simply messing about in boats" Ratty, to Mole On 5/23/2010 6:42 PM, John Sehring wrote: > Been looking at towers, new& used. Delhi is by far the most common tower in Canada. > > They have a line of guyed towers which have a "sleeve bearing up to 1.5 inches" on the top of the "top" section, see: http://www.wade-antenna.com/Wade/GN.htm > > I can't get any more info than that. Is this kind of bearing useable with a rotator? It looks to be made of a short piece of vertical tubing welded to the top of the section, where the three legs come together. I wonder how clearance is achieved between the inside of this sleeve and the outside of the mast from the rotator which runs up through it to the antenna? > > If the mast wasn't turned for a while, could not rust/corrosion build up in there? If the mast& sleeve sizes weren't closely matched wouldn't there be some sideways slop? > > Of course much finer would be a tower with a thick plate on top onto which a bearing could be attached to the mast running through it. That is a different style of Delhi self-supportinga tower called "DMX". > > As always thanks for you feedback. > > --John WB0EQ/VE6 > > > > > > > ------------------------------ End of BOATANCHORS Digest 4334 ******************************