Difference between revisions of "UHF Receiver"

From W9CR
Jump to navigation Jump to search
Line 88: Line 88:
  
 
This is changing, I have a better way, [[Quantar UHF RX conversion|old method]].
 
This is changing, I have a better way, [[Quantar UHF RX conversion|old method]].
 +
 +
  
 
== R1 to R2 ==
 
== R1 to R2 ==
 +
 +
This is the conversion we're focused on as there are tons of 403-433 MHz (US Federal) Range 1 units on the market for cheap. 
 +
 +
In general you should have the following to work on this:
 +
 +
* Soldering iron with fine tip (Metcal suggested)
 +
* Hot air station
 +
* Under board heater
 +
* Small tools/tweezers
 +
* Flux, and other small parts for rework
 +
* Quantar backplane extender cables (PCI extender cables cut down to fit)
 +
 +
Almost needed, you really should have it, but can do without:
 +
 +
* Voltmeter
 +
* Service monitor/SINAD meter
 +
* RJ-9 speaker to SINAD meter input cable.
 +
 +
Nice to have:
 +
 +
* Bench DVM
 +
* Bench PSU
 +
* Spectrum Analyzer and probes
 +
 +
 +
=== Procedure Overview ===
 +
 +
In general the VCO (both) need to be moved up in frequency and the image filters from the mixer need to be moved up by changing some chip caps.  The ID resistors of the board must be changed to identify the receiver as Range 2 as well.  Prior procedures required a bunch of manual power supplies, sweeping the circuit, and monitoring with a spectrum analyzer.  This procedure uses the Quantar to control the receiver as it's being worked on using an extender cable.
 +
 +
=== Preparation  ===
 +
 +
First lets prep the setup and get some notes on the receiver before we move it. 
 +
 +
Setup the Quantar and install the extender cables. 
 +
 +
Remove the receiver from it's housing.
 +
 +
Install the board in the holder.
 +
 +
Hook it up to the backplane and program in the Range 1 test codeplug.
 +
 +
Sweep and record the VCO steering voltage on each channel where it locks.  If not using a voltmeter, you can use the measurement screen in RSS to see the steering level.  This is very important as it gives a base line of performance on the receiver before modification. 
 +
 +
 +
Tables Generator
 +
 +
    LaTeX
 +
    HTML
 +
    Text
 +
    Markdown
 +
    MediaWiki
 +
 +
Result (click "Generate" to refresh)
 +
Copy to clipboard
 +
 +
{| class="wikitable" style="text-align:right; vertical-align:bottom;"
 +
|- style="font-weight:bold; text-align:center;"
 +
! style="text-align:left;" |
 +
! colspan="8" | Lower VCO
 +
! colspan="8" style="background-color:#FFF;" | Upper VCO
 +
|- style="font-weight:bold;"
 +
| style="text-align:left;" | Channel
 +
| 1
 +
| 2
 +
| 3
 +
| 4
 +
| 5
 +
| style="background-color:#F4CCCC;" | 6
 +
| style="background-color:#F4CCCC;" | 7
 +
| style="background-color:#F4CCCC;" | 8
 +
| style="background-color:#F4CCCC;" | 9
 +
| style="background-color:#F4CCCC;" | 10
 +
| style="background-color:#F4CCCC;" | 11
 +
| 12
 +
| 13
 +
| 14
 +
| 15
 +
| 16
 +
|- style="font-weight:bold;"
 +
| style="text-align:left;" | R1
 +
| 384.5250
 +
| 388.2250
 +
| 391.9250
 +
| 395.6250
 +
| 399.3250
 +
| style="background-color:#F4CCCC;" | 403.0250
 +
| style="background-color:#F4CCCC;" | 410.5000
 +
| style="background-color:#F4CCCC;" | 417.9750
 +
| style="background-color:#F4CCCC;" | 418.0250
 +
| style="background-color:#F4CCCC;" | 425.5000
 +
| style="background-color:#F4CCCC;" | 432.9750
 +
| 436.8000
 +
| 440.6250
 +
| 444.4500
 +
| 448.2750
 +
| 452.1000
 +
|- style="font-weight:bold;"
 +
| style="text-align:left;" | R2
 +
| 417.9000
 +
| 421.9250
 +
| 425.9500
 +
| 429.9750
 +
| 434.0000
 +
| style="background-color:#F4CCCC;" | 438.0250
 +
| style="background-color:#F4CCCC;" | 446.0000
 +
| style="background-color:#F4CCCC;" | 453.9750
 +
| style="background-color:#F4CCCC;" | 454.0250
 +
| style="background-color:#F4CCCC;" | 462.0000
 +
| style="background-color:#F4CCCC;" | 469.9750
 +
| 474.1250
 +
| 478.2750
 +
| 482.4250
 +
| 486.5750
 +
| 490.7250
 +
|-
 +
| style="text-align:left;" | R1 Shield on
 +
| UNLOCK
 +
| UNLOCK
 +
| 1.813
 +
| 2.504
 +
| 3.248
 +
| style="background-color:#F4CCCC;" | 4.029
 +
| style="background-color:#F4CCCC;" | 5.678
 +
| style="background-color:#F4CCCC;" | 7.379
 +
| style="background-color:#F4CCCC;" | 3.843
 +
| style="background-color:#F4CCCC;" | 5.495
 +
| style="background-color:#F4CCCC;" | 7.204
 +
| 8.089
 +
| 8.982
 +
| UNLOCK
 +
| UNLOCK
 +
| UNLOCK
 +
|-
 +
| style="text-align:left;" | R1 Shield Off
 +
| UNLOCK
 +
| 1.808
 +
| 2.480
 +
| 3.203
 +
| 3.962
 +
| style="background-color:#F4CCCC;" | 4.743
 +
| style="background-color:#F4CCCC;" | 6.376
 +
| style="background-color:#F4CCCC;" | 8.045
 +
| style="background-color:#F4CCCC;" | 4.735
 +
| style="background-color:#F4CCCC;" | 6.395
 +
| style="background-color:#F4CCCC;" | 8.084
 +
| 8.959
 +
| UNLOCK
 +
| UNLOCK
 +
| UNLOCK
 +
| UNLOCK
 +
|-
 +
| style="text-align:left;" | Delta
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
| 0.667
 +
| 0.699
 +
| 0.714
 +
| style="background-color:#F4CCCC;" | 0.714
 +
| style="background-color:#F4CCCC;" | 0.698
 +
| style="background-color:#F4CCCC;" | 0.666
 +
| style="background-color:#F4CCCC;" | 0.892
 +
| style="background-color:#F4CCCC;" | 0.900
 +
| style="background-color:#F4CCCC;" | 0.880
 +
| 0.870
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
|-
 +
| style="text-align:left;" | R1 SINAD
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
| -120.1
 +
| -120.1
 +
| -120.0
 +
| style="background-color:#F4CCCC;" | -120.1
 +
| style="background-color:#F4CCCC;" | -120.1
 +
| style="background-color:#F4CCCC;" | -120.2
 +
| style="background-color:#F4CCCC;" | -120.0
 +
| style="background-color:#F4CCCC;" | -120.0
 +
| style="background-color:#F4CCCC;" | -120.0
 +
| -119.4
 +
| 119.4
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
|-
 +
| style="text-align:left;" | R2 Shield  On
 +
| UNLOCK
 +
| UNLOCK
 +
| 1.328
 +
| 2.056
 +
| 2.876
 +
| style="background-color:#F4CCCC;" | 3.766
 +
| style="background-color:#F4CCCC;" | 5.680
 +
| style="background-color:#F4CCCC;" | 7.727
 +
| style="background-color:#F4CCCC;" | 2.319
 +
| style="background-color:#F4CCCC;" | 4.001
 +
| style="background-color:#F4CCCC;" | 5.890
 +
| 6.920
 +
| 7.968
 +
| 9.027
 +
| UNLOCK
 +
| UNLOCK
 +
|-
 +
| style="text-align:left;" | R2 SINAD
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
|
 +
|
 +
|
 +
| style="background-color:#F4CCCC;" |
 +
| style="background-color:#F4CCCC;" |
 +
| style="background-color:#F4CCCC;" |
 +
| style="background-color:#F4CCCC;" |
 +
| style="background-color:#F4CCCC;" |
 +
| style="background-color:#F4CCCC;" |
 +
|
 +
|
 +
|
 +
| style="text-align:left;" |
 +
| style="text-align:left;" |
 +
|}
 +
 +
 +
  
