UHF R0 Receiver - Revision history

Bryan at 02:48, 1 December 2016

2016-12-01T02:48:21Z

Bryan at 20:17, 25 December 2015

2015-12-25T20:17:23Z

Bryan: /* Final testing */

2015-12-25T20:13:15Z

Final testing

Bryan: /* Change the Module ID */

2015-12-25T20:12:12Z

Change the Module ID

Bryan: /* Image filter */

2015-12-25T20:09:32Z

Image filter

Bryan: /* Image filter */

2015-12-25T18:37:44Z

Image filter

Bryan: /* Low VCO */

2015-12-25T15:51:30Z

Low VCO

Bryan: /* High VCO */

2015-12-25T05:04:17Z

High VCO

Bryan: /* Converting VCO */

2015-12-25T04:54:27Z

Converting VCO

Bryan: /* R0 to R2 */

2015-12-25T01:06:28Z

R0 to R2

← Older revision		Revision as of 02:48, 1 December 2016
Line 417:		Line 417:

	No data on this yet, may be doable VCO will be a problem.		No data on this yet, may be doable VCO will be a problem.
		+
		+	[[Category:Quantar]]

@@ Line 1: / Line 1: @@
 This page covers the UHF Range 0 receiver.  This is a newer design that covers all of R1 (403-433) and the federal band at 380 MHz.
@@ Line 118: / Line 116: @@
 = Conversions =
 Converting the boards to different ranges.  Only R0 to R2 has been preformed, but the others should work almost the same.

@@ Line 321: / Line 321: @@
 === Final testing ===
-Once the preceding modifications have been done it's time to test the receiver module with out the preselctor.
+Once the preceding modifications have been done it's time to test the receiver module without the preselctor.
 With the power off install the RX board back in the metal case and slot it into the Quantar chassis.
@@ Line 404: / Line 404: @@
 |}
-Use the control and metering screen to check the oscillator voltage at each frequency.  Ideally you should be between 2 and 7.5 volts for 438.00-454.00 and 454.25-470.  The other frequencies are there just to find the range of the VCO's as installed.  If your minimum lock voltage is under 1.5v you may want to re-adjust the VCO in question.  If the high frequency is above 8v you may wish to adjust as well.
+Use the control and metering screen to check the oscillator voltage at each frequency.  Ideally you should be between 2 and 10 volts for 438.00-454.00 and 454.25-470.  The other frequencies are there just to find the range of the VCO's as installed.  If your minimum lock voltage is under 1v you may want to re-adjust the VCO in question.  If the high frequency is above 11v you may wish to adjust as well.
 Check the sensitivity of the receiver at all locked frequencies.  With out the preselector installed the sensitivity should be better than -121.5 dBm or .2μV for 12dB SINAD.
-Once this is verified, button it up, install the modified preselector and mark the unit as a R2 modified.
+Once this is verified, button it up, install the modified preselector and mark the unit as a R2 modified receiver.
 Congratulations!

@@ Line 310: / Line 310: @@
 === Change the Module ID ===
-There is one resistor, R2450 by the PLL synth which must be changed to a 3300 Ohm chip to set the RX type to R2.
+Follow the table above and change R2607 and R2606 to 1200 Ohm parts.  These a located by the synthesizer, but not inside it.
 <gallery heights=400px widths=400px mode="packed">
-UHF_RX_R2450_location.jpg| R2450 location
+R0_Rx_Synth_ID_resistors.png| R0 to R2 ID voltage divider.
 </gallery>

