Dualities

[WROA675]

Hello y'all,

  Looking to the not so distant future, as I have my amateur tech license test in December, and wanting dual-purpose antenna idea(s). Being active in my local GMRS community I plan on continuing open communication on that platform, as well as engaging the amateur's radio world.

  I'm seeking your insight because I know there are plenty of folks here that have both their GMRS and HAM licenses, and probably dual base stations. Currently I have the Larsen BSA 450 antenna for my DB25G (as some of you know and assisted in helping me get setup). What kind of dual setups do y'all have?

  Because the Larsen BSA450 isn't a dual band antenna, I'm wondering if setting up another, separate antenna, for HF is better, or would something like the Harvest X50C2 be a good option for me, being able to tx/rx for both systems using just the one antenna (if that's even possible)?

[tweiss3]

Are you looking for base station antenna or mobile?

Mobile: Larsen 2/70SH works well in both ham 2m&70cm as well as GMRS, of course being slightly out of band for GMRS, but quite workable. Larsen 150/450/758 works well in ham 2m&70cm as well as GMRS, but is better for GMRS, and a bit out of band for the ham stuff. I have both, but use the 2/70SH since I talk more on ham than GMRS. 

Base: I have a Tram two piece on my roof designed for ham. Once again, you will have to choose a compromise of one service over the other. It works well for GMRS, though it's not listed for GMRS.

 

Typically, when you go HF or VHF low band (6m), you use an entirely separate antenna than your UHF/VHF antenna. 

[WROA675]

8 minutes ago, tweiss3 said:

Are you looking for base station antenna or mobile?

Thank you, tweiss3, I should have clarified in my post...I'm looking for a base antenna. Where can I research the Tram 2piece, is there a model number?

BTW, I'm in a condo complex and trying to stay low-key and under the radar of the HOA.

[tweiss3]

Mine is the Tram 1480, it is 8' tall. The 1481 is a 3 piece at 17' tall. 

 

I'm, not sure what you have for your current setup, but if you are looking for attic placement, you could likely find a dual band antenna in the 6' tall area, or utilize a mobile antenna on a NMO mount.

[WROA675]

21 minutes ago, tweiss3 said:

Mine is the Tram 1480, it is 8' tall. The 1481 is a 3 piece at 17' tall.

I found a TRAM 1480 with is listed at 6ft (does that sound right? I have a spot and access to my roof (a/c unit deck), where my Larsen is now (3' ish). 

The rafters is a option, if necessary, but the roof, I believe, would give optimum range and performance...please correct me if I'm wrong.

I will do some research on the attic option and more stealth ideas .

[tweiss3]

AntennaFarm lists the 1480 at 8'4", which seems about right.

 

If you are working with 3' right now, you could use the Larsen 2/70 (not SH) https://www.theantennafarm.com/catalog/index.php?main_page=product_info&cPath=191_192_200_450_453&products_id=1712 and put it on a mobile to base adapter (https://www.theantennafarm.com/catalog/index.php?main_page=product_info&cPath=1289_1243&products_id=1649). On the plus, it would be a small black whip and very difficult to see.

[wayoverthere]

14 hours ago, tweiss3 said:

. On the plus, it would be a small black whip and very difficult to see.

Will second this take. When I put close to 3ft of 5/8 over 5/8 wave on my truck I figured it'd be easy to see from a distance, but not so much, it gets lost in the background unless you're right there.

My current base setup is indoors, 5/8 wave whip mag mounted on sheet metal and a btech for gmrs, with a comet gp1 and a dual band icom for 2m/70cm...was hoping to run gmrs on that too with (separate 70cm/gmrs and 2m radios), but swr was too high on gmrs ( 2.5-3:1 ) on the comet. Uhf radio went to the truck for 70cm/gmrs instead, with that browning on a mag mount.  while mounting outdoors will definitely help, especially simplex, both work fine for repeater work, multiple machines within ~30 miles on mid power on 2m and 70cm, and 30 and 60 miles out on high on gmrs

[WROA675]

Follow up question. Moving away from the antenna(s) to the transceiver(s). 

Is there a minimum distance I should have the two units (gmrs and ham radios) from each other? Are there any interference issues I need to be concerned about?

