| Topic Review (Newest First) |
| Yesterday 06:15 PM | |
| holl_ands |
IF using a very Low Loss Outdoor Balun (i.e. abt 0.5 dB using Philips, PCB or 4:1 Coax Type) then it is likely Better than a 300-ohm Input Preamp, nearly ALL of which are OLD Designs and hence are likely to use OLD Internal Baluns with MORE than 0.5 dB Loss. Preamp "should" be Mast-Mounted, with very short wires connecting to Antenna. NO need for Twin-lead [and associated Loss when Plastic Insulation gets Wet]...just the short pig-tails coming out of a Cylindrical Balun....or short wires connecting 300-ohm Antenna Terminals to 300-ohm Input Preamp....kept at a constant wire-to-wire distance....and NOT twisted. There is NO SITUATION in which Twin-Lead should be used OUTDOORS....it WILL eventually get wet and/or encased in Snow/Ice. And it should always be kept away from other objects, using stand-offs....so it WILL be degraded if run THRU the Walls....esp. if run thru metal or PVC Conduits.... PS: Old Preamps belong in the Circular File....esp if formerly used Outdoors...and even when New, many didn't meet claimed specs: https://imageevent.com/holl_ands/fil...=0&w=1&s=0&z=4 |
| Yesterday 06:00 PM | |
| Gentleman |
Quote:
Originally Posted by ProjectSHO89
View Post
For every 300 ohm input preamp I've ever seen, if you open it up, the first thing you see is a balun.
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| Yesterday 04:24 PM | |
| ProjectSHO89 | For every 300 ohm input preamp I've ever seen, if you open it up, the first thing you see is a balun. |
| Yesterday 12:41 PM | |
| DXING.Bruce |
Hey: Guys. I just found a great place that sells older NOS tv preamps. After reading the above post with respect to using a uhf antenna with 300 ohm output & a preamp with a 300 ohm input to prevent balun losses, this is the perfect model. It has a 300 ohm input & a 75 ohm output. I will be using my old school Channel Master 4221 with the new preamp. I will post results when I get it set up. They also list models with both the input & output with 300 ohm connections for those die hard twin lead users. Also listed are vhf / uhf preamps & much more. I just ordered the Blonder Tongue Galaxy III uhf only preamp. The store catalog # is 5119. Here's the link for the store. https://www.electronicplus.com/conte...ano&subcat=ano |
| 2018-04-19 01:32 PM | |
| holl_ands |
FYI: Updated Ferrite and PCB Balun Loss Summary and Charts: http://www.digitalhome.ca/forum/186-...ml#post3039322 https://imageevent.com/holl_ands/files/ota [Charts towards bottom of webpage] |
| 2018-01-29 09:06 PM | |
| wildwillie |
You guys get this 4:1 coax cable balun figured out yet for VHF hi and UHF My bow tie rat rod is running one lol |
| 2017-05-12 02:09 PM | |
| Zank Frappa |
Both my CM94444's are less than 2 years old and one hasn't ever been used beyond a couple days trying to make the dual ganged ff4 work (too unwieldy). I tried the unused one and it matches the one I've had on for a year and a bit, no difference. I bought the new pair only because The source no longer carries the CM94444's and these Chinese ones looked the same. I guess those CM94444's were a bad batch.] |
| 2017-05-12 01:57 PM | |
| holl_ands |
I measured lots of different Indoor & Outdoor BALUNS....they all had significantly LOWER Loss in FM Band than UHF. In the four BALUN's that ADTech measures (incl CM94444) Loss in Hi-VHF Band was UNDER 0.5 dB. So your old CM94444's have probably been degraded due to Absorbed Moisture and/or Static Electricity Breakdown....or perhaps the oxidization on the coax connectors was disturbed when you first changed Baluns (in which case you might find the CM94444's NOW work the SAME???). |
| 2017-05-12 01:12 PM | |
| Zank Frappa |
I recently ordered 2 very cheap baluns off ebay that I intend to use on a pair of ganged VHF antennas. They looked exactly like my CM94444's that I bought through radio shack/the source. When I got them they were different, it's obvious they are hollow in comparison to the CM94444's which seem solid. I tested both out on my FF4 antenna and they were MUCH better than the CM94444's on VHF with no discernable difference in UHF. Normally CFTO Toronto comes in around 50-60% ss with the CM94444's, these "knockoffs" gave a reading of 86-90%, when I tried pulling in WICU (rf12), which is tropo only for me, I got nothing, not even a "poor signal strength", switched to the cheap Chinese Balun and low and behold it gave me a nice picture at 40%ss, switched back nothing. Since Sunday night I've been getting WICU every night in good quality BEFORE I get WJET (which is my true tropo from Erie), this NEVER happens using the CM94444's, WICU is always the more difficult to get and more often than not unless tropo is really strong out of Erie I don't get it. From what I've read this doesn't make a lot of sense unless CM had a run of bad product and both my others are part of that bad batch. P.S. The Source in Canada no longer carries them, that was why I ordered off flea bay.  P.P.S. I got a pair with weather boots for less than $3 delivered. |
| 2016-05-19 09:08 PM | |
| rabbit73 | Good; thank you. |
| 2016-05-19 08:36 PM | |
| goforit | I got it from Summit Source. I did eventually get the boot off with a lot of tugging... |
| 2016-05-19 08:21 PM | |
| rabbit73 |
Very odd. Who makes that balun? It looks a lot like this one: http://www.vetco.net/catalog/product...roducts_id=826 If it is, the boot has been forced on too far. |
| 2016-05-19 08:08 PM | |
| goforit |
Installing Coax Cable to Balun with Weather Boot I'm trying to connect a coax cable to a balun (see pics), but it has this heavy duty weather boot; not sure how to connect. Slice the weather boot to increase the hole, pull the boot off the balun (tried but doesn't want to come off), or...? Thanks. |
| 2015-12-07 09:03 PM | |
| rabbit73 |
Because when you connect the two halfwave coaxial baluns in parallel they present an impedance of 150 ohms to the feed point of the antenna for a 2:1 SWR mismatch. And then you have two lengths of 75 ohm coax hanging down to connect to the coax feed line. How are you going to do that? Please draw a diagram of what you want to do, so that I understand your plan. Or better yet, why don't you make two baluns and connect them to your antenna and tell us what happens. |
| 2015-12-07 01:06 AM | |
| schoolbus |
Why wouldn't it work? schoolbus |
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