I realized my misinterpretation of your VFO problem, with the "skewed" dial indication, after I read the replies. Funny, the dial must have been that way from day one. Have fun, George KC
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of russ dworakowski Sent: Wednesday, January 08, 2003 11:48 PM To: [email protected] Subject: RE: [AMRadio] DX-100 vfo Thanks for your input Geprge, but you don't get it- the VFO tracks "tunes" reverse- it is not drifting. I think I have the dial out 180 degrees. Russ >From: "George Pritchard" <[EMAIL PROTECTED]> >Reply-To: [email protected] >To: <[email protected]> >Subject: RE: [AMRadio] DX-100 vfo >Date: Tue, 7 Jan 2003 15:25:40 -0500 > >DX100 VFO Troubles: >Drifting up during transmission: Line voltage drop during plate voltage >turn >on with 600 watts pulled from the outlet may the problem. Check by first >using the spot switch listening to the beat freq on the receiver. Then, >turn >on the plate voltage with transmitter fully loaded, and monitor the drift. >If the filaments in the oscillator drops in voltage and slightly cools off >the tube, the oscillator will drift! See if the oscillator returns to the >original frequency when the plate switch is turned off. Cure: Use a variac >to keep the voltage at >115 VAC during transmit. Or create a DC regulated >supply for the filament string. Anything much lower than 115VAC and the >emissions on the 12BY7 / 5763 and 6146s drops also. You may see this as >gradual drop-off of grid drive during transmit... especially on TEN meters. >I also rewired my VFO with heavy #14 copper. This was mechanically >superior >to the flimsy wiring that can cause drift and microphonics. Here is the big >stability problem: Jumping during VFO freq adjustment on TEM meters. The >VFO >main variable has a rear ball bearing to support the cap shaft. It oxidizes >and becomes erratic. I tried to clean it, but it was never perfect and >always degraded again. I finally REMOVED THE DAM BEARING THING and the >problem was solved. The bearing is not needed as I initially thought. The >shaft is very stable without it. I hope some of this helps. >George AB2KC > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] Behalf Of russ dworakowski >Sent: Tuesday, January 07, 2003 1:53 PM >To: [email protected] >Subject: Re: [AMRadio] DX-100 vfo > > >To the group: I am having difficulty witha different VFO- a VF-1 >or same as used in a DX-100. I know you guys are talking CE20- just a >question- my VFO is tracking reverse in frequency- like when you go down >in frequency on the display, it is actually going up in frequency. >Is it possible that the end point adjustments are so far off that they >could cause this? Russ > > > > > > > >From: Gary Schafer <[EMAIL PROTECTED]> > >Reply-To: [email protected] > >To: [email protected] > >Subject: Re: [AMRadio] "Reply" button got me... > >Date: Sun, 05 Jan 2003 14:46:35 -0500 > > > >Hi Larry and others, > > > >I too have a 20A. Have had several over the years. I found that to get >good > >output on 40 meters that the 1625 has to be in very good shape. Being >just > >a > >little weak makes a big difference. > > > >Also you need to adjust the padding coil (miniductor stock) that is >across > >the > >1625 tank coil in the vfo. You adjust it by spreading the turns on one >end. > >If I > >remember right, the padding capacitor under the chassis needs to be >peaked > >on 80 > >or 20 meters. The other bands are adjusted by adjusting the miniductor > >coils for > >maximum output. (It doubles or triples for other bands) It takes some > >messing > >with to get them right as the Q is pretty high. When you replace the top > >cover on > >the vfo things change so you have to compensate for that when adjusting. > >I watched the output of the transmitter (at less than full power) on a > >meter > >while adjusting the coils. Then watching how much it changes with the > >cover, you > >can get a feel for how much you need to adjust it in the opposite >direction > >so it > >will be right with the cover on. Adjusting the coupling loop (knob on >front > >panel) will detune the tank a little too on 40 meters. > > > >On one vfo that I have I tried slug tuned coils in place of the >miniductor > >stock > >to see if they could be substituted. I found that the slug tuned coils >in > >place > >of the miniductors did not give near as much output on the vfo so that >was > >abandoned . > > > >I also tried to use a higher harmonic for 10 meters and shift the vfo >with > >an > >additional padder capacitor (similar to what is done for 15 meters). I >had > >a > >spectrum analyzer to watch all the harmonics at once but found that I >could > >not > >get enough isolation. Some of the lower harmonics would end up in the > >output. I > >got it to work but tuning was very tricky and if not looking at the > >spectrum > >analyzer, the wrong harmonics would get right through the 20A. I gave up >on > >that > >idea. > > > >I do have a vfo with the 10 meter kit in it. The crystal oscillator in it > >is run > >directly from the 20A's high voltage. When keying the transmitter that > >voltage > >drops some and the crystal oscillator starts to drift. I think that I >tried > >running it from the regulated 105 volts one time but that dropped the > >output too > >low. I have never gotten back to it to try and solve the drift problem. > >Other > >than that it works pretty well on 10. > > > >I also have a Phase master vfo that I have yet to hook up. It is built on > >the 458 > >parts but rather than use harmonics they have separate crystals and > >heterodyne > >for the other bands. It may double on one band, I can't remember. The > >schematic > >of it is in Stoners SSB handbook. > > > >73 > >Gary K4FMX > > > > > > > >Larry Szendrei wrote: > > > > > Mike et. al., > > > > > > My CE20A has about 1/2 the output on 40M as it has on the other bands > > > (160, 80, 20, & 15) in spite of the fact that the CE mods to cure this > > > in the VFO-458 have been implemented. As I recall the VFO output is > > > tripled for 40M, and only doubled or on the fundamental for the other > > > bands. My VFO doesn't have 10M capability, so have no experience with > > > 10M on this rig. > > > > > > 73, > > > -Larry/NE1S > > > > > > MIke Wells wrote: > > > > > > > > I'm enjoying the 20A discussion. I have a 20A that I want to get on > >the air > > > > so keep the messages posted here for the benefit of others. > > > > > > > > Tell me more about the VFO, are you having good luck with it on all > >bands? > > > > I've only got mine working on the low bands, no oscillation on 40 > >meters. > > > > Suggestions? > > > > > > > > 73, > > > > > > > > Mike W0FD > > > > > > > > Subject: [AMRadio] "Reply" button got me... > > > > > > > > Regarding the previous posting to the list: it was unintended. The >old > > > > "reply" button got me again! > > > > > > > > If you're interested, read it. It's part of a discussion Jim Candela > >and > > > > I are having about a vintage SSB exciter, the venerable Central > > > > Electronics 20A. If not, the "Delete" button is much more >predictable > >in > > > > its effects than "Reply." :>) > > > > > > > > 73, and back to AM... > > > > > > > > -Larry/NE1S > > > > > > > > _______________________________________________ > > > > AMRadio mailing list > > > > [email protected] > > > > http://mailman.qth.net/mailman/listinfo/amradio > > > _______________________________________________ > > > AMRadio mailing list > > > [email protected] > > > http://mailman.qth.net/mailman/listinfo/amradio > > > >_______________________________________________ > >AMRadio mailing list > >[email protected] > >http://mailman.qth.net/mailman/listinfo/amradio > > >_________________________________________________________________ >MSN 8 helps eliminate e-mail viruses. 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