In reply to GM4CFS:
I `d better reply to Glyn as he caught both my summits today. I know condx were poot today, I use Yaesu ft857 (software modded with broadbander) an inverted vee dipole with the centre at 5m above ground. The antenna has power pole links for 10m, 20m, 40m, 60m,
Steve G1INK
In reply to GM4CFS:
Hi Glyn
FT817 on the summits…old one and software mod. IC706 Mk1 at home. I think I removed some surface mount diodes or links on this one, but it was a long time ago so memory has faded. I also have a IC756Pro which is widebanded, again removing SM diodes, but I don’t use it as I don’t have a spectrum analyser and 5MHz is on the edge of the bandpass filter so spurious output is a high probability.
73 John GW$BVE
In reply to GM4CFS:
Chaser.
TenTec Paragon (now replaced by an IC-756);
Yaesu FT-897, software modded for wide Tx coverage;
Alinco DX-70TH (now replaced by an IC-706MkIIG),
early (used) FT-817, software modded for wideband Tx (/P WAB areas).
73
Graham G4FUJ
In reply to GM4CFS:
Hi Glyn,
I use an FT817 (old model) and an FT2000 (home only!!!) both were modified by M,L & S for me. The latter rig required some zero ohm resistors removing I think. Home antenna is 30m longwire end fed over roof to a tree max height 8m tuned with MFJ993.
Activator antenna, when I eventually get near some hills this year, will be a slightly long 40m dipole in inv V format on a Sota pole, 300 ohm ribon feeder, balun 4:1 and an elecraft T1 tuner.
I am hoping to get either a FT857 or FT897 for my trip to EI but am not certain which to get. I want to be able to run 100W from the holiday cottage and QRP on the hills.
cheers
Mike G4DDL
In reply to G4DDL:
antenna [snip] will be a slightly long 40m dipole in inv V format on a Sota
pole, 300 ohm ribon feeder, balun 4:1 and an elecraft T1 tuner.
Is the advantage of having a wide range of frequencies that the antenna tunes against worth the weight penalty of the balun and tuner?
I know the T1 is small and not too heavy, but my view is that a pre-tuned antenna with removable links and hence resonant on the bands of interest is simpler, more efficient, lighter and less prone to equipment failure. Possibly a good example of the less is more school of thought!
Elecraft gear has a high reputation and deservedly so, but I wonder how lossy the overall system would be compared to a resonant antenna. Probably not a big issue for CW ops, but more so for SSB ops.
I’d be most interested in any views on the subject of using tuners vs. resonant antennas. I’m sure there are lots of people with much more experience than me on this.
Andy
MM0FMF
In reply to MM0FMF:
Hi Andy,
I’ve found that resonant antennas carefully pruned in the ideal conditions of the back garden often are not when draped over trees, fenceposts and other convenient supports in the field and thus prefer the ATU approach. QRP ATUs can be made very light, a built in resistive SWR bridge is very handy for “safe” tuning up. My latest one (balanced Z-match type, for use with twin fed dipoles made from computer ribbon cable, none of that heavy coax!) weighs in at about 250g, not an issue for me.
Reliability is an issue, it “died” atop Snaefell earlier this year and severely curtailed my 60m operation from there. Maybe the belt and braces solution is resonant antennae with an ATU to tweak the tuning!
73 de Paul G4MD
In reply to MM0FMF:
Hi Andy!
Elecraft T1, 300 ohm or so ribbon, 40M Inv V and 817 used by myself. No balun. Loads up on all bands 80-10M. Used this for a couple years to good effect.(always load up on lowest power - good operating practice - hi!)Short centre of V to use on 80M. Bit directive though. Still using original PP3 in ATU. Great little piece of kit. Fitted into a spare PDA holder for protection.
73
Jack (;>)
In reply to MM0FMF:
Elecraft gear has a high reputation and deservedly so, but I wonder
how lossy the overall system would be compared to a resonant antenna.
Probably not a big issue for CW ops, but more so for SSB ops.I’d be most interested in any views on the subject of using tuners vs.
resonant antennas. I’m sure there are lots of people with much more
experience than me on this.
The theory says that the bigger antenna has higher radiation resistance. The losses come mainly from the antenna wire and from ground currents. In SOTA operation the antenna is often not very high so I would expect that the ground losses are important. If the radiation resistance is much higher than these losses then the antenna gain is also high and it radiates power well to some direction. The tuner losses can be important if you are using small antenna, that is in terms of used wave length. If you compare two dipoles, one tuned with a tuner and the other self resonating, I would not expect to see too much difference. In practice you need some device, e.g. SWR meter, dip meter or antenna analyzer, to check the resonance of the antenna. The otherway to think this is to let an automatic antenna tuner resonate the antenna and ground system on the hill.
73, Jaakko OH7BF/F5VGL
In reply to G3TJE:
Hi Peter,
Sorry I missed your post, my other post about the FT920 mod was just the green wire mod and not removing any smd’s. I think I was getting mixed up with my TH7-FE.
I did my mod a few years ago, from what I remember I did the “green wire” mod and that worked for me. My radio was a UK bought one.
I looked up DK mods for mine at the time and crossed checked that with others on the net (now requiring registration). Note the software mod for US 920’s that will will cause damage.
Below is the mod which I believe I did.
Good luck,
Regards
Roger MW0IDX K3IDX
Subject FT-920 Mod
The following mod is for USA MARS/CAP operation
1-remove bottom cove
2-remove dsp unit and cut or remove green wire that connected between
r2544and q2510
3-replace dsp unint
4-press and hold step and lock button and power on
5-enter 1984129 than oress ent
6-test the radio for correct oper
7trun the radio off and replace bottom cover
8-the modification is now completed
please post on you wab site for radio mods
this mods dose work i done it to my ft920 thankyou anthony fernandez
136franklin st elizabeth nj 07206
email tony1576@juno .com
From: "Yaesu Tech Support"
To:
Sent: Thursday, April 27, 2000 2:56 PM
Subject: FT-920 Modification
Greetings,
We have received many calls regarding the frequency expansion modification
for the Yaesu FT-920 which is currently posted on your web site. The zip
archive contains an executable file that is meant to “flash” the EPROM of
the transceiver to allow the transmitter to operate outside of the amateur
bands.
This software will cause irreversible damage the EPROM in US version
transceivers. Replacing this EPROM is quite costly and is not covered under
warranty. Unfortunately, many FT-920 owners have found this out the hard
way.
To help prevent additional damage to the ever-growing fleet of FT-920s, we
request that this modification information be removed from your site. We
appreciate your assistance, and would be happy to answer any questions you
may have in this regard.
73,
Mike Krueger, N6MIK
Technical Support, Amateur Products Division
Yaesu U.S.A.
562-404-2700 Ext. 242
From: "chris hays"
Sent: Wednesday, February 07, 2001 11:06 AM
Subject: FT-920 Frequency Transmission/Expansion Mod
The following is a mod to the Yaesu FT-920 to expand transmit frequency
coverage. Do this mod at your own risk !
- Remove top and bottom covers.
- Remove the DSP unit, and cut or remove the Green wire that connects
between R2544 and Q2510. - Replace the DSP Unit.
- Press and Hold STEP and LOCK buttons when powering on.
- Enter the following code: 1-9-8-4-1-2-9
- Test the radio for proper operation.
- Turn the radio off and replace the top and bottom covers.
- Mod is complete.
Note: This mod is for Lot 8 and up.
This mod will allow transmission on MARS and other frequencies.
If you do not operate MARS, then don’t do the mod.
73
Chris