  

Revision as of 16:14, 8 April 2024

This page covers the Range 1 to Range 4 receivers. The Range 0 is a newer (and easier to modify) design.

Basics

The basic receiver is pictured below. Note the UHF R1-R4 receivers have a preselector that's flush with the front panel and only 3 adjustment. This is a dead give away that you have a UHF R1-R4 from the front. Unfortunately there is not an easy way to identify it further than by part number.

  • UHF RX Front

  • UHF RX Back

  • UHF RX Case

  • UHF RX Internal

The receiver is a high side injection with the 1st Lo operating +73.35 MHz higher than the receiver frequency.

The SCM knows what type of module is inserted by reading voltage divider resistors on the u2600 A/D Converter. Some of these are on ports used for other things, Change Frequency and Lock and then A8 input is used for ID. Note the resistors have the same labels on the UHF boards but on other bands the same parts have different labels. The R2606 and R2607 form a voltage divider feeding the A8 input with the computed voltage in volts.

Range R2449 Chg Freq R2450 Lock SPACE R2606 R2607 A8 Volts
UHF R0 0 3300 5600 3300 1.9
UHF R1 0 0 1200 1200 2.5
UHF R2 0 3300 1200 1200 2.5
UHF R3 3300 0 1200 1200 2.5
UHF R4 3300 3300 1200 1200 2.5
VHF R2413 R2415 R2812 R2814
VHF R1 0 0 2700 1200 1.5
VHF R2 0 3300 2700 1200 1.5
800/900 R2422 R2414 R2816 R2815
900 0 0 1200 4700 4.0
800 0 0 1200 2700 3.5


The service manual excerpt is in PDF and below.

