The AM Forum
June 22, 2024, 01:09:02 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Sherwood Sync mod to 500Khz  (Read 9513 times)
0 Members and 1 Guest are viewing this topic.
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« on: June 26, 2013, 05:25:53 PM »

Has anyone tried moving a Sherwood sync detector to 500 Kcps?  The stock unit won't go that far.

Grant NQ5T
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5047


« Reply #1 on: June 27, 2013, 04:09:31 PM »

hmmmm there was an Amateur QSO switch to let the unit sync in when carriers are not perfectly lined up.

ooops 500KC wow that ain't gonna play well.
Logged

Fred KC4MOP
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8280



WWW
« Reply #2 on: June 27, 2013, 08:10:30 PM »

Well, why not call the company. I received as much pre-sales answers as needed, and when i requested the schematic, it was included with the unit upon delivery. I don't think it would be hard to move it a little from 455 to 500. I agreed not to share the diagram, but anyway, if you would call Sherwood, I think this would be a simple thing.
Logged

Radio Candelstein
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« Reply #3 on: June 27, 2013, 08:39:19 PM »

I don't have a schematic, which would provide the answers.  I did exchange emails with Rob -- but didn't exactly get a clear answer.  Just that "it would take a modification", with a sense that he wasn't too keen to bother with it or freely share the info presuming I'm not the first person who's ever asked.  Well, ok, fine. 

So that's why I asked here.

Anyway, I've given it up for now.  If the fade gets too bad, I'll just switch to a 455 Khz IF receiver or go do something else like read a book  Grin   Somewhere in the seemingly growing stash of projects never completed I have a board and parts for a sync detector using a Sony chip.  Maybe I'll try to find that stuff, tweak it to 500Khz, and see if it works.
Logged
VE3AJM
Member

Offline Offline

Posts: 379



« Reply #4 on: June 28, 2013, 07:06:20 AM »

How about building a 500kc to 455kc converter for the IF output signal from your receiver?

Al VE3AJM
Logged
WQ9E
Member

Offline Offline

Posts: 3285



« Reply #5 on: June 28, 2013, 09:30:34 AM »

Sherwood sells a mixer and a buffer to convert radios without a 455 Khz. IF to work but I am sure, as suggested previously, you could build one easily for less than buying from Sherwood.  A crystal oscillator would be the simplest if you can source a crystal but a properly built L/C oscillator at the required 955 Khz. injection frequency should be plenty stable.
Logged

Rodger WQ9E
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« Reply #6 on: June 28, 2013, 07:06:36 PM »

I finally found my never-used WD8DAS board.  It will be simpler to deal with since it tunes to 500khz, and I can just leave the SE-3 on the 455khz radios and not mess with it.

Reports at the time were that this board with the Sony chip works very well.  And I already have an audio amp module and power supply to build up a standalone unit.  Didn't already have enough to do this weekend Smiley

Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5047


« Reply #7 on: June 30, 2013, 07:45:40 AM »

Hey Grant
What is the audio quality of the WD8DAS sync detector? I would be interested in contacting Steve to purchase his kit. The Sony was very good for eliminating selective fading, but lacked in full hi-fi audio. The IC 2010 was only good down to 100hz in the bass region and I did not test the 2010 I had, for the upper audio freq.
I'm listening to music on shortwave and the stations are awesome for audio on my 390A, but the selective fading distortion really hurts my old ears.
I do not have any hope of funding the over-priced Sherwood unit............even used
Fred
Logged

Fred KC4MOP
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« Reply #8 on: June 30, 2013, 11:21:39 AM »

Hey Grant
What is the audio quality of the WD8DAS sync detector? I would be interested in contacting Steve to purchase his kit. The Sony was very good for eliminating selective fading, but lacked in full hi-fi audio. The IC 2010 was only good down to 100hz in the bass region

According to Steve's website, he discontinued the kits around 2004 because of parts availability.  That will give you some idea how long my board has been sitting in the box waiting for me to get a round TOIT Smiley  Since I've never used it, I can't comment yet on the audio fidelity, but will once I have it playing.

Logged
WZ5Q
Member

Offline Offline

Posts: 109



WWW
« Reply #9 on: July 01, 2013, 09:38:32 AM »

Howdy Y'all,

I had that exact WD8DAS Kit and had retrofitted it to several Receivers.

This was many years back but from what I remember the Audio Fidelity was definitely lacking on the low end under 90cps. This roll off was from the chip as no other modifications would affect this low freq roll off. The High Frequency extension was just fine but the overall "tone" was flat sounding, no richness. Other then the Fidelity problem, it worked as advertised and performed well in adverse conditions.

IMO, Germanium Diodes with the proper timing, filtering, and impedance matching are the best "sounding" out of all the AM Demodulators. When conditions were decent and I wanted Hi-Fi Audio, I would switch to this detector.

Take Care,
Logged

Mike
WZ5Q
From Deep Down in the Dark Dismal Swamps of the Calcasieu
http://www.wz5q.net
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« Reply #10 on: July 01, 2013, 02:05:32 PM »



IMO, Germanium Diodes with the proper timing, filtering, and impedance matching are the best "sounding" out of all the AM Demodulators. When conditions were decent and I wanted Hi-Fi Audio, I would switch to this detector.


Can you explain what you mean by "timing"?
Logged
WZ5Q
Member

Offline Offline

Posts: 109



WWW
« Reply #11 on: July 01, 2013, 03:08:39 PM »

Howdy,

By Timing, I mean the RC Time Constant of the filters that follow the diodes in order to establish the level of Residual RF on the positive peaks, the Slew Rate Distortion on the negative peaks, and the bandwidth of the demodulated signal. This of course has to handshake along with the loading that the entire circuit puts on the diodes. I usually use a Buffer Amp to present a very high impedance to the detector circuit.

Take Care,
Logged

Mike
WZ5Q
From Deep Down in the Dark Dismal Swamps of the Calcasieu
http://www.wz5q.net
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« Reply #12 on: July 04, 2013, 03:18:15 PM »

Just to close out the quest to put an SE-3 on 500KHz ...

Rob has offered to mod my SE-3 so that it is switchable (from a new switch on the rear panel) between a nominal 455 KHz and 500 KHz.  Problem solved, and at a very reasonable cost.  The DAS SAM board with the Sony chipset is already on its way to a new home since I won't need it after all.  And the SE-3 was delivered to Colorado yesterday.

A 51J4 with SSB mods and 4:1 has become my go-to always-on all mode radio, and being able to put the SE-3 on it makes it close to perfect Smiley

Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5047


« Reply #13 on: July 19, 2013, 06:22:22 AM »

Small report:
Grant, NQ5T, made me an offer I couldn't refuse. Thank you OM. He had no need for the WD8DAS sync detector and sent me the PCB. It was already assembled, I connected the cabling needed for power/I.F. in/Audio out.Steve, WD8DAS, is no longer offering this device. The source for the Sony sync chip and Phase shifting module dried up.
I think that is does a little better job eliminating the distortion from selective fading, then my Flex software and SAM. A slight loss of low end, but not as bad as it was when amplifying the audio output from the original Sony 2010. Apparently some frequency shaping done in the audio ckts of the Sony. This PCB is using the original Sony chip and the Phase Shift Network module that was in the radio.
Fred
Logged

Fred KC4MOP
nq5t
Contributing
Member
*
Offline Offline

Posts: 556



« Reply #14 on: July 19, 2013, 10:04:07 AM »

Glad to hear it's working!  I'm still waiting to hear from Rob that my SE-3 modified with dual IF frequencies is ready to ship back.  Think I'll send him him a "tickler" this morning.

Too many projects, and no where near enough time ...
Logged
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5047


« Reply #15 on: July 19, 2013, 12:19:13 PM »

Same here Grant,
The WX is now interfering with the outside work of looking over my ground radial system, that I know I have nicked some wires mowing. And I want to build a helical wound magnetic loop antenna to experiment this Winter on 80-20M. The jungle effect is taking place in Western Pa. You just stand in one place and melt. You don't have to lift a finger to work up a sweat!! 88F and 73% humidity. Just like my wife's country....The Philippines.
There's all of these fires to put out and then there are some money restraints on projects.
Fred
Logged

Fred KC4MOP
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.354 seconds with 19 queries.