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6_metre_conversion_prm80 [2018/09/14 22:24]
vk3smb [Alignment] 		6_metre_conversion_prm80 [2018/09/14 22:36]
vk3smb [Alternative to changing the reference oscillator]
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 ===== Specifications I ended up with. ===== ===== Specifications I ended up with. =====
  
- +^ Frequency ^ Rx sens (12db sinad) ^ TX power ^ TX current ^ 
-Frequency +|48Mhz|1.173uV|Nil VCO lock|Nil VCO lock| 
-  +|49Mhz|0.268uV|19.6W|4.28A| 
- +|50Mhz|0.252uV|21.7W|4.58A| 
-Rx sens (12db sinad) +|51Mhz|0.241uV|23.5W|4.87A| 
-  +|52Mhz|0.241uV|24.7W|5.11A| 
- +|53Mhz|0.239uV|25.3W|5.22A| 
-TX power +|54Mhz|0.241uV|25.1W|5.23A| 
-  +|55Mhz|0.271uV|24.5W|5.08A| 
- +|56Mhz|0.436uV|Nil VCO lock|Nil VCO lock| 
-TX current +|57Mhz|0.456uV|Nil VCO lock|Nil VCO lock| 
- +|58Mhz|0.472uV|Nil VCO lock|Nil VCO lock| 
-48Mhz +|59Mhz|0.492uV|Nil VCO lock|Nil VCO lock| 
-  +|60Mhz|0.518uV|Nil VCO lock|Nil VCO lock|
- +
-1.173uV +
-  +
- +
-Nil VCO lock +
-  +
- +
-Nil VCO lock +
- +
-49Mhz +
-  +
- +
-0.268uV +
-  +
- +
-19.6W +
-  +
- +
-4.28A +
- +
-50Mhz +
-  +
- +
-0.252uV +
-  +
- +
-21.7W +
-  +
- +
-4.58A +
- +
-51Mhz +
-  +
- +
-0.241uV +
-  +
- +
-23.5W +
-  +
- +
-4.87A +
- +
-52Mhz +
-  +
- +
-0.241uV +
-  +
- +
-24.7W +
-  +
- +
-5.11A +
- +
-53Mhz +
-  +
- +
-0.239uV +
-  +
- +
-25.3W +
-  +
- +
-5.22A +
- +
-54Mhz +
-  +
- +
-0.241uV +
-  +
- +
-25.1W +
-  +
- +
-5.23A +
- +
-55Mhz +
-  +
- +
-0.271uV +
-  +
- +
-24.5W +
-  +
- +
-5.08A +
- +
-56Mhz +
-  +
- +
-0.436uV +
-  +
- +
-Nil VCO lock +
-  +
- +
-Nil VCO lock +
- +
-57Mhz +
-  +
- +
-0.456uV +
-  +
- +
-Nil VCO lock +
-  +
- +
-Nil VCO lock +
- +
-58Mhz +
-  +
- +
-0.472uV +
-  +
- +
-Nil VCO lock +
-  +
- +
-Nil VCO lock +
- +
-59Mhz +
-  +
- +
-0.492uV +
-  +
- +
-Nil VCO lock +
-  +
- +
-Nil VCO lock +
- +
-60Mhz +
-  +
- +
-0.518uV +
-  +
- +
-Nil VCO lock +
-  +
- +
-Nil VCO lock+
  
 Please note these were measured 25khz up from the frequency as microprocessor noise was evident. Please note these were measured 25khz up from the frequency as microprocessor noise was evident.
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 Four of these radios have been built, one by Phil, the others by myself, we both did it with parts from the Junk Box, with the exception of the crystal (I had nearly every value but 8Mhz). Each of the modified radios ended up with similar specifications. These measurements were taken with a Marconi 2955 service monitor. Four of these radios have been built, one by Phil, the others by myself, we both did it with parts from the Junk Box, with the exception of the crystal (I had nearly every value but 8Mhz). Each of the modified radios ended up with similar specifications. These measurements were taken with a Marconi 2955 service monitor.
  
-Â Â+{{:20062010016.jpg?direct&200 |}}{{ :20062010017.jpg?direct&200 |}}
 Photo's of the service monitor with one of the "production" units on test. Photo's of the service monitor with one of the "production" units on test.
  
  
-Errors and Headaches during the R & D Phase+===== Errors and Headaches during the R & D Phase ===== 
 Many hours of playing has gone into this, particularly trying to work out how to break the magical 58Mhz barrier. Many hours of playing has gone into this, particularly trying to work out how to break the magical 58Mhz barrier.
  
