20100524.ba v04_n335.bam.20100524 >From ???@??? Mon May 24 14:38:21 2010 -0500 Date: Mon, 24 May 2010 14:38:16 CST From: Old Tube Radios To: Old Tube Radios Subject: BOATANCHORS digest 4335 Message-Id: <20100524203816.A548D9E9FC4@minime.theporch.com> BOATANCHORS Digest 4335 Topics covered in this issue include: 1) Re: Tower sleeve bearings by "Wilson Lamb" 2) Re: Tower sleeve bearings by WA5JCI 3) Re: Tower sleeve bearings by "K0DAN" 4) Re: Tower sleeve bearings by "Bob Moody" 5) Re: Tower sleeve bearings by john 6) Re: Tower sleeve bearings by Al Parker 7) Re: Tower sleeve bearings by "K0DAN" 8) Hallicrafters 50 kHz IF by John Sehring ---------------------------------------------------------------------- Message-ID: <284435D30B164EEFADD53B3C6C6705CB@wilsonspc> From: "Wilson Lamb" To: Old Tube Radios Subject: Re: Tower sleeve bearings Date: Sun, 23 May 2010 20:37:59 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit I'd look for some sort of plastic pipe/tubing to make a liner/wera surface, if there's room. You might even be able to use a piece of flexible sheet stock, with some sort of collar/retainer at the end(s). Wilson W4BOH ----- Original Message ----- From: "Al Parker" To: "Old Tube Radios" Cc: "Old Tube Radios" Sent: Sunday, May 23, 2010 7:22 PM Subject: Re: Tower sleeve bearings > 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 >> >> >> >> >> >> >> > ------------------------------ Message-ID: <890727.63434.qm@smtp105.sbc.mail.mud.yahoo.com> Date: Sun, 23 May 2010 21:03:46 -0500 To: Old Tube Radios From: WA5JCI Subject: Re: Tower sleeve bearings Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed I turned a sleeve from water pipe on a lathe and left a lip on the outside so it wouldn't fall through. de Pete WA5JCI At 07:37 PM 5/23/2010, Wilson Lamb wrote: >I'd look for some sort of plastic pipe/tubing to make a liner/wera >surface, if there's room. >You might even be able to use a piece of flexible sheet stock, with >some sort of collar/retainer at the end(s). >Wilson >W4BOH >----- Original Message ----- From: "Al Parker" >To: "Old Tube Radios" >Cc: "Old Tube Radios" >Sent: Sunday, May 23, 2010 7:22 PM >Subject: Re: Tower sleeve bearings > > >>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 >>> >>> >>> >>> >>> >>> ------------------------------ Message-ID: <019001cafae5$773ece60$6601a8c0@K0DAN> From: "K0DAN" To: Old Tube Radios Subject: Re: Tower sleeve bearings Date: Sun, 23 May 2010 20:16:29 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit As someone else said if you have a light load (low weight, small turning radius) it probably doesn't matter much. But otherwise all the weight of the mast + antenna(s) rests on the rotor, which could be damaging over time. Also the lateral forces of wind + ice will tend to wear the metal (aluminum tower? steel mast?) at the top and inside the "bearing". And if the boom length(s) is of any size, you will have very large start/stop torques which will all show as twist on your rotor. GL es 73 Dan K0DAN ----- Original Message ----- From: "John Sehring" To: "Old Tube Radios" Sent: Sunday, May 23, 2010 5:42 PM Subject: Tower sleeve bearings > 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: <0D2ADF07707342E2808C74DABE6D914C@LENOVO8EA8B73D> From: "Bob Moody" To: Old Tube Radios Subject: Re: Tower sleeve bearings Date: Sun, 23 May 2010 21:28:05 -0700 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit RODNEY! ----- Original Message ----- From: "WA5JCI" To: "Old Tube Radios" Sent: Sunday, May 23, 2010 7:03 PM Subject: Re: Tower sleeve bearings >I turned a sleeve from water pipe on a lathe and left a lip on the outside >so it wouldn't fall through. > > de Pete WA5JCI > > > > > At 07:37 PM 5/23/2010, Wilson Lamb wrote: >>I'd look for some sort of plastic pipe/tubing to make a liner/wera >>surface, if there's room. >>You might even be able to use a piece of flexible sheet stock, with some >>sort of collar/retainer at the end(s). >>Wilson >>W4BOH >>----- Original Message ----- From: "Al Parker" >>To: "Old Tube Radios" >>Cc: "Old Tube Radios" >>Sent: Sunday, May 23, 2010 7:22 PM >>Subject: Re: Tower sleeve bearings >> >> >>>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 >>>> >>>> >>>> >>>> >>>> >>>> > > ------------------------------ Message-Id: <6.2.1.2.2.20100524064033.030f6170@pop-server.nc.rr.com> Date: Mon, 24 May 2010 06:41:45 -0400 To: Old Tube Radios From: john Subject: Re: Tower sleeve bearings Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Go to your Big Box hardware store and find a PVC reducer. It has a shoulder on it and will work fine for this application .... I did the same with the small diameter mast I had in my tower when I lived in NM. John K5MO At 10:03 PM 5/23/2010, WA5JCI wrote: >I turned a sleeve from water pipe on a lathe and left a lip on the outside >so it wouldn't fall through. > >de Pete WA5JCI > > > > >At 07:37 PM 5/23/2010, Wilson Lamb wrote: >>I'd look for some sort of plastic pipe/tubing to make a liner/wera >>surface, if there's room. >>You might even be able to use a piece of flexible sheet stock, with some >>sort of collar/retainer at the end(s). >>Wilson >>W4BOH >>----- Original Message ----- From: "Al Parker" >>To: "Old Tube Radios" >>Cc: "Old Tube Radios" >>Sent: Sunday, May 23, 2010 7:22 PM >>Subject: Re: Tower sleeve bearings >> >> >>>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 >>>> >>>> >>>> >>>> >>>> ------------------------------ Message-ID: <4BFA9160.9030106@ec.rr.com> Date: Mon, 24 May 2010 10:46:56 -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 The rotator is the only thing in the setup that will absorb any torque from wind loading, etc. It produces torque to turn the beam. If there is a brake in the rotator it, rather than the gearing, takes the wind torque. Our "normal" rotators have a ring of bearings (a thrust bearing) that support the weight of the whole assembly if there is no thrust bearing installed to support the mast. An external thrust bearing is not common on our small to medium arrays, the rotators are sized to take it. My present system is a rotating tubular tower that has the rotator at the base, and the whole load of the tower & antenna system is supported on a flange type thrust bearing above the rotator. The rotator takes no load at all, just provides torque to turn and to brake. 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 9:16 PM, K0DAN wrote: > As someone else said if you have a light load (low weight, small turning > radius) it probably doesn't matter much. But otherwise all the weight of > the mast + antenna(s) rests on the rotor, which could be damaging over > time. Also the lateral forces of wind + ice will tend to wear the metal > (aluminum tower? steel mast?) at the top and inside the "bearing". And > if the boom length(s) is of any size, you will have very large > start/stop torques which will all show as twist on your rotor. > > GL es 73 > > Dan > K0DAN > > > ----- Original Message ----- From: "John Sehring" > To: "Old Tube Radios" > Sent: Sunday, May 23, 2010 5:42 PM > Subject: Tower sleeve bearings > > >> 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: <025b01cafb5e$cdfb0c40$6601a8c0@K0DAN> From: "K0DAN" To: Old Tube Radios Cc: "Old Tube Radios" Subject: Re: Tower sleeve bearings Date: Mon, 24 May 2010 10:53:20 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit A thrust bearing bolted to the top of the tower, and bolted laterally to the mast, is always a good thing. It will share the start/stop forces and vertical load. An under-rated rotator, rotor base plate, or tower will take the stresses of wind/ice load and start/stop torque. If all the vertical weight sits on the rotor, the owner better hope it's plumb (esp with wind), else one side of that ring of bearings inside the rotor is gonna get pinched. I agree in principle with what you're saying...but key words are "normal" and "small to medium". I'm speaking from experience, I have a "medium to heavy duty" rotor, and a "medium sized" antenna