KitsAndParts.Com Forum

I liked his setup also. It was a lot like mine.
Leonard

Vern wrote:

Kinda old stuff with a 2008 date but what the hey....

Run this amp with -19dbm in and get 0dbm out. Noticed the transistor is warm. Believe I could pinch it with with my fingers without burning my fingers. Is it wise to put a heat sink on it?

Also, was it designed to run indefinitely/continuously? That's what I want to do with it.

I suspect the 'chief in charge' will read this so while I have your attention, a question. Are there spare transistors available for the 5watt HF CW amplifier - 2SC5739's ??

TU for reading.

Vern W9HLY

Hi Vern,
The RF Amp is designed to run hot, but not too hot that it will burn you.
It can run 100 pct duty cycle.
Only have about 8 pieces of 2SC5739 for emergency repairs.
-Diz

what is the max input voltage this circuit will handle for drive?
I am looking for an amp that can give me 5-6 volts of RF (15-20v pk-pk)
That's around a 30dBM output.

Ken
N1KK

another question ...

why use FT-61 material for T1 & T2 .... or is that BN-61-202 ?

KC7NOA wrote:

another question ...why use FT-61 material for T1 & T2 .... or is that BN-61-202 ?

The RF Amp does not use any -61 materials. Only toroid is a FT37-43...must be thinking of a different amp. - Diz

KC7NOA wrote:

says right under the schematic .... thats where i got it from ..

http://kitsandparts.com/linearamp.php

So .. in the PDF T1 material is referred to as BN-61-202 .....

thats being used as a power transformer .... seen on the net it is spec'd as 0.5 to 10Mhz power transformer ---

im just fishing out why the 15M/10M drops off so bad .....
Its the main reason i never posted my mods for using RD06HHF1 and RD16HHF1's to this amp .....

Mike KC7NOA

I just built one of the HF RF amplifier boards. 
http://kitsandparts.com/rfamp1.1.php

I am using this to increase the signal on a N3ZI DDS2 VFO. 
http://www.pongrance.com/ddfc-cc.html

Measurements are with a Fluke PM3092 oscilliscope.  VFO signal is 7.055 Mhz

The output from the N3ZI DDS2 VFO is about 250 mV p-p (0.25 V p-p)

The output from the HF RF amplifier using 12 VDC when connected to the N3ZI DDS VFO with no attenuator restistors is 4.2 V p-p

The output from the HF RF amplifier using 12 VDC when connected to the N3ZI DDS VFO with attenuator restistors R5 = 150 ohm , R6 = 36 ohm and R7 = 150 ohm (6dB attenuation) is 2.1 V p-p

I need to reduce the output signal to around 1.15 V p-p (0.4 rms).

What values of resistor R5, R6 and R7 do I need in the attenuator?

My plans are to use the DDS2 VFO and HF RF amplifier to drive a Spilsbury SBX-11/SBX-11A transceiver.  Any suggestions would be appreciated.

Cheers!
Stuart
VE3SMF
Ottawa, ON Canada.