In the picture, you can see my DB25G and I'm wondering if it would be okay to mount my ham unit (hanging in the same fashion) next to it or maybe further to the left (above the books) where the two units would be separated by the partition?

 

[BoxCar]

As long as the two are no transmitting at the same time you are OK. Desense is primarily passed through the antenna into the receiver so it's the antennas that are the key players.

[WROA675]

42 minutes ago, BoxCar said:

As long as the two are no transmitting at the same time you are OK. Desense is primarily passed through the antenna into the receiver so it's the antennas that are the key players.

Copy that...the antennas will be about 15 feet apart, hopefully that's enough distant apart.

[n4gix]

I have had six transceivers stacked on top of one another for close to eight years now. My only problem is remembering which mike goes to a specific radio! 

[WROA675]

Okay, let's move on to power supply...

two mobile radio in my shack (DB25-G-13.8V dc voltage, and K- 8900R-13.8 V dc voltage) . Both have the lighter plug setup, however, the connectors in the middle can be detached.

Is there a power supply unit I can use instead of having two different ac adapters?

Edited November 6, 2021 by Papatree
more info

[BoxCar]

I would look online for a cable that matches the white connector and has the other end of the adapter cable either bare or terminated with fork or round lugs. you can then use a larger supply like https://www.amazon.com/eTopxizu-Universal-Regulated-Switching-Computer/dp/B00D7CWSCG/ref=sr_1_3?crid=ZSAO9DWX9EIZ&keywords=12v+power+supply+30a&qid=1636219326&sprefix=12v+power+supply%2Caps%2C118&sr=8-3 to power both radios.

[axorlov]

It's Kenwood-Yaesu-Icom T connector:

https://www.amazon.com/Qiilu-Connectors-FT-7800R-FT-8800R-FT-8900R/dp/B08FCL69QZ/ref=sr_1_3?keywords=radio+t+connector&qid=1636219982&sr=8-3

Or with the cable and fuses:

https://www.amazon.com/EmBest-Fused-Compatible-Kenwood-Mobile/dp/B00CR00CWM/ref=psdc_597260_t4_B08FCL69QZ

 

[WyoJoe]

On 11/4/2021 at 12:55 PM, n4gix said:

I have had six transceivers stacked on top of one another for close to eight years now. My only problem is remembering which mike goes to a specific radio! 

I have the same trouble with only two or three receivers. Keeping track of 6 microphones would be quite a task!

[wayoverthere]

1 hour ago, WyoJoe said:

I have the same trouble with only two or three receivers. Keeping track of 6 microphones would be quite a task!

I was pondering this last night as I trolled the auction site. Already have a vertex vx4207 for 70cm and gmrs, and found a vx4204 (the vhf version of the same radio) for a tempting price...they're pretty much twins, down to the same mics.

What stopped me from pulling the trigger is a, lack of space in the truck, b, no huge need for vhf, as nearly everything around me on vhf has a linked UHF side, and c, it wasn't a huge gap price wise compared to just grabbing another dual bander.

[WyoJoe]

1 hour ago, Papatree said:

Okay, let's move on to power supply...

two mobile radio in my shack (DB25-G and K- 8900R). Both have the lighter plug setup, however, the connectors in the middle can be detached.

Is there a power supply unit I can use instead of having two different ac adapters?

I use a Tekpower TP50SW, and run the output to a fused distribution block with 8 Anderson Power Pole outputs. The link is to the first similar item I found on Amazon but is not the specific one I'm using.

I then put Anderson Power Pole connectors on the power leads for my radios, and can plug them all into the distribution block. I use a similar setup when running off a battery.

My power supply does have one 12V "lighter" plug, which my Anytone AT-779 is plugged into at the moment. I haven't put the Anderson connectors on it yet.

