Subject: Good News! Date: Wed, 20 Sep 2000 00:03:16 -0400 From: "Woody" To: "Tom Williams" Hi Tom: Your mod fixed the problem, with the following results: Time after turn on. Freq. Control Voltage 3 Min 85.2000008 3.1 V 5 Min 85.2000001 3.54 V 10 Min. 85.1999998 3.715 V 1 Hr. 85.20000004 4.1 V 3 Hr. 85.20000032 (unknown, enclosure is sealed) 4 Hr. 85.20000033 (unknown, enclosure is sealed) It is extremely stable, and settles down very quickly. I am most pleased with this system. I can hardly wait until I can get it installed on the tower in two weeks. The only downside of the mod, is that the output is reduced from 3.5 to 1.5 mw. This is borderline for the brick, since it was designed for 74 MHz. input. Do you think that I would be better off installing the Mav 11 amp, or maybe replacing the 3 dB pad with a 50 Ohm resistor? I only need to get the output up to about 3 mw. Thanks for all that you have done on this design. I think that you should submit it to QEX. I would think that it would be very popular for use on 10 and 24 GHz. It can be used with the DEM transverters, or bricks like you and I are using. I am going to try and cram one inside my IC-271A/ DEM 10 GHz. transverter system. There is not a lot of room, especially with the 4 W PA built-in. It sure would be nice to have this kind of accuracy in a portable rig. Out of curiosity, how much does the Mav 11 and its components add to the cost of the package? Corrections / changes to your documentation: Page 2, paragraph 1.5, last sentence: Change to ".....no effect on the circuit." Page 2, paragraph 1.6, second sentence: Change to "Both of these diodes are attached directly to......" Page 2, paragraph 1.8, second sentence: I would reword to something other than "I will not". Maybe: The boxes can be supplied with out pre-drilled holes if you prefer. Page 3, paragraph 1.8 continued: These small feed-thrus are very easy to break. There is no way to get a reliable ground with the ground tab on the feed-thru. I would recommend that you omit the option, and drill a separate hole for it. Page 4, paragraph 2.1: Change "Jumper XL/C" to "Jumper L/CX" to match the board. Change "XL/C" to "L/CX" on 5th. line from bottom of page Page 5, paragraph 2.2: Change "#### ma. to ~100 ma with crystal heater hot, more when cold. Clarify test point for control voltage since the article is wrong (not D2) I think that labeling the first two pages of the PLL/VCXO Parts List as the VCXO Parts list, and Page 3 as "PLL Parts List" would eliminate potential confusion for some people. Page 2 of PLL/VCXO Parts List: L1 - "Markings" Change "12 formula is......." to "L1 formula is..." Page 3 of PLL/VCXO Parts List: "C13, C19" I only received one capacitor, and you show the quantity on the list to be "1", but I installed caps at both places on the board. The only other thing that I would worry about is the potential for some people to place the diode backwards on the regulators. Most people assume that when looking at the flat side of the regulator, the input is the lead on the left, rather than on the right. Perhaps a close-up photo of the regulator with the diode installed would eliminate this. Tom, this is very clearly written and well laid out, and I can not imagine someone screwing it up. However, we both know that there are some people who can screw up a rock. BTW, unless you change some photos, save yourself some money and do not send me two more of the photos. 73, Woody KJ4SO ----- Original Message ----- From: "Tom Williams" To: "Woody" Sent: Monday, September 18, 2000 9:19 PM Subject: Re: discovery continued > Woody wrote: > > > > Hi Tom: > > > > I have done extensive testing on my transverter for the past two days. With > > the heater disconnected, the crystal oscillates at 85.2 MHz. > > Yes, but it shouldn't oscillate there unless there is about 5 V on > the control voltage. Considering what you have discovered below, > (it runs at 85.2 with a conrtol voltage of 5 V +/- at room temperature), > it seems that the crystal really is off frequency. > > > The 10 MHz. > > OCXO operates at 10.000000050 MHz. I installed the OCXO inside a die-cast > > enclosure that is the same size as the two that you sent me, and insulated > > it inside with foam. > > 50 millihertz is pretty amazing. That is beyond the specifications. > I figured it might drift about 1 Hz. > > > > BTW, my Rubidium standard shows 10.0000000005 on my counter, using a 1000 > > sec gate time. I am really surprised that the OCXO is so accurate. Did you > > buy any from the guy that I wrote you about? > > That means that your frequency counter also has a rubidium standard > in it for its clock? Even Rubidiums are at best good to 1 millihertz > at 10 MHz, and your standard compared to your freq counter showed > 1/2 a millihertz difference. > > I bought 3 from him, and last week sent his address to another person > who wants to build the kit, and he still had a few. > > > > The control voltage is a little more than 1.2 volts after 5 minutes of > > warm-up. After the 85.2 MHz. osc. warms up for a couple of hours, the > > voltage rises to approx 4.5 volts. After 4 hours, it rises to approx. 5.2 > > to 5.6 volts, and is pretty stable from then on. > > Well, I put the 85.2 that I have sent to you in a little styrofoam > enclosure with the heater, and it locked at about 5 V in 15 minutes. > This is after the added turn on L1. > Maybe it will loose lock after four hours - I didn't try it for more > than about 1 hour. Perhpas there are other components that are heating > up besides the crystal which are pushing the frequency further. > > > > The 85.2 refference output to the brick LO ***** DRIFTS *******. It varies > > from 85.200000100 to 85.199999998. Those are the extremes that I have > > observed after a 4 hour warm-up. Most of the time it hangs around > > 85.200000005. BTW, these readings are all using the OCXO, not with the > > Rubidium standard. > > Right - the only way that I am convinced about non-standard related > drift is to drive the frequency counter and the circuit from the same > 10 MHz standard. One way I do it is to drive both from the Rubidium by > driving the freq counter from the Rubidium, and taking the freq counter > 10 MHz output into the circuit. In fact, I can get the same results > without the Rubidium but just driving using the internal freq counter > clock and taking its output to the circuit. When this is done, the > results I get still show some wavering around the target frequency, > with even amounts above and below, and usually I can trace any sudden > changes to some electrical disturbance in the power source. > > > > I will make the mod that you suggested tomorrow, and let you know the > > results. When I get the second crystal, I will install it and test it > > thoroughly as well. > > > > BTW, do you know that you used a different gauge wire for L1 than the > > original QEX article? > > Yes, but my calculations show almost no difference in inductance. Maybe > I goofed... > > > > 73, > > > > Woody > > KJ4SO > > > > Tom W. >