@@ Line 228: / Line 228: @@
 Below is real data from a R1 to R2 conversion.  The before data was taken with the shield off making the frequency about 2 mhz lower.  The pink represents the sweet spot of the VCO tuning voltages.  Note this covers both VCO ranges acceptably.
-=== Image filter ===
+=== Image filter & Mixer ===
-The image filter is a low pass filter which prevents the Local Oscillator from radiating out the receiver antenna port.  This may be debatable as to the necessity of this modification as the cutoff of the R0 image filter is still above the maximum operating frequency of 470 MHz.
+The image filter is a low pass filter which prevents the local oscillator from radiating out the receiver antenna port.  This may be debatable as to the necessity of this modification as the cutoff of the R0 image filter is still above the maximum operating frequency of 470 MHz.
 {| class="wikitable"
@@ Line 247: / Line 247: @@
 There is no difference in sensitivity, but all units which I convert I modify this for completeness.
-Below are the parts differences.  All parts are NPO 0805 size ceramic parts.  I remove all the "Discard" parts first and then move the couple parts since the board is already hot.
+Below are the parts differences.  All parts are NPO 0805 size ceramic parts.  I remove all the "discard" parts first and then move the couple parts since the board is already hot.
 {| class=wikitable
-|+ style="text-align: left;" | R1 to R2 parts differences.
+|+ style="text-align: left;" | R0 to R2 parts differences.
-!Part number!!R1!!R2!!Notes
+!Part number!!R0!!R2!!Notes
 |-
-|C2050||9.1 pF||8.2 pF||Discard
+| L2030||10nH||8.2nH||discard
 |-
-|C2051||16pF||13pF||move to C2053
+| ||||||
 |-
-|C2053||18 pF||16 pF||Discard
+| C2050||9.1pf||8.2pf||discard
 |-
-|C2054||8.2 pF||6.8 pF||Move to C2050
+| C2051||16pf||13pf||move to C2053
 |-
-|C2057||18 pF||16 pF||Discard
+| C2053||18pf||16pf||discard
 |-
-|C2059||18 pF||13 pF||Discard
+| C2054||8.2pf||6.8pf||Move to C2050
 |-
-|C2070||5.6 pF||3.3 pF||Move to C2076
+| ||||||
 |-
-|C2076||7.54 pF||5.6 pF||Discard
+| C2057||18pf||16pf||discard
 |-
-|C2079||9.1 pF||5.6 pF||Discard
+| C2059||18pf||13pf||discard
 |-
-|C2083||47 pF||22 pF||Discard
+| C2076||7.5pf||5.6pf||discard
 |-
-|||||||
+| C2083||47pf||22pf||discard
 |-
-|R2449||0 Ohm||0 Ohm||ID Leave
+| C2079||9.1pf||5.6pf||move to C2301
 |-
-|R2450||0 Ohm||3300 Ohm||ID Replace
+| C2070||5.6pf||3.3pf||move to C2076
 |}
@@ Line 282: / Line 293: @@
 <gallery heights=300px widths=300px mode="packed-hover">
 UHF Image Filter case on.jpg| Shield on
-UHF_RX_Image_filter_case_off_R1_to_R2.png | Shield off R1-R2 parts
+RX_R0_Image_filter_case_off_R0_to_R2.png | Shield off R0-R2 parts
 </gallery>
-Using a board pre-heater and hot air wand remove the shield.  It does not go through the board, but be careful you do not over heat it as the inductors will melt.  It's much easier than the VCO shield.  Once off change the parts per the table and reinstall the shield.  Note the orientation of the shield, it's designed with cutouts on the input and output strip-lines.
+Using a board pre-heater and hot air wand remove the shield.  It does not go through the board, but be careful you do not over heat it as the inductors will melt.  It's much easier than the VCO shield.  Once off change the parts per the table/pictures and reinstall the shield.  Note the orientation of the shield, it's designed with cutouts on the input and output strip-lines.
 * Change the parts under the 1st mixer shield per the table and picture below
 <gallery heights=400px widths=400px mode="packed">
-UHF_RX_First_Mixer_board_R1-R2_mod.png | UHF 1st mixer parts moved
+R0_to_R2_RX_First_Mixer_board.png | UHF 1st mixer parts moved
 </gallery>

@@ Line 192: / Line 192: @@
 * removing inductance makes Fr go up.
 * you may elect to move the center frequency lower on the lower VCO and higher on the high VCO if you desire a greater tuning range.  I will not be showing this.
-* Get it close, I'm a perfectionist, but really 1-2 MHz from idea will not matter.
+* Get it close, I'm a perfectionist, but really 2-4 MHz from ideal will not matter.
 * the R0 VCO is clean from 0-12v of steering voltage.
@@ Line 207: / Line 207: @@
 It's normal for the VCO to jump a couple hundred KHZ or so depending on the stability of your power supply. There is no PLL running to lock it.
 Do a sweep (2-10v) and ensure it covers the intended range for the Low VCO (511-527 MHz).  You want the coverage to be in the sweet spot of 2v to 10v, if it's not re-adjust it or grind some off the resonator.  Generally this is not that critical.
 === High VCO ===

@@ Line 219: / Line 219: @@
 Check the Fr on the spectrum analyzer, you want 535 MHz at 6V, it's best to be a bit low (long) with the resonator and then touch up the tuning capacitor with a diamond tip grinder to bring it up the frequency.
 Do a sweep (2-10v) and ensure it covers the intended range for the High VCO (527-543 MHz).  You want the coverage to be in the sweet spot of 2v to 10v, if it's not re-adjust it or grind some off the resonator.  Generally this is not that critical.
@@ Line 224: / Line 227: @@
 Clean it with some solvent and let it dry.
 Below is real data from a R1 to R2 conversion.  The before data was taken with the shield off making the frequency about 2 mhz lower.  The pink represents the sweet spot of the VCO tuning voltages.  Note this covers both VCO ranges acceptably.
 === Image filter ===

