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Message |
    
Bushpilot169
Member
Username: Bushpilot169
Post Number: 73
Registered: 2-2004
| | Posted on Wednesday, January 16, 2008 - 3:14 am: | 
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It's been awhile since i'v posted here, but hear go's
the metal cans that are in a radio, is there a way to identify them ? i know that thay have
numbers on the side,but have no clue as to what thay mean, i also know that some of them have
different color's of paint on them, but i still
have no clue as to what it means.
do's anyone know of a way to tell what thay
are and what frequency thay cover ? the reason
that im asking is that, im trying to find one or
2 or more that will cover the 2meter range.
i know that i could buy them, but that will defeat my purpose,
1) my learning of the parts. and 2) my not putting the good parts that i have to use.
thank's bushpilot169 |
2ir473
Intermediate Member
Username: 2ir473
Post Number: 137
Registered: 7-2002
| | Posted on Wednesday, January 16, 2008 - 10:45 am: |
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I can't answer your specific questions, however, a few things come to mind.
First, what type of radio are you trying to use for 2 meters? It must be a VHF radio to start, and from there, depending on a slew of stuff, you may be able to tune the VCO for 2 meters.
But there are other critical factors, such as IF crystal frequency, etc. that will prevent you from tuning certain radios, to 2 meters.
Secondly, the "metal cans", or "tuning slugs", or "coilforms", have different values and purposes, but essentially produce inductance so as to help tune the circuit. Sometimes using different materials, such as a brass screw, in place of the ferrite core, can tune a circuit beyond the limits specified by thr manufacturer, but this requires a far amount of knowledge & test equipment.
If you can tell us more about your specific need, then perhaps a better answer can be given.
Paul
2IR473
CEF-218/ham #107
CDX8412
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Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 326
Registered: 9-2004
| | Posted on Wednesday, January 16, 2008 - 11:47 am: |
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Sounds like he needs to get a 2 meter radio instead of trying to convert something else,or get a 2 meter transverter I.E.that will take a 10 meter signal and shift it up to 2 meters , they come in a kit form as well as already assembled.I have one for 6 meters that I built years ago from kit form and still works fine using 20 meters as the IF puts out about 10 watts and works fine with my TS140 but my main 6 meter rig is my FT920
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
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Bushpilot169
Member
Username: Bushpilot169
Post Number: 74
Registered: 2-2004
| | Posted on Wednesday, January 16, 2008 - 2:19 pm: |
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the project that i want to build is a 2meter
preamp, so it will have to be broad banded so
that it will cover 144 to 148. yes i know that
there kits that i could buy, but anybody can put
a kit together. |
Bruce
Senior Member
Username: Bruce
Post Number: 4586
Registered: 9-2003
| | Posted on Wednesday, January 16, 2008 - 6:33 pm: |
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Check do a google search for: HAMTRONICS web site they should have the coils
On 6 since 66
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Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 327
Registered: 9-2004
| | Posted on Wednesday, January 16, 2008 - 9:42 pm: |
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Good for you Bush,yes lots of people can put together kits some are easy some are more difficult.I am glad to see that you are designing and building a good preamp.The hard part is in the design the easy part is the building and maybe harder still is locating the parts.Keep us posted on how things go , maybe others will give it a try.
Bob CEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
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Bruce
Senior Member
Username: Bruce
Post Number: 4587
Registered: 9-2003
| | Posted on Thursday, January 17, 2008 - 6:36 am: |
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Don't be fooled ..... many low noise transistors that are very cheap are quite good. Many FETS like the 2n4416, U310 and mpf-102 do quite well at 2 meters and are very cheap.
You should look for NF under 1 db and gain over 10 db but remember you will pay a high price for devices under .5 db NF and you might not even see a change over the ONE BUCK 1 db device.
Remember loses through RF switches can kill the NF since losses are added to that number
a ONE DB LOSS ADDED TO A 1 DB DEVICE IS NOW 2DB NF.
Many older radios are helped by a good preamp Here I use a GASFET with .4 DB NF and 20 DB of gain .....
On 6 since 66
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Captian_radio
Intermediate Member
Username: Captian_radio
Post Number: 329
Registered: 9-2004
| | Posted on Thursday, January 17, 2008 - 11:47 am: |
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Good point Bruce,I have a gasfet preamp and it works very well,low noise.
BobCEF451/VE1CZ
Robert L. Spicer The days of radio are just beginning!
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