EMRFD Message Archive 8089
Message Date From Subject 8089 2013-01-12 14:47:49 Ashhar Farhan vhf power chain
level. i have 2N5179s and 2N918s in the junk box. what is a stable and
reproducable design? i know of several in the HF range, my initial
attempts at reusing the same HF circuits (10 db feedback amps, three
of them) is not working well, i am hardly getting 6db gain per stage :
i have used 1K feedback between the collector and base, 10 ohms on
the emitter degeneration, a 1:4 bifilar winding on the collector
output with 2N918s.
any ideas?
- farhan8090 2013-01-12 15:44:13 Lasse Moell Re: vhf power chain
Do the transformer work OK at the VHF range?
0,5 watt isn't that a bit high for 2n918/5179??
There are some designs in the Test equipment chapter in Solidstate
Design book, especially fig 12 and 13.
/Lasse SM5GLC
On 12 jan 2013 19:36 "Ashhar Farhan" <farhanbox@gmail.com> wrote:
>
>
> i have to build a vhf power chain taking a -7dbm signal to a half-watt
> level. i have 2N5179s and 2N918s in the junk box. what is a stable and
> reproducable design? i know of several in the HF range, my initial
> attempts at reusing the same HF circuits (10 db feedback amps, three
> of them) is not working well, i am hardly getting 6db gain per stage :
> i have used 1K feedback between the collector and base, 10 ohms on
> the emitter degeneration, a 1:4 bifilar winding on the collector
> output with 2N918s.
>
> any ideas?
>
> - farhan
>
>8091 2013-01-12 15:53:57 kb1gmx Re: vhf power chain 8095 2013-01-12 21:28:37 Jerry Haigwood Re: vhf power chain
You might look at using 2N3866s or 2N3553s or 2N4427s or 2N5109s for
power amps. All are available from:
<http://www.Futurlec.com>
Jerry W5JH
"building something without experimenting is just solder practice"
8096 2013-01-12 21:28:38 Ashhar Farhan Re: vhf power chain
Yes I plan using 2N3866 as the 'final'. The transformers are wound on
FT23-43, five turns. The gain seems to be unusually low. I am going to
recheck the build again.
- farhan