@@ Line 171: / Line 171: @@
 [[File:R0_RX_VCO_modification_points.png|center|thumb|widths=300px|heights=300px|UHF R0 RX VCO test points]]
 Hook up to the VCO as shown, we'll do the Low VCO first since it's got a resonator in it.
@@ Line 183: / Line 185: @@
 * The VCO will be 73.35 MHz higher than the intended receiver frequency
 * '''the sweet spot for the VCO steering voltage is 2-10 v'''
-* each VCO is designed to cover half the range of the quantar.
+* each VCO is designed to cover half the range of the Quantar.
-* The Exciter will change VCO's when it hits the range's center frequency +25khz (UHF R2 is MHz) . You can verify this my looking at the steering voltage in the exciter as you change frequencies. A test config file (Codeplug) makes this easy.
+* The Exciter will change VCO's when it hits the range's center frequency +25khz (UHF R2 is 454.250 MHz) . You can verify this by looking at the steering voltage in the exciter as you change frequencies. A test config file (Codeplug) makes this easy.
-* with the shield on they move up about 2.5 MHz
+* from hot to cold Fr changes about 1 MHz. Hotter makes Fr go down, cool makes it go up.
-* from hot to cold Fr changes about 1.5 to 2 MHz. Hotter makes Fr go down, cool makes it go up.
+* grinding half the tuning cap off makes Fr go up about 20 MHz.  It's very sensitive.
 * removing capacitance makes Fr go up.
 * removing inductance makes Fr go up.
 * you may elect to move the center frequency lower on the lower VCO and higher on the high VCO if you desire a greater tuning range.  I will not be showing this.
 * Get it close, I'm a perfectionist, but really 1-2 MHz from idea will not matter.
-* at higher steering voltages (>9v) the VCO may get dirty.  This is normal.
+* the R0 VCO is clean from 0-12v of steering voltage.
-Put 5.0v on the steering line and note the frequency on the spectrum analyzer.  You can sweep it from low to high and check the coverage is correct per the table above (it will be about 2MHz higher with the case off).
+With the voltage on the steering line you should see a Fr of about 495 MHz on the spectrum analyzer.
-We're going to align it for a center frequency of 517 MHz. The reason for this is the lower VCO covers 511-527, making the center 519, but with the shield off we will see the CF be ~2 MHz lower. The shield adds capacitance to the circuit and this ups the resonate frequency.
+It's normal for the VCO to jump a couple hundred KHZ or so depending on the stability of your power supply. There is no PLL running to lock it.
-With the voltage on the steering line, cut a 75 mill strip of .250 copper foil. It's not critical, you'll be adjusting it. Place it on the VCO Trombone to short out part of the strip-line. You can safely monitor the output of the VCO and move this at the same time. '''It's best to go lower than the center frequency we want. (515 MHz is a good point)'''. Once you are within a few MHz, let the board cool. You'll find the Fr rising as it cools.
+Do a sweep (2-10v) and ensure it covers the intended range for the Low VCO (511-527 MHz).  You want the coverage to be in the sweet spot of 2v to 10v, if it's not re-adjust it or grind some off the resonator.  Generally this is not that critical.
-while monitoring the VCO output on the spectrum analyzer, use a diamond tip Dremmel grinder and remove some of the high impedance end tuning cap on the VCO. Go a very little at a time, it makes a big difference. Use this to bring the VCO frequency up to 517 MHz on the dot. It's normal for the VCO to jump a couple hundred KHZ or so depending on the stability of your power supply. There is no PLL running to lock it.
+=== High VCO ===
-Do a sweep according the the service manual and ensure it covers the intended range for the Low VCO (again subtract 2 MHz from the intended range with the case off).  You want the coverage to be in the sweet spot of 2.5v to 7.5v, if it's not re-adjust it.
+The high VCO is a big more complicated, as the old Low VCO resonator will need to ground with a diamond grinder.  It's .850" long and needs to be .670" long.  Grinding needs to be done from the non-shorted side.  This will remove the center lead, but it's easy to solder a lead on it once it's installed.
-The high VCO is the same, just on the side of the VCO closer to the edge of the main board (bottom).
+Once the grinding is done, install the resonator and fashion a center lead out of some silver plated wire and solder it in place.
-Clean it with some solvent and let it dry.
+Check the Fr on the spectrum analyzer, you want 535 MHz at 6V, it's best to be a bit low (long) with the resonator and then touch up the tuning capacitor with a diamond tip grinder to bring it up the frequency.
-* The case needs to be reinstalled so clean out the holes and set it in place.
+Do a sweep (2-10v) and ensure it covers the intended range for the High VCO (527-543 MHz).  You want the coverage to be in the sweet spot of 2v to 10v, if it's not re-adjust it or grind some off the resonator.  Generally this is not that critical.
-Let the VCO cool and test both sides of the VCO once cooled.
+Clean it with some solvent and let it dry.
 Below is real data from a R1 to R2 conversion.  The before data was taken with the shield off making the frequency about 2 mhz lower.  The pink represents the sweet spot of the VCO tuning voltages.  Note this covers both VCO ranges acceptably.
@@ Line 251: / Line 255: @@
 |-
 |Delta||50||48||46||47
 |}
 === Image filter ===

