Hello Readers, I have just joined VKLogger following a suggestion when I found that the VK4DD online shop had closed.
With the close down of Analogue TV in New Zealand our club the Auckland VHF Group has received some surplus VHF TV amplifiers containing a device similar to BLF248. These amplifiers use a PCB that is too frequency concious to convert to 144 MHz.
Does anyone know how to purchase the single device VK4DD design for the BLF248? It would allow us to take advantage of the device and metalwork to make a nice PA for 2m. I have had information about the dimensions so know that the PCB will fit the metalwork.
Regards, ZL1UKG
300W BLF278 PA 48V (PA0V Nanko)
-
ZL2WHO
- Frequent Poster
- Posts: 199
- Joined: Mon Dec 28, 2009 6:10 am
- Location: Palmerston North En Zed
- Contact:
Re: 300W BLF278 PA 48V (PA0V Nanko)
Hi Kevin. With the introduction of the LDMOS devices the BLF278 and MRF151G are now to expensive. I have watched ebay and even secondhand devices are about 90 USD and you just dont know if they are going to work. A new 151g/278 can set you back 120 plus USD. These things do produce 300W but its working hard and with a LPF you would only get a comfortable 250w into 50 ohms. These things are hand grenades too, the 151g can only withstand a VSWR of 5:1, I know, iv gone through loads, in saying that the 6m 2WHO beacon uses 2x 151g and a combiner but the key is to have plenty of protection. If the PA did fail then I would not buy the 151g again, id go to a single LDMOS device.
I was lucky enough to buy the BLF174XR 600w devices for about $50NZD each and have just recently constructed a PA for the 88-108 band. With a LPF I get 400w out with ease with under 700 in. The QRO LDMOS are very good $/W.
There are new BLF574 devices on ebay at the mo for $66 USD, these are a 600w device.
but again in china so a little nervous to buy but there is only one way to find out.
Keen to see what you have and what you are intending to make.
Mark.
Update...
The Ebay listing for the BLF574 has been pulled
Reason... "This listing was ended by the seller because there was an error in the listing". It only took them 2 months to realize it was in error. ( If its too good to be true......etc.. )
While this is a pain, LDMOS is still good value as the BLF188XR (1.2Kw) is $ 210 USD so better buying than the 300w devices above.
2WHO.
I was lucky enough to buy the BLF174XR 600w devices for about $50NZD each and have just recently constructed a PA for the 88-108 band. With a LPF I get 400w out with ease with under 700 in. The QRO LDMOS are very good $/W.
There are new BLF574 devices on ebay at the mo for $66 USD, these are a 600w device.
but again in china so a little nervous to buy but there is only one way to find out.Keen to see what you have and what you are intending to make.
Mark.
Update...
The Ebay listing for the BLF574 has been pulled
Reason... "This listing was ended by the seller because there was an error in the listing". It only took them 2 months to realize it was in error. ( If its too good to be true......etc.. )While this is a pain, LDMOS is still good value as the BLF188XR (1.2Kw) is $ 210 USD so better buying than the 300w devices above.
2WHO.