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ChrisL

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Posts posted by ChrisL

  1. Lowering SWR on Comet Original CA-712EFC 460-470Mhz

    in Technical Discussion

    Posted

    You are already in pretty good shape. Dropping below 1.5, even to 1.0 won't make a substantial increase in performance. It's not nearly as noticeable as, say, going from 2.0 down to 1.5. But, if you want to try for some small improvements...

     

    In general, I don't think you can have too much ground plane. (And I am sure someone here will correct me if that is wrong.)

    So, I'd extend the ground radials as much as possible and see if that makes any difference.

     

    Also, you don't mention it... but, are there any other vertical metal poles or other antennas anywhere close by? Other objects might affect your transmission and SWR.

    Thanks again for your help. There is a house next to the granny house this is mounted on about ten feet away and it's roof is slightly taller than the roof the antenna is attached. There aren't any metal poles nearby but there is an orange tree.

     Speaking of ground plane radials. I was wondering if simply turning the antenna to change the direction the radials are pointed could change the swr? I wouldn't even need to take down the antenna to turn it by a few degrees.

  2. Lowering SWR on Comet Original CA-712EFC 460-470Mhz

    in Technical Discussion

    Posted

    What is the antenna mounted on? Metal pole? Fiberglass? PVC? All of these can affect SWR from my experience. Switching from fiberglass to a 6 foot metal fence post lowered SWR from 1.7 to 1.08. Another thing that affects the SWR reading is the length of feedline. I was told to make sure you measure SWR at one and a half wavelengths, which if I recall is 18 inches from the radio. Many people overlook that and get crazy readings which cause them to panic.

     

    Overall a 1.5 is reasonable (anything 1.5 or less is near perfect) I've run radios as high as 1.7 with little issue. I wouldn't run anything over 2.0 though.

    Thanks for the response. The antenna is mounted on two sections of top rail (metal) and the coax goes into the shack through a pass through in the wall. I'm using a one foot jumper made of LMR-240.

  3. Lowering SWR on Comet Original CA-712EFC 460-470Mhz

    in Technical Discussion

    Posted

    Hi all,

     Got my antenna up and running after about 20 hours worth of work (not including Home Depot trips).

     First I want to mention the performance was better than I had hoped for. Very happy with that. Yesterday had a long chat on a repeater that I wasn't even expecting to hit.

     The second thing Is the the SWR was 1.5 on Medium power from my BTECH 50x1 and and 1.3 on low power. I would like to improve on this.

     I'm using 33ft. of  Times MicroLMR-400 coax with Amphenol PL-259 and Time Micro N-male connector. The #4awg ground rod wire is about 4ft long. The antenna is about 5 ft. over the top of the roof line. I'm using a Diamond 400 SWR meter.

     The instructions said to use either 1 or 2 loops for the rf choke. I made one loop. The radials have a VERY small adjustment of about 1/4" on all 3. I set the radials in as far as they would go and tightened things up. So I could extend them a bit.

     Would adding another loop to the rf choke help and would lengthening the 3 radial make a difference?

     Any advice would help.

     I forgot to mention that I tested the SWR on all the GMRS and GMRS repeater frequencies and they where all very close in measurement.

     Thanks guys for all your help.

     Chris

  6. Waterprofroofing a two piece antenna.

    in Technical Discussion

    Posted

     I would like some advice for sealing a Comet CA-712EFC antenna where the top and bottom come together In the middle. The manual mentions sealing this area for a permanent installation but there is no sealant or tape mentioned in the parts list. I have seen a few ideas online about this topic but it wasn't easy to find and nothing that made me feel confident about the advice. I simply want the center of the antenna to be waterproof and I don't want to do anything that will compromise the SWR measurement.

     I ordered from the Antenna Farm for just about $160 and am excited about the project.

     Thanks for all your advise and yes I did search the forums here and couldn't find an answer.

     Take care,

     Chris

     

  7. Power vs. quality for Tx.

    in Technical Discussion

    Posted

     Once again, thanks for all the well thought out reply's.  The reason for the radios is for emergency purpose. I want to run as low of power as possible to save energy in a power outage. I have quality agm batteries to keep things going and solar. I am barely able to get into 2 different repeaters on 5 watts with my BTECH but my signal is nearly full quiet with the BTECH at the 15 watt setting. I'm using a diamond 400 meter and needle barely moves when I check the SWR (far below 1.5).

     My understanding with the Kenwood 880 and the 880H is that the 880 is 5 watts on low and the 880H is 10 watts on low. So, I wondered if the Kenwood's 880H signal at 10 watts is cleaner than the BTECH's so it may sound as good or better than the BTECH running 15 watts.

    Most of the reply's seem to refer to the antenna and I believe all of you that it would make all the difference in the world to improve on but at the moment I can't. I do however want a second radio that is repeater capable so I figured I may as well get some advice.

     Something I do like about the BTECH 50x1 that I would lose using the Kenwood is the ability to monitor VHF and having an FM radio. Probably considered gimmicky but I do like the features, (at least it doesn't have a flashlight).

     One more thing, the Kenwood's do have CTCSS correct, since that is what our local repeaters use near me.

     

     Thanks

  9. Power vs. quality for Tx.

    in Technical Discussion

    Posted

     I finally got my BTECH 50x1 to work at 15 watts on two different repeaters fairly well. At 5 watts It works but has alot of noise in the signal. I cannot improve my antenna situation any more than I already have due to HOA restrictions otherwise I wouldn't be posting this. I'm considering the Kenwood TK-880h but it may only have a 10 watt low power setting. I want to keep the TX power as low as possible.

     Here's my question, will the better quality Kenwood sound as good or better at 10 watts than my CCR - BTECH at 15 watts when I transmit?

     I just don't want to invest a lot of time (programming learning curve) and a bit of hard earned cash and find out that 10 watts isn't enough.

     Thanks in advance for your help in this matter.

  11. GMRS-50X1 Features Review

    in Equipment Reviews

    Posted

    The radio will scan through the tone codes and digital codes while receiving, to find a match.  The digital code scan is almost instant, but the TSQL is a bit slower.  Once you put it in DPL scan mode, it will continue to scan until the correct squelch is found.  However, unless someone is transmitting for 15 to 20 seconds straight, TSQL may take a couple of transmissions before the tone is found.  In my opinion, less than 30 seconds isn't bad.

     

    Yes, you can run split DPL methods on transmit and receive.

    Mr. Spaz,

     I went ahead and purchased the 50x1 mainly because of the ctcss scanning ability but I am not able to get it to scan. I reread your post and looked at Miklors site prior to writing this to see if there is any kind of instruction but I haven't found anything. I tried researching BTECH 50x2 radio since they are similar but was unsuccessful at finding an answer or video tutorial.

     Supposedly when it scans a "ct"  will appear on the screen but have not been able to make it happen. Hope I made sense.

     Thanks for your time.

     Chris

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