-    I went to de-compile the firmware in the pmr8030, after seeing the output, I forgot that idea straight away. +  *     I went to de-compile the firmware in the pmr8030, after seeing the output, I forgot that idea straight away. 
-    I thought about putting a frequency tripler between the pll and the pre-scaler and programming the radio to 156Mhz odd. This was shot down in flames with the availability of something small enough to fit in the radio shield and stability was also going to be an issue. +  *     I thought about putting a frequency tripler between the pll and the pre-scaler and programming the radio to 156Mhz odd. This was shot down in flames with the availability of something small enough to fit in the radio shield and stability was also going to be an issue. 
-    I found some 40/41 pre-scalers. This worked ok at 52Mhz, but due to rounding errors in my mathematics, I was out 80Khz at 54Mhz. And the steps were quite an odd value. But with Phil clearing the forest so I could see the trees, I found a simple crystal change would have saved me a heap of work. +  *     I found some 40/41 pre-scalers. This worked ok at 52Mhz, but due to rounding errors in my mathematics, I was out 80Khz at 54Mhz. And the steps were quite an odd value. But with Phil clearing the forest so I could see the trees, I found a simple crystal change would have saved me a heap of work. 
-    After spending around 6 hours rebuilding the RX front end, changing caps etc, I found I didn't need to do all that, all I had to do was change the slugs from brass to ferrite. +  *     After spending around 6 hours rebuilding the RX front end, changing caps etc, I found I didn't need to do all that, all I had to do was change the slugs from brass to ferrite. 
-    During TX playing, I've managed to damage 2 PA's as the driver has a staggering amount of gain at 50Mhz. +  *     During TX playing, I've managed to damage 2 PA's as the driver has a staggering amount of gain at 50Mhz. 
-    After a lot of hair pulling, found out the stripline between the driver and PA is too short, causing it run away when the case was re-assembled due to a mis-match and extra capacitance of the shield.+  *     After a lot of hair pulling, found out the stripline between the driver and PA is too short, causing it run away when the case was re-assembled due to a mis-match and extra capacitance of the shield. 
 + 
 +===== Problems =====
  
-Problems 
 If anyone can think of answers to these I'd love to know them. If anyone can think of answers to these I'd love to know them.
  
-    The repeater defeat button will not work as the IF offset is different due to the "hacked" programming. If the VCO did lock it would be transmitting above 60Mhz for frequencies programmed in for 53Mhz +   *    The repeater defeat button will not work as the IF offset is different due to the "hacked" programming. If the VCO did lock it would be transmitting above 60Mhz for frequencies programmed in for 53Mhz 
-    Microprocessor noise is evident at quite a few places on the band.+  *     Microprocessor noise is evident at quite a few places on the band.
  
  
-Thanks to+===== Thanks to ===== 
 Jason, VK7ZJA for his excellent and thorough documentation on the Prm80, and for exhausting every other avenue before I got to them. Jason, VK7ZJA for his excellent and thorough documentation on the Prm80, and for exhausting every other avenue before I got to them.
 Phil, VK3ELV for his ideas and the re-development of the PA Phil, VK3ELV for his ideas and the re-development of the PA
 Garry, VK3XYX for his donation of "rubbish" E band RF boards, and Garry, VK3XYX for his donation of "rubbish" E band RF boards, and
-My better half Jess for letting me play in the shack a little longer than usual.+
  
 Have Fun Have Fun
  
-Alternative to changing the reference oscillator+===== Alternative to changing the reference oscillator ===== 
 I have finally worked out the Firmware in the PRM8025/30's for a neater conversion, follow the following link to do a firmware upgrade and benefit from less processor noise and "normal" radio behaviour. I have finally worked out the Firmware in the PRM8025/30's for a neater conversion, follow the following link to do a firmware upgrade and benefit from less processor noise and "normal" radio behaviour.
-Firmware information page+[[prm80_firmware|Firmware information page]] 
 + 
 +===== Disclaimer =====
  
-Disclaimer 
 While all information in this document has been tested by myself, I offer no liability for any damage caused by using the information within. This Document is Copyright and remains the property of Matt Bilston, VK3VS. I give my permission for this document to be published in Amateur Radio, and the similar publications in NZ, UK and USA so long as the original content is not modified in any way other than formatting for the magazine. Remember to identify the case in some way that it has been converted to 6M should the radio end up in commercial hands again. While all information in this document has been tested by myself, I offer no liability for any damage caused by using the information within. This Document is Copyright and remains the property of Matt Bilston, VK3VS. I give my permission for this document to be published in Amateur Radio, and the similar publications in NZ, UK and USA so long as the original content is not modified in any way other than formatting for the magazine. Remember to identify the case in some way that it has been converted to 6M should the radio end up in commercial hands again.
  
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 The leftover bits The leftover bits
  
 +{{ :photo13.jpg?direct&400 |}}
 +===== Obtaining parts =====
  
-Obtaining parts 
 It looks like Dick Smith no longer stock the ferrite slugs required. I am going to try and get a source of them. If I can they will be available from me. It looks like Dick Smith no longer stock the ferrite slugs required. I am going to try and get a source of them. If I can they will be available from me.
  
-Looking at junk boxes, Appropriate slugs can be found in E band FM900's!!!!!+**Looking at junk boxes, Appropriate slugs can be found in E band FM900's!!!!!**
  
 Thanks to Dion VK7DB, There is another source of Slugs. He informs me that the old Plessey "Bug Eye" Radios have slugs of the correct thread, pitch and material in them. Thanks to Dion VK7DB, There is another source of Slugs. He informs me that the old Plessey "Bug Eye" Radios have slugs of the correct thread, pitch and material in them.
6_metre_conversion_prm80.txt · Last modified: 2018/09/14 22:37 by vk3smb

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