array, (installed 1999) and am in the middle of a major rotator replacement project cuz the rotor seized up. I went by the mfgr specs during the purchase/install process...after it died, I did the math and discovered all the "medium" verbiage meant nothing, my whole system was below spec! I don't like it, but that's the way it was! Anyway, we're off topic here...I should add that "old tube radios" are used on the antennas referenced herein. ;-) GL es 73 Dan K0DAN ----- Original Message ----- From: "Al Parker" To: Cc: "Old Tube Radios" Sent: Monday, May 24, 2010 9:46 AM Subject: Re: Tower sleeve bearings > The rotator is the only thing in the setup that will absorb any torque > from wind loading, etc. It produces torque to turn the beam. If there is > a brake in the rotator it, rather than the gearing, takes the wind torque. > Our "normal" rotators have a ring of bearings (a thrust bearing) that > support the weight of the whole assembly if there is no thrust bearing > installed to support the mast. An external thrust bearing is not common > on our small to medium arrays, the rotators are sized to take it. > My present system is a rotating tubular tower that has the rotator at the > base, and the whole load of the tower & antenna system is supported on a > flange type thrust bearing above the rotator. The rotator takes no load > at all, just provides torque to turn and to brake. > 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 9:16 PM, K0DAN wrote: >> As someone else said if you have a light load (low weight, small turning >> radius) it probably doesn't matter much. But otherwise all the weight of >> the mast + antenna(s) rests on the rotor, which could be damaging over >> time. Also the lateral forces of wind + ice will tend to wear the metal >> (aluminum tower? steel mast?) at the top and inside the "bearing". And >> if the boom length(s) is of any size, you will have very large >> start/stop torques which will all show as twist on your rotor. >> >> GL es 73 >> >> Dan >> K0DAN >> >> >> ----- Original Message ----- From: "John Sehring" >> To: "Old Tube Radios" >> Sent: Sunday, May 23, 2010 5:42 PM >> Subject: Tower sleeve bearings >> >> >>> 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: <834771.36284.qm@web45615.mail.sp1.yahoo.com> Date: Mon, 24 May 2010 13:38:09 -0700 (PDT) From: John Sehring Subject: Hallicrafters 50 kHz IF To: Old Tube Radios MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable =0A=0A--- On Mon, 5/24/10, John Sehring wrote:=0A=0A> Fro= m: John Sehring =0A> Subject: Re: Hallicrafters 50 kHz IF = transformers - For Sale=0A> To: "k4pf@juno.com" =0A> Date: M= onday, May 24, 2010, 2:28 PM=0A> I called the guy in ER classified but=0A> = he never called back, my nickel!=0A> =0A> I've found a good home for the 50= kHz IF cans elsewhere.=0A> =0A> With your -115, I think you were seeing th= e "first" AGC=0A> with fast time constant fall away quickly & then the=0A> = "second" AGC with slow time constant takes you the rest of=0A> the way to z= ero signal AGC voltage.=0A> =0A> Tnx for tip on its notch filter.=A0 On my = SX-101A &=0A> SX-100 (which have same notch filter as SX-115), I jiggered= =0A> the stops on the shaft of the notch frequency control so it=0A> could = rotate further than normal in both directions.=A0 I=0A> could then notch ov= er a wider frequency range.=0A> =0A> However, I would want to ck the freque= ncy adjustment of=0A> your notch filter.=A0 Someone (who also clips cathode= =0A> R's!) may have mis-aligned it.=A0 You really shouldn't=0A> have the is= sue you do have with ur -115.=A0 The=0A> instructions for that in book are = ok.=0A> =0A> 73 John WB0EQ/VE6=0A> =0A> > =0A> > Hi, John=0A> > =0A> > I w= onder if you still have any of those IF=0A> transformers?=0A> > =0A> > Not = for me, but I see a "wanted" ad in April's =0A> > Electric Radio Magazine, = =0A> > a guy looking for one for an SX-101A.=0A> > =0A> > He said it's P/N = 050-200-735.