Farhan,
R51 and 53 bias is not connected to gates of IRF!
Cheers
Raj
At 20/02/2017, you wrote:
The HF1 is a child of compromise, the Minima isn't.
The Minima has no gain before the narrow filtering, it has a high interecept
mixer, very little IF gain and a distortion audio chain. It uses Si570, a very
low phase noise oscillator as well.
The HF1 is a brute force realization of a low cost general coverage
transceiver. It is as best a job as I could do given that 45 MHz narrow band
filters are not easily available and Si5351 affords three clocks. Here is an
updated circuit diagram of the HF1. Don't build it yet. I havent checked it
fully yet for errors. Many values are missing as well. The neat trick here
is that a two LPFs cover 3.5-7 Mhz and 14-28 Mhz. This is possible as
push-pull configuration doesn't have strong even harmonics.
- fÂ
On Mon, Feb 20, 2017 at 5:24 AM, Joe Rocci
<<mailto:joe@xxxxxxxxxx>joe@xxxxxxxxxx> wrote:
Paul
There's nothing to be gained by filtering the harmonics, since the DBM works
best with square wave LO drive. However, filtering the even order harmonics
could be a good thing. That said, the square wave output of the Si5351 is
pretty good and there shouldn't be much even harmonic content of consequence.
Joe
W3JDR
-------- Original message --------
From: Paul Taylor <<mailto:prt459@xxxxxxxxx>prt459@xxxxxxxxx>
Date: 02/19/2017 6:03 PM (GMT-05:00)
To: <mailto:minima@xxxxxxxxxxxxx>minima@xxxxxxxxxxxxx,
<mailto:adwsail@xxxxxxxxx>adwsail@xxxxxxxxx
Subject: [minima] Re: Ping
I thought Minima begat the HF1, which then became the platform for all
such up-converting transceiver experiments.
Dale, I noticed you used "nano board driving an adafruit Si5351 LO
into a 74AC00 with -11db pad into an SBL-1 mixer" in your Minima
inspired DC receiver. I am using the same combination of Nano and
Adafruit si5351, and an unsure what to do about cleaning up the
harmonics on the square wave output before the SBL-1 mixer. I asked
this question on qrp-tech list a month ago.
Are you using the NAND gates as a squarer, to eliminate harmonics? If
so, did you try conventional LPFs? And clearly you don't mind driving
the SBL-1 with a square wave. What is the highest frequency your
74AC00 works at? Any further things I should know before trying this?
regards Paul VK3HN.
On 18 February 2017 at 22:37, Dale Ward
<<mailto:adwsail@xxxxxxxxx>adwsail@xxxxxxxxx> wrote:
A failure? Imho certainly not. And not because the Minima as designed was a
'wire it up as shown and go' but because of the motivation it provided. I
went with a D.C. Receiver loosely based on W7EL's optimized Transceiver. In
my version I used a nano board driving an adafruit Si5351 LO into a 74AC00
with -11db pad into an SBL-1 mixer. That was followed by a diplexer and LNA
into 2 sections of NE5532 for audio gain into a tiny class D amp to drive a
speaker. Stunning performance and over a years worth of learning to get it
all working. The modular approach with careful 50 ohm matching of each
section made it simple to try countless iterations of oscillator, passive
filters, audio high gain stages, etc. and, at least for me, my deepest
thanks to Farhan for his inspiration.
The only true failure comes from not even trying.
Content-Type: image/png; name="16804998_10154710300287107_1209693538_o.png"
Content-Disposition: attachment;
filename="16804998_10154710300287107_1209693538_o.png"
X-Attachment-Id: f_izdn0g9d0