[wayoverthere]

2 hours ago, axorlov said:

It's Kenwood-Yaesu-Icom T connector:

https://www.amazon.com/Qiilu-Connectors-FT-7800R-FT-8800R-FT-8900R/dp/B08FCL69QZ/ref=sr_1_3?keywords=radio+t+connector&qid=1636219982&sr=8-3

Or with the cable and fuses:

https://www.amazon.com/EmBest-Fused-Compatible-Kenwood-Mobile/dp/B00CR00CWM/ref=psdc_597260_t4_B08FCL69QZ

 

So...for the price, I'd sooner pay a few bucks more and buy better. I've tried a couple times getting the premade wiring with the connector from Amazon, and it was like a wish dot com version of the connector...the dimensions were too off for it to even connect. If you look on the "replacement parts" list for some of the popular radios that use the same connector on dxengineering, they have the "connector to battery" section available separately.  Here's one for the yaesu ft-2980r: https://www.dxengineering.com/parts/ysu-t90258252

Or troll the whole section: https://www.dxengineering.com/search/part-type/dc-power-cable-assemblies?GroupBy=SKU&SortBy=Default&SortOrder=Ascending

[n4gix]

A double (or triple) adapter would be the quickest:

Amazon.com: [Upgraded Version] Electop 1 to 2 Car Cigarette Lighter Splitter Adapter Power Charger Port, 12V 24V Plug Socket 2-Way Splitter Y Adapter, 10 inch Cigarette Lighter Extension Cord 16AWG with 15A Fuse : Automotive

[wayoverthere]

If I were running a powerpole distribution block like @axorlov, I'd grab a couple of the t connector to power pole cables DXE has. As it is, I'm tempted, because my psu has power ports on the front.

I also spliced up a powerpole to 12v socket.

[wayoverthere]

On 11/6/2021 at 11:22 AM, wayoverthere said:

I was pondering this last night as I trolled the auction site. Already have a vertex vx4207 for 70cm and gmrs, and found a vx4204 (the vhf version of the same radio) for a tempting price...they're pretty much twins, down to the same mics.

What stopped me from pulling the trigger is a, lack of space in the truck, b, no huge need for vhf, as nearly everything around me on vhf has a linked UHF side, and c, it wasn't a huge gap price wise compared to just grabbing another dual bander.

i ended up grabbing a 4204 after all. what finally pushed me over was testing some stuff with my icom base, and how fast the fan kicks on.  the vertex have significant heat sinks, and get by without.  so the icom will move to the truck, and the 4204/4207 will be the base setup. will probably add a switch shortly, to have gmrs antenna on one side and the other side to a diplexer and gp1.

[WROA675]

Hey everyone, shifting topic back to the antennas...

After weeks of tx on the DB25G, it's become apparent that I need to move the bracket higher. As you can see in the enclosed picture I have the Larsen BSA 450 mounted to an old Dish bracket (antenna on the right rear) and will be moving it closer to the peak of the A-frame.

At the same time I'm going to move the 7900D (left front-for the QYT) to the same frame, so both will clearly be well above the roofline (but still unseen by the HOA from the ground).

Two questions here (first one is similar to the question I asked earlier about the units being in close proximity):

1) is there a minimum distance the two antennas should be apart from each other (will not be transmitting on both radios any the same time)?

2) do they both need to be grounded somehow and does that protect my radios from lighting strike surge (rainy season is coming)?

[gortex2]

Being neither has a true ground plane it may be worth adding a ground plane vs moving them. Maybe its just the picture but i see no ground planes on either antenna. Those are both mobile antenna's so without a ground plane are both not going to do much. 

[generalpain]

That metal chimney will have unintended consequences for your SWR and for where your signal will go.  I can't tell based on a photo, but raising the antennas above that chimney will eliminate any problems (in addition to adding a ground plane as kb2ztx advised).

Regarding the distance between two antennas...  it doesn't matter that you're not transmitting on both at the same time-- if they are too close, you could damage the one that is not transmitting.  Raising one higher than the other will help with this problem. 

Can you add a mast to the one that is attached to the chimney to get it above the chimney?  That and adding ground planes will help immensely.

[WROA675]

4 hours ago, kb2ztx said:

Those are both mobile antenna's so without a ground plane are both not going to do much

Thank you the input @kb2ztx. I will add a ground plane to the 7900D, as it is a mobile lid mount. As for the Larsen, I couldn't find anything about it being a mobile antenna, as it is advertised as a base antenna with 4.5 dB gain, and has four radials around its base already. Do you think it still needs a ground plane?