[HBR] Mixer questions and other tech questions..

[DW Holtman]

Hello,

I hope this is a the right group to ask this question.

 I'm in the process of trying to build a SSB converter something like the 
CV-591 and the HC-10. Both of these designs mix the 455KHZ input to 60KHZ 
for the HC-10 and around 20KHZ in the case of the CV-591. I'm going have a 
PD at 455 KHZ.

 This is where my problem is. I have been reading everything I can find 
about a product detector and still really do not understand how it works. I 
understand that the BFO level must be at least 10 times the strength of the 
If signal. What is the difference between a CW detector and a SSB PD except 
for the stronger BFO signal. I have played around putting a stronger BFO 
signal into the CW detector on a R-390a, with limited results. What circuit 
would be very good PD at 455KHZ that I could lay my hands on.

I have a couple of BFO crystals from a Collins 75S-1 that I bought from a 
junker. Shoule I try to go with the two BFO crystals or build a variable BFO 
that would cover around 452 to 458?  Any suggestions for a very good PD 
circuit would help a lot.

Best,
DW Holtman
WB7SSN





. ----- Original Message ----- 
From: "Peter Bertini" <radioconnection at gmail.com>
To: <hbr at mailman.qth.net>
Sent: Tuesday, August 12, 2008 6:53 PM
Subject: [HBR] Mixer questions and other tech questions..


> Hi
>
> I'm undertaking what will be an modified HBR-16 receiver project, and
> right now I am in the gathering parts stage and have probably 90
> percent of the materials needed--inlcuding the coveted Eddystone dial!
> One thing I'd like to try is using balanced mixers for the first and
> second mixer, and for the PD  using 6JH8 tubes.  I'm wondering how
> these tubes will perform on the upper bands, where Ted used the 2nd
> harmonic of the LO to drive the mixer? I have a feeling that these
> tubes aren't suited for this application, and that may limited my RX
> to 30 meters and below. I'm also wondering which injection scheme
> would work best with these tubes using 2nd harmonic LO injection--LO
> injection to the control grid, or balanced LO injection to the
> defector electrodes?
>
> I am also looking for a source for a 1685 kc crystal, since I wish to
> use some salvaged ARC-5 IF transformers for the 1600 and 85kc IF
> stages. Has anyone had sucess using the ARC-5 BC453 BFO coil in one of
> these receivers--I've seen them used in some of the photos on the web
> pages, but I haven't seen any written comments regarding the same.
>
> I've noticed that the IF half-lattice crystal filter Xtals from a
> Heath HR-10 are just about ideal for conversion between a 1600kc first
> IF to 85kc. I'm also wondering if the HR-10 tuning cap wouldn't be a
> good candidate for the HBR receivers?
>
> Sorry for all the questions, but all input will be appreciated.
>
> Pete k1zjh
> ************************************
> Visit the HBR Receiver Web Site with over 100 pictures of receivers and
> construction notes...... via http://www.qsl.net/k5bcq/
> there is also a mirror (faster response)at http://k5bcq.edebris.com/
>
>
> Retrieve reflector archived data via 
> http://mailman.qth.net/mailman/listinfo/hbr
>