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More Power on 2m FM?


#1

Most of us use handheld transceivers for 2m FM SOTA activations. Pretty handy and compact.
I decided to try out one of the low cost mini-transceivers (Tytera TH-8600) with 25W output. It is a nice upgrade that makes a difference on longer distance QSOs.

Details written up here:
http://www.k0nr.com/wordpress/2017/10/more-power-vhf/

73, Bob K0NR


#2

Bob,
Good write up! Yes, getting above the noise floor is a make or break on many contacts. BTW, my 440 FM distance record is 106 miles, measured from gps locations. Used one of N6NB’s quagi plans to make the antenna, 12 gauge wire and scrap wood construction. Initial contact was done with 5 watts, part two of the game was to open the autopatch on the repeater and make a call to the club president. This is where power came in - needed to go to high power, 35 watts, to open the autopatch and place the call. Yes, power matters, and yes antenna matters.

73, Howard KE6MAK


#3

Thanks, Howard!

Here’s a 5W 2m FM contact between two 14ers in Colorado at 160 miles on video:


#4

I’ve considered using a Kenwood TM-281 mobile (25W on low) that I have lying around, more for the novelty of activating with a different radio than for the more powerful signal. Also, putting it on the bike rack of my mountain bike for some hills in SW Wisconsin where gravel roads pass through the activation zones of summits on privately owned farmland.


#5

Yaesu FT-90 is the set to have, small and light yet powerful.

A few people in the UK have done activations using 2m FM only sets at the 25-45W level. Of course the issue with such activations is the speed at which high power FM will suck the bejesus out of your batteries.


#6

SWEET! My 106 pales in comparison…guess I have a new goal now :slight_smile:


#7

My preference is a Yaesu FT-817 driving a small 25W output linear, my preferred mode being 2m SSB. When I switch to FM, I usually lower the power out on the 817 to a watt which gives me 10W output from the amplifier. If a bit more is required, I can up the power, but the batteries do take a hammering and the difference between 10 and 25 watts is marginal.

Using mobiles (including the FT-857) is usually a less efficient use of battery capacity as they have a higher current take on receive. Mobiles also may be significantly heavier as weight will not be a factor that is considered in their design.

My linear has a preamp which helps with low signal strengths in return for minimal current take. Using an antenna with gain has the equivalent of upping the power without expending any battery capacity and improving the received signal.

73, Gerald G4OIG


#8

I agree that the FT-90 is a nice compact rig…hard to find these days.
The Tytera radio draws 4A on transmit at 25W, which is not too bad for today’s battery technology.
Going much higher in power gets you into the 8 to 10A range, which is really pushing it.

73, Bob K0NR


#9

Especially fully working Bob. Many are now QRP or single band due to excessive heat seeing off the output block. I think the later ones were better at monitoring their PA temp and throttling back the power when hot.

I would like to run a challenge of some kind where 2m FM featured, possibly just using a handheld + rubber duck. The idea to show to newbies that even a handy is viable for SOTA when people are listening. The problems I see are that such an event(s) would work fine in Europe / Asia where we have high population densities. But USA and VK/ZL etc. would be put at a disadvantage. Sure it would work in metro areas and their environs but for those out in sparesly populated areas, well they would find a challenge!


#10

Does the Tytera have a selectable receive attenuator to reduce intermod?


#11

Rather than more power I have found antennas make a big difference.

A telescopic antenna that extends to a full quarter wave on my icom v85 is much much better than the stubby helical. and another longer antenna that goes out to 3/4 is even better.

And also have found that horizontal polarisation even using the typical HT with antenna horizontal gives better range than using it vertical.

A wire horizontal dipole about 8 ft up the pole works even better. 100 km on ssb quite easy, 200km if one has a small beam. Horizontal is best.


#12

ISTR a joke about pianos, women and being horizontal :wink:


#13

No selectable attenuator on the Tytera.


#14

mainly the electrons…


#15

Great article! Tempted to purchase this radio!!!


#16

I like using my circa 1980s Yaesu FT-1500M, powered by a 7 AH LiPo. It does me, and if you operate contest style the battery will last for several 2m FM activations at the 40 watt level. Can always hit the low or mid button when the chaser is strong and run 5 or 15 watts instead. If within reach of a conurbation, say from North Wales to Liverpool / North West England, then 5 watts from a handheld to a dipole is usually adequate though.

I use an end fed vertical dipole on a 4m pole which I prefer to a beam for ease of use in the extreme circumstances we often find ourselves in when activating. I don’t know how K0NR and W0STU manage to log the QSOs with a beam in one hand and the radio in the other. Maybe they are recording it on a phone or an assistant is logging :wink: The weather was good and just one QSO was shown in the film in which case one contact can be easily memorised and written up later - the distance (160 miles) was impressive!

Have a good holiday in EA8 Andy.

73 Phil G4OBK


#17

My logging procedure is:
Make the radio contact
Remember the callsign
Gently lay the yagi on the ground.
Write the information into the log
Repeat


#18

That’s a fine technique and it sure saves the job of both carrying a pole to the summit and then clamping and guying your yagi to the pole - not easy on a composite thin walled lightweight pole.

73 Phil


#19

This is how I got my start in SOTA, and it can be very effective. To date my distance record is 165km with 1W, I consider it my first SOTA “DX”! A few months ago I activated a summit in ZL near Christchurch with a borrowed HT (thanks Rik!) and a rubber duck antenna. To date it remains the highest activated summit in ZL.

P.S. Unfortunately the HT did not survive reentry to the UAE. May we now take a moment of remembrance for our confiscated equipment, retired before its time…


#21

Hi Andy

If the challenge were to take place could I suggest that any 2m FM handheld be allowed (max 5 watts) but the rubber duck is replaced with a simple retractable whip such as the excellent and effective RH770 whip which can be purchased very cheaply from China / Hong Kong.

https://www.ebay.co.uk/itm/Centre-Loaded-Telescopic-Dual-Band-Antenna-SMA-Male-for-Yaesu-Icom-Radio-RH-770/272463396898?epid=2134855177&hash=item3f70158022:g:KEwAAOSwj85YN7G0

73 Phil