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RF Beacon 145Mhz for ARDF Sport

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VictorPS

Member
Hi,

I am going to build some 145Mhz RF beacon (HAM Band), with 1 Watt RF Output, to be use for ARDF Sport, Fox hunt.

I have search the circuit, but I have problem at the RF power output stage, and the PLL.
Reason, the design is using old and obsolete ICS525 PLL chip and 2N4427 RF Transistor .

This 2 IC is hard to get , for the PLL chip, I may can get a SPI control PLL chip, but for transistor, I look for equivalent 2N3386, also is hard to get.

Question:
1. Can I parallel a few small RF Transistor (), to obtain a 1 Watt output?
if yes, how to do it? just simply parallel?

2. Or any RF Power Transistor (1~2W) that you can recommend?

3. I need a freq between 144~145Mhz, any PLL chip that you can suggest?


Thank you,
Victor
 

Sceadwian

Banned
They don't make crystals with that high a frequency, typically a crystal is used to feed a PLL setup as a clock multiplier.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
They don't make crystals with that high a frequency, typically a crystal is used to feed a PLL setup as a clock multiplier.
Only in 'modern' designs, the standard method was to use a 12.xMHz crystal and a chain of multipliers to multiply it by twelve times, 18.xMHz was sometimes uses as well, and multiplied by eight, there were various other combinations as well.
 

Sceadwian

Banned
Ahh, isn't it nice we have all these nifty IC's nowdays Nigel! =)
 
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Sceadwian

Banned
Ick I bet. RC aircraft and vehicle hardware still use individually tuned crystal much of the time, I don't know why they didn't switch over to all synthesized equipment YEARS ago like the rest of the world did.
 

VictorPS

Member
How about the RF transistor?
Can I parallel a few small RF Transistor (like MPSH10 ,CS9018), to obtain a 1 Watt output, or atleast a 0.5Watt output?

or any RF transistor that can do the job in my application that easy to buy?
 

VictorPS

Member
I can't offer a suggestion on replacement of the transistor, but have you looked at any of these? The last link looks especially promising plenty of much more modern alternatives.

A 144MHz ARDF transmitter
2m 1watt Transmitter for ARDF
ARDF: IARU Region II - Equipment
My reference circuit is the Montreal 525 Two Meter Transmitter.

All above design is using obsolete 2N4427 and PLL chip that hard to get in my country (Malaysia) , even digikey, Farnell, RS Component also not carry that part.

I found BLT80 UHF Power Transistor, is this able to replace 2n4427 and give me at least a 0.5W output?
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
My reference circuit is the Montreal 525 Two Meter Transmitter.

All above design is using obsolete 2N4427 and PLL chip that hard to get in my country (Malaysia) , even digikey, Farnell, RS Component also not carry that part.
Unfortunately none of those are the sort of companies who really carry RF power transistors - it tends to be more specialised companies who do.

I found BLT80 UHF Power Transistor, is this able to replace 2n4427 and give me at least a 0.5W output?
Try it and see.
 

twincam44

New Member
You can aquire the BTL50 from RS Components 198-4426 for about £2.50, they are 1 watt output.
I am going to use them for ARDF TX, Still struggling to get the SMD DeviceS ICS525 and we need 5
 

K9WIS

New Member
Have you looked at the MAXIM MAX2606 to replace the 525...its a cheaper soultion...no crystal required..
I am in the process of reworking the montreal fox to use this part..also palnning on using it for model rocket tracking transimitter...
Brian K9WIS...
 

ccurtis

Well-Known Member
The 2N3866 is a good 1W transistor for VHF, UHF. I've never known anyone paralleling discrete transistors in an RF output stage directly, but I have seen individual RF output stages paralleled together. That doesn't necessarily mean it has not been done, however. There are MMIC VHF amp modules available too, from various manufacturers such as http://www.rfparts.com/pdf_docs/57704-68776/68712n.pdf
 
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