=0A> > =0A> > "Call Gene, NT6R 304/358-2603"=0A> > =0A> > I hav= e an SX-115, and can vouch for the very=0A> effective=0A> > AGC.=0A> > I ha= d that set up in an comparison with my 75S-3C,=0A> and=0A> > much=0A> > pre= ferred the SX-115 for listening to SSB nets.=0A> > =0A> > The AGC character= istic showed up in c.w., when I used=0A> an=0A> > electronic=0A> > TR switc= h.=A0 Key down, the S/meter was about 40 over.=0A> > Immediately after keyi= ng, the S/meter would rapidly=0A> fall to=0A> > about S/5,=0A> > than hang = for a few tenths of a second, then fall=0A> away=0A> > toward zero at a slo= wer rate.=A0 It wasn't really=0A> > annoying, but was odd.=0A> > You'd prob= ably want to key the AGC to mute the SX-115=0A> > receiver=0A> > for full b= reak-in, but I was just fooling around to=0A> see how=0A> > it worked.=0A> = > =0A> > Strangely, I found that someone had shorted out a=0A> cathode=0A> = > resistor=0A> > in the audio stage.=A0 It sounded a lot better when=0A> > = restored=0A> > to original.=0A> > =0A> > If you ever do get an SX-115, here= 's a hint for better=0A> A.M.=0A> > reception:=0A> > instead of having the = rejection notch turned to "off",=0A> =0A> > turn it to the other extreme.= =0A> > "Off" on the SX-115=A0 places the notch just on the=0A> > opposite s= ideband =0A> > when you are listening to SSB, but results in a=0A> destruct= ive=0A> > notch=0A> > within the a.m. passband.=A0 Moving it to the other= =0A> > direction gets it=0A> > away from near the center of the a.m. passba= nd.=0A> > =0A> > 73,=0A> > Ed Knobloch=0A> > =0A> > =0A> > ---------- Origi= nal Message ----------=0A> > From: John Sehring =0A> > To:= Old Tube Radios =0A> > Subject: Hallicrafters 50= kHz IF transformers - For=0A> > Sale=A0 =0A> > Date: Sun, 25 Apr 2010 16:3= 8:27 -0700 (PDT)=0A> > =0A> > Oh, forgot...these IF cans are NOS, never use= d!=0A> > =0A> > When I had a Halli SX-101A, my plan was to wire in the=0A> = same=0A> > kind of "dual loop" AGC circuit that the SX-115=0A> had.=A0=0A> = > For that, I needed a 50 kHz IF can.=0A> > Sadly, I never got to do it.=0A= > > =0A> > I handled an SX-115 only once, in 1963 when I was=0A> quite=0A> = > young & relatively inexperienced.=A0 But I do=0A> > remember the -115 as = being very "smooth" in AGC action=0A> &=0A> > clean (low distortion) audio = (probably due to their=0A> use of=0A> > negative audio feedback).=0A> > =0A= > > The 1st AGC loop was derived from the 2nd to last IF=0A> stage=0A> > (a= place of not quite ultimate selectivity).=A0 It had=0A> > fast attack/fast= decay time constants and drove ONLY=0A> the RF=0A> > stage.=0A> > =0A> > T= he 2nd AGC loop was taken from the usual place, a=0A> point of=0A> > maximu= m selectivity, and drove the IF stages per=0A> usual, used=0A> > fast attac= k/slow decay.=A0 (The SX-101A's single loop=0A> AGC=0A> > also controlled t= he 1st mixer, interesting.)=0A> > =0A> > Halli claimed the dual loop AGC im= proved what they=0A> called=0A> > "dynamic selectivity".=A0 A strong signal= somewhat off=0A> > freq (just outside of rx's IF bandpass) would cause=0A>= reduced=0A> > gain only in the RF stage (via the "wider" 1st AGC=0A> > loo= p).=A0 That could reduce cross-modulation=0A> tendencies=0A> > in the RF st= age. =0A> > =0A> > At the same time, the other, "narrower" AGC loop would= =0A> then=0A> > drive the gain of the remaining AGC-controlled IF=0A> stage= s up=0A> > to bring in-bandpass sigs back up.=0A> > =0A> > This kind of AGC= ct. is unusual, no?=A0 Off the top of=0A> > my head, I can't recall any ot= her rx featuring this.=A0=0A> I=0A> > would love to have tried it!=0A> > = =0A> > Oh well, I'm very happy with the really fast, tight,=0A> flat=0A> > = AGC characteristics of my Drake R-4*s and Collins=0A> 75S-3*s=0A> > radios!= =A0 It is really superb even when compared to=0A> some=0A> > of today's rx'= s!=0A> > =0A> > --John=A0 WB0EQ=0A> > =0A> > =0A> > =0A> > =A0 =A0 =A0 =0A>= > =0A> > =0A> > =0A> > =0A> =0A> =0A> =0A> =0A=0A=0A ------------------------------ End of BOATANCHORS Digest 4335 ******************************