@@ Line 135: / Line 135: @@
 == R0 to R2 ==
-It's important to have a known good working unit on R1 before starting work.  If it is not working at it's intended frequency, fix it first.
+It's important to have a known good working unit on R0 before starting work.  If it is not working at it's intended frequency, fix it first.
 It would be good to become very familiar with the schematic and service manual before attempting this.
@@ Line 151: / Line 151: @@
 === Converting VCO ===
-IC2200 is a sealed unit containing two VCO's.
+The VCO is consisits of the coaxial resonators and LASER cut tuning caps.  Each is shorted at one end and open at the other forming a high Q inductor.
-Check out the schematic! The Diagram is wrong when it shows the upper and lower VCO!
+First we'll need to remove both coaxial resonators, and move the upper one to the lower position.  This is best done by preheating the board using an under-board preheater at 460f.
-[[File:UHF Receiver Models TRE6281-TRE6282-TRE6283-TRE6284 VCO correction schematic.png|thumb|Reversed VCO's]]
+[[File:Board_Preheater.jpg|thumb|Underboard pre-heater]]
 Once this is done, mask off the area using hole cut in some foil. This is a heat shield for the other parts of the board. Some times you need to use kapton tape to secure the foil in place.
-[[File:UHF RX prepped for desoldering.jpg|thumb|UHF RX prepped for desoldering]]
+Once you have this preheated for a few minutes, use the hot air wand with no tip 15 L/m and 650f on the shield.  Move it in a circular pattern while waiting on it to reflow.
-Once you have this preheated for a few minutes, use the hot air wand with no tip  15 L/m and 650f on the shield.  Move it in a circular pattern while waiting on it to reflow.  A dental pick is a good test for reflow, be aware the solder will not all flow at the same time.
+I find it's easier to remove the lower resonator first, and set it aside. Once this is done, remove the upper resonator and while the board is still warm, apply some flux and reflow it in the lower (U2201) position.
-Now the VCO should be exposed and you can tack on some test wires to it while it cools down.
+While the VCO cools down, attach some teast leads to the following points
-[[File:UHF_RX_VCO_hooked_up_for_mod.png|center|thumb|widths=300px|heights=300px|UHF RX VCO test points]]
+[[File:R0_RX_VCO_modification_points.png|center|thumb|widths=300px|heights=300px|UHF R0 RX VCO test points]]
-Hook up to the VCO as shown, we'll do the Low VCO first.
+Hook up to the VCO as shown, we'll do the Low VCO first since it's got a resonator in it.
-* 8.5 V power to high and low VCO (not at the same time).
+* 10v to power the VCO
 * 0-12 V on the steering line.
 * output loops of wire on the VCO output. These are to be looped around a probe and into a spectrum analyzer to view the output.
@@ Line 187: / Line 182: @@
 * The VCO will be 73.35 MHz higher than the intended receiver frequency
-* '''the sweet spot for the VCO steering voltage is 2.5-7.5 v'''
+* '''the sweet spot for the VCO steering voltage is 2-10 v'''
 * each VCO is designed to cover half the range of the quantar.
 * The Exciter will change VCO's when it hits the range's center frequency +25khz (UHF R2 is MHz) . You can verify this my looking at the steering voltage in the exciter as you change frequencies. A test config file (Codeplug) makes this easy.
@@ Line 433: / Line 428: @@
 Congratulations!
 == R0 to R3/4 ==
 No data on this yet, may be doable VCO will be a problem.