[ARC5] Added detail re 1700kc xtal ask

Tue Jun 18 21:11:20 EDT 2024

I built the HBR-14 and 16 in the early 60’s. There was no crystal filter in those. The first IF was high and the second IF used 85 KHz IF transformers from an ARC-5 receiver, which could have adjustable BW by varying the separation between the primary and secondary coils. The 1700 KHz crystal was to down convert the second if to 85 KHz. 73 – Mike 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

908-902-3831

From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of Michael Kana via ARC5
Sent: Tuesday, June 18, 2024 4:41 PM
To: Tom Lee <tomlee at ee.stanford.edu>
Cc: arc5 at mailman.qth.net
Subject: Re: [ARC5] Added detail re 1700kc xtal ask

Hi Tom

I saw Steve’s response and yours and that convinced me to rethink the IF.  I also listen to the Soldersmoke podcast and they also bring up using the more widely available and low cost xtals for determining the IF. I could order a handful and cherry pick the best for the desired bandwidth. 

I already have a couple 9MHz xtal filters also as an option.  This would allow designing to take place a lot sooner than lucking out and finding a “vintage” surplus xtal

Thx 73

Mike

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On Jun 18, 2024, at 3:01 PM, Tom Lee <tomlee at ee.stanford.edu <mailto:tomlee at ee.stanford.edu> > wrote:

 Hi Mike,

You may wish to consider a different IF for which rocks are more readily available (as I was typing this, I saw Steve J's reply pointing out yet another reason for considering a different IF). For instance, there are tons of chroma subcarrier crystals for NTSC and PAL. I see these going for $0.20 in quantities of 10 from Digikey, making it easy to buy a bag from which to find a good set of matched ones. A higher IF would also give you improved image rejection as an additional benefit. Would that be an option at all for you?

--Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 6/18/2024 11:43 AM, Mike Kana wrote:

Hi all
This is for a crystal filter. The RX designs I’m looking at are th HBR Rx or the 6-4 from the 1964 hand book
If the xtal isn’t exactly 1700, a few KC either side would require some VFO trickery. 
Thx
Mike

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