Channel Master 3617 remodel? - Canadian TV, Computing and Home Theatre Forums

 5Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes

post #1 of 16 (permalink) Old 2019-01-25, 05:56 PM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Question Channel Master 3617 remodel?

I have the original specifications for the 3617 and was planning on building a clone.

However since some of the bandwidth it was designed to pick up is no longer utilized for TV transmissions.

I was wondering.

Would it be possible to remodel that antenna so that it is optimized for the repack?
Sev is offline  
Sponsored Links
Advertisement
 
post #2 of 16 (permalink) Old 2019-01-25, 06:26 PM
 
Join Date: Mar 2017
Posts: 31
As far as I can tell, the CM 3617 is a VHF only antenna, and the current use of channels 2-13 hasn't changed much, if any, since the original design.
Neil L is offline  
post #3 of 16 (permalink) Old 2019-01-25, 09:52 PM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
I'm losing my mind.
I dont know what I was thinking.
Thanks Neil.
Sev is offline  
 
post #4 of 16 (permalink) Old 2019-01-27, 05:50 AM
Veteran
 
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,395
Le's try this again. CM3671 "Crossfire" is old Ch2-69 COMBO Antenna, where the smallest elements are for UHF and would be the only ones that MIGHT be changed to improve performance on upcoming Ch14-46 UHF Band:
https://pimages.solidsignal.com/CN3671_zoom.gif

No longer on-line, "cmg2.gif" file provided Gain info for CM3671 [in dBd], ranging from only 9.7 dbi on Ch14 [YUCK!!!] up to 14.7 dBi on Ch52 [after converting to dBi]:
https://photos.imageevent.com/holl_a...20-%20cmg2.jpg
https://photos.imageevent.com/holl_a...0-%20cmg2a.jpg

IF (say) nikiml's Python Optimization Scripts was used to re-Optimize both Element Lengths (Most Longer) AND ALSO Placement on the Beam, then I would Guesstimate that Gain MIGHT be improved by up to about 0.5 to 1.0 dB, based on my results for higher Gain NU-FF6 vs FF6. And if ONLY the Length was re-Optimized on some/most Elements, the improvement would be significantly Less:
https://imageevent.com/holl_ands/mul...6baybowtievdar
https://imageevent.com/holl_ands/mul...orm6bayvdaropt

Note that CM3671 has about a 5 dB lower Gain on Ch14 than Gain on the Higher Channels....which is very typical for Wide-Band Yagi Antennas [incl 91XG]. I doubt that a re-Optimized UHF section would improve on this very much, anticipating that Ch14 MIGHT be 4 dB lower Gain than on Ch36. Compare this to the Frequency response of my NU-FF6 which shows only 2.6 dB lower Gain on Ch14 than Ch36. [Will post "soonish": NU-FF4 shows only 1.0 dB lower Gain.]

So there is only minimal improvement possible in CM3671.....IF the re-Optimization were Accurate....which I DOUBT would be the case using Low-Rez NEC2 Engine, which I predict would have problems with those three much longer "arrow" type Directors [primarily for Hi-VHF, but can NOT be ignored for UHF].....the NEC2 Engine likes all of the Element lengths to be in the SAME frequency band. [Which is one reason why Ken Nist and I usually use somewhat different 4nec models in Hi-VHF and UHF Bands.] So, NO, I am NOT interested in attempting this WHAT-IF exercise.....

If you think that you need higher UHF Gain, I would suggest adding a higher Gain UHF Antenna [perhaps re-Optimized for the New UHF Band] and continue using CM3671 for Ch2-13:
Sev likes this.

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2019-01-27 at 07:05 AM.
holl_ands is offline  
post #5 of 16 (permalink) Old 2019-01-27, 09:17 AM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Thanks Hollands for the input on the 3671.
It Appears largest improvement in gain to that antenna is when the UHF and VHF ends are separated and individual baluns are installed.
If that information is accurate.
I have been planning on doing the same mod on an 8200U I have.


http://hdtvprimer.com/antennas/CM3671mod.gif


I however got my wires crossed on the 3617B Crossfire. It was actually the antenna I was talking about. Just had a brain fart about it being VHF.
What I did get correct is the fact that I have the full specifications for the 3617 from Channel Master.
Let me know if you would like to have them for modeling purposes.
I would be interested in see the antenna's performance is for DX'ing purposes.

I am still searching for the specifications of the quantum 1110 as well.
I believe is was Stampeder, 300 ohm and another gentleman that had very good success in improving gain on that antenna by extending the nose by 2-4 elements and adding floating directors to every set of elements except the rear most.
Sev is offline  
post #6 of 16 (permalink) Old 2019-01-28, 06:48 PM
Veteran
 
Join Date: Nov 2008
Location: San Diego, CA
Posts: 3,395
Due to anticipated modeling problems using NEC2 Engine, I have no interest in knowing dimensions of CM-3617B....

But I remain interested in modeling Winegard Hi-VHF/UHF Combo Antennas [HD7694, HD7697, HD7698, HD8200] if someone were to provide detailed dimensions....and photos with ruler shown in the photo....

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
holl_ands is offline  
post #7 of 16 (permalink) Old 2019-01-29, 10:34 AM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Would this interest you?

[IMG][/IMG]
Sev is offline  
post #8 of 16 (permalink) Old 2019-08-17, 03:36 PM
 
Join Date: Dec 2016
Location: Mississauga
Posts: 49
I got lucky not too long ago when I came across a never used CM-3617, still new in the an unopened box! I got it from a local guy on Kijiji that was cleaning out his garage and found it in the back.. it had a date on it of 1998. Best thing was I paid only $100 for it !!!