UHF Receiver Models TRE6281-TRE6282-TRE6283-TRE6284 Service Manual Excerpt

In PNG format.

  • Schematic Sheet 1 of 4

  • Schematic Sheet 2 of 4

  • Schematic Sheet 3 of 4

  • Schematic Sheet 4 of 4

Note on the schematic the VCO high and Low are reversed. This seems to be a recurring theme in the Quantar manuals.

Reversed VCO's

As the VCO runs at 73.35 MHz higher than the intended receive frequency the VCO will expect to lock over the following ranges. The ideal spot for the VCO to operate is between 2.5 and 7.5 Volts highlighted in pink below.

Range Lower VCO Upper VCO
Volts 0.8 2.5 5.0 7.5 9.2 0.8 2.5 5.0 7.5 9.2
UHF R1 462 467 479 491 499 478 491 499 506 514
UHF R2 498 511 519 527 536 514 527 535 543 552
UHF R3 528 543 549 555 564 541 555 561 567 575
UHF R4 553 567 574 580 589 568 580 587 593 601

The VCO is much like the VCO in the exciter, a sealed unit with no further diagram available from the factory.

  • UHF R2 RX VCO Case on

  • UHF R2 RX VCO case off

  • UHF R2 VCO Close up

Conversions

Converting the boards

This is changing, I have a better way, old method.


R1 to R2

This is the conversion we're focused on as there are tons of 403-433 MHz (US Federal) Range 1 units on the market for cheap.

In general you should have the following to work on this:

  • Soldering iron with fine tip (Metcal suggested)
  • Hot air station
  • Under board heater
  • Small tools/tweezers
  • Flux, and other small parts for rework
  • Quantar backplane extender cables (PCI extender cables cut down to fit)

Almost needed, you really should have it, but can do without:

  • Voltmeter
  • Service monitor/SINAD meter
  • RJ-9 speaker to SINAD meter input cable.

Nice to have:

  • Bench DVM
  • Bench PSU
  • Spectrum Analyzer and probes


Procedure Overview

In general the VCO (both) need to be moved up in frequency and the image filters from the mixer need to be moved up by changing some chip caps. The ID resistors of the board must be changed to identify the receiver as Range 2 as well. Prior procedures required a bunch of manual power supplies, sweeping the circuit, and monitoring with a spectrum analyzer. This procedure uses the Quantar to control the receiver as it's being worked on using an extender cable.

Preparation

First lets prep the setup and get some notes on the receiver before we move it.

Setup the Quantar and install the extender cables.

Remove the receiver from it's housing.

Install the board in the holder.

Hook it up to the backplane and program in the Range 1 test codeplug.

Sweep and record the VCO steering voltage on each channel where it locks. If not using a voltmeter, you can use the measurement screen in RSS to see the steering level. This is very important as it gives a base line of performance on the receiver before modification.


Tables Generator 

   LaTeX
   HTML
   Text
   Markdown
   MediaWiki

Result (click "Generate" to refresh) Copy to clipboard

Lower VCO Upper VCO
Channel 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
R1 384.5250 388.2250 391.9250 395.6250 399.3250 403.0250 410.5000 417.9750 418.0250 425.5000 432.9750 436.8000 440.6250 444.4500 448.2750 452.1000
R2 417.9000 421.9250 425.9500 429.9750 434.0000 438.0250 446.0000 453.9750 454.0250 462.0000 469.9750 474.1250 478.2750 482.4250 486.5750 490.7250
R1 Shield on UNLOCK UNLOCK 1.813 2.504 3.248 4.029 5.678 7.379 3.843 5.495 7.204 8.089 8.982 UNLOCK UNLOCK UNLOCK
R1 Shield Off UNLOCK 1.808 2.480 3.203 3.962 4.743 6.376 8.045 4.735 6.395 8.084 8.959 UNLOCK UNLOCK UNLOCK UNLOCK
Delta 0.667 0.699 0.714 0.714 0.698 0.666 0.892 0.900 0.880 0.870
R1 SINAD -120.1 -120.1 -120.0 -120.1 -120.1 -120.2 -120.0 -120.0 -120.0 -119.4 119.4
R2 Shield On UNLOCK UNLOCK 1.328 2.056 2.876 3.766 5.680 7.727 2.319 4.001 5.890 6.920 7.968 9.027 UNLOCK UNLOCK
R2 SINAD




R3 to R2

No data on this yet. Should be doable, VCO will be a problem.

R4 to R2

No data on this yet, may be doable VCO will be a problem.

Retrieved from "https://wiki.w9cr.net/index.php?title=UHF_Receiver&oldid=7840"