I did the Hepburn mods to it, separating the VHF and the UHF and placing a 19dB amp only on the UHF feed at the antenna as seen here: Antenna Project
As William reported " Awesome results. UHF gain much better. VHF improved too, lower noise floor "

And here is my install: http://ads-b.ca/ADS-B_CM3671/

I've had some great DX results with low VHF skip.
First was KNOP RF channel 2 Nebraska at 1742 Km.
That was soon outdone by KHME RF channel 2 Rapid City, South Dakota a new record for me of 1885 Km !

As for Buffalo I can now pick up some of the low power guys too like WBBZ RF7 and WBXZ RF 17.
Sev likes this.
Satellite97 is offline  
post #9 of 16 (permalink) Old 2019-08-20, 06:43 PM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Very nice.
Thanks for sharing.

I see you have some extra mast above the 3671. Any plans for it?
Sev is offline  
post #10 of 16 (permalink) Old 2019-08-20, 06:52 PM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Quote:
Originally Posted by holl_ands View Post
Due to anticipated modeling problems using NEC2 Engine, I have no interest in knowing dimensions of CM-3617B....

But I remain interested in modeling Winegard Hi-VHF/UHF Combo Antennas [HD7694, HD7697, HD7698, HD8200] if someone were to provide detailed dimensions....and photos with ruler shown in the photo....
I will see what I can do on the 8200U for you Hol_lands.

I switched it out with my VHF Archer and a HDB91x. It is just laying on the backside of the roof at the movement.

Also just recently picked up a Quantum 1112 in pretty good shape. Only 1 bad element that would have been fine if the previous owners didnt trip over it after taking it down.
You dont happen to know if the main body of the 1111 and 1112 are the same length per chance?
Sev is offline  
post #11 of 16 (permalink) Old 2019-08-21, 11:20 AM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Quote:
Originally Posted by Satellite97 View Post
I got lucky not too long ago when I came across a never used CM-3617, still new in the an unopened box! I got it from a local guy on Kijiji that was cleaning out his garage and found it in the back.. it had a date on it of 1998. Best thing was I paid only $100 for it !!!

I did the Hepburn mods to it, separating the VHF and the UHF and placing a 19dB amp only on the UHF feed at the antenna as seen here: Antenna Project
As William reported " Awesome results. UHF gain much better. VHF improved too, lower noise floor "

And here is my install: http://ads-b.ca/ADS-B_CM3671/

I've had some great DX results with low VHF skip.
First was KNOP RF channel 2 Nebraska at 1742 Km.
That was soon outdone by KHME RF channel 2 Rapid City, South Dakota a new record for me of 1885 Km !

As for Buffalo I can now pick up some of the low power guys too like WBBZ RF7 and WBXZ RF 17.
I have been planning on attempting the same mod on my 8200U
Sev is offline  
post #12 of 16 (permalink) Old 2019-08-23, 01:18 PM
jop
Rookie
 
Join Date: Jul 2019
Posts: 9
Analyze ofCM-3617B Antenna VHF low-band (54-88 MHz) VHF high-band (174-216 MHz)
reference of document CA781010A.pdf
Capacitor 2.7pF (optional min=1.5pF max=4pF)
MMANA-GAL basic --> Loads 2.7pF in C/jX/BO = 0.27
4nec2--Loads 2.5pF and --> C(Farad)=2.5e-12
Capacitor optional min=1.2pF max=4pF)

graphic dimension usage of in analyze antenna


graphic VHF low-band (54-88 MHz)

graphic VHF high-band (174-193 MHz)

graphic VHF high-band (199-216 MHz)

full document:
CM_3617Bv1

Programs used:
LibreCAD, Open Source 2D-CAD
http://librecad.org/
Open file: Antenna_CM_3617B_v1_inch.dxf

MMANA-GAL basic is freeware an antenna-analyzing tool based on the moment method
http://hamsoft.ca/pages/mmana-gal/mmana-gal---home.php
Open file: CM_3617B_v1.maa
Open file: 55_Mhz_v1.mab in Tools > Compare

4nec2 antenna modeler and optimizer by Arie Voors
http://qsl.net/4nec2/4nec2.zip
Open file: CM3617B_v1.NEC
Sev likes this.
jop is offline  
post #13 of 16 (permalink) Old 2019-08-23, 03:40 PM
jop
Rookie
 
Join Date: Jul 2019
Posts: 9
problems resolved graphic:
graphic dimension usage of in analyze antenna

https://www.digitalhome.ca/forum/alb...ictureid=15447
graphic VHF low-band (54-88 MHz)

https://www.digitalhome.ca/forum/alb...ictureid=15449
graphic VHF high-band (174-193 MHz)

https://www.digitalhome.ca/forum/alb...ictureid=15451
graphic VHF high-band (199-216 MHz)

https://www.digitalhome.ca/forum/alb...ictureid=15453
Sev likes this.
jop is offline  
post #14 of 16 (permalink) Old 2019-08-31, 01:13 PM Thread Starter
Sev
 
Join Date: Feb 2018
Posts: 65
Very Nice.
Thank you Jop
Sev is offline  
post #15 of 16 (permalink) Old 2019-08-31, 01:39 PM
 
Join Date: Aug 2009
Location: Dallas, TX
Posts: 77
Thank you, jop.

Nice work on original 3617 & 3617B.

Also, appreciate the files on Antenna Direct's; DB4e & DB8e.

There are likely some things in files that will be helpful, or good examples to emulate for other antenna modeling applications.

Again, thank you for your effort and for providing the files related to your results.

.
Sev likes this.
tripelo is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Canadian TV, Computing and Home Theatre Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome