1kw plus broadband linear amp in mobile

Discussion in 'Mobile Radio' started by KR4IS, Sep 5, 2017.

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  1. KR4IS

    KR4IS Ham Member QRZ Page

    I have been running a 10/11m amp for 10m ..what concerns to amp if I was to load it up on 40m..the transistors are rated for 7mhz..the amp wants 50 ohm input and 50 ohm out put..I've looked at some broadband amp scematics for 80-10 and there is no band switch...so what am I missing..can I plug in my hf rig on 40m and with 5 watt drive get the 1k I do on 10? Kr4is.
  2. K0PIR

    K0PIR XML Subscriber QRZ Page

    What make and model amp is it?
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    You should try it, Then post in Radio Circuits, Repair & Performance.

    Good Luck.
  4. K4KWH

    K4KWH Ham Member QRZ Page

    Just a word of caution. IF it is one of those CB-style "10 Meter" amps, it likely lacks the filtering required even for amateur radio. I think the reason your schems lack a bandswitch in the diagrams is that the RF-keying circuit, common with CB amps is not exactly kosher. The other reason is that even if the amp loads on 7 Megs, without that filtering of the amateur amps, it could cause interference out the wazoo to other services, not to mention what they can do to the car's electronics. There's where one could get in hot water--the interference to other services. YMMV.;)

    Now with all this finger-wagging and "thou shalt nots";), OTH experimentation is the lifeblood, or should be, of amateur radio. What might happen if you attempt to use it on 40 Meters? Maybe nothing and it works fine. If the "woiks" aren't within range of 7 Megs, it may output at a reduced power, it may blow your drivers or finals. I'm assuming its a transistor amp? OR it might cause unacceptable interference. Make your XYL blow HER finals because you interfered with her TV programs:p:eek::D!

    SO try it and see! I have an old Messenger 800 watt amp that I (with help from a ham buddy) modded for 80-10 Meters. We added filtering, made few changes, and I ran it experimentally for a few months. It showed me that I don't need BIG power to have a successful mobile station. I got tired of it. I can do just about as well with an efficient HF mobile antenna and 100 watts + it isn't as much trouble to install and deal with--running all that extra heavy wire and switching into and under the car. Haven't used it years!

    I will close with a funny incident and something I did in mischief. I was at a stoplight one afternoon with my 800 watt amp. A car pulled up in the other lane running his BOOOM-BOOOOM-BOOM-RUMBLE stereo system. It was so loud it was vibrating my rump in the seat of MY car:eek:. I flipped on the amp and switched to AM. Keyed down for a few seconds. The "boom-boom-boom" stopped! The other car had rolled slightly forward and I could see the other driver, puzzled and confused, twirling knobs trying to figure out what happened!:confused: Oh, he still had music, (the regular car radio), but at a much reduced volume!!! (snicker):p Ain't I a stinker?:rolleyes:
    N5CM likes this.
  5. WD5IKX

    WD5IKX Ham Member QRZ Page

    I would spend my money on a good mobile antenna.

    John WD5IKX
  6. K4KWH

    K4KWH Ham Member QRZ Page

    Me, too! A lot less trouble! So many people have been led, or just assume, that big power is the key to radio, but its not. With my own screwdriver that I built (3" dia coil w/#14 copper wire @ 10 TPI), I can usually talk to anyone I need to, especially in an orderly net or QSO. I often got compliments on my mobile signal with that and 100 watts. Its out of the truck right now since I traded, but soon its going into the garage for an installation project. I expect to be back on HF soon! :)
    WD5IKX likes this.
  7. KR4IS

    KR4IS Ham Member QRZ Page

    Thanks guys for such an awsome responce,I've been following since my op.i have a lowpass filter and will use it..the Antena will be home brew sim to bug catcher designs..looking now for cheap hf rig I can mount in truck...I will experiment with a low power amp for I have a couple 300 watters and get a ham with spectrum analyzer radio to look for spurs..if anymore comments or anicdotal experiance ,meet them coming .tu agn.kr4is
  8. K6CLS

    K6CLS Ham Member QRZ Page

    Look really carefully at your RF exposure. Mobile setups don't have enough separation for both controlled and uncontrolled access at high power (> 100w)
  9. WD5IKX

    WD5IKX Ham Member QRZ Page

    I like that you plan to "home brew" a Bug Catcher style antenna. That is what I did and it works extremely well and cost less than $150. I often bust DX pileups and make contacts even when the band conditions are poor with only 100 watts. K0BG's website has great info to help you along. I have considered upgrading to a high end screwdriver but I just can't get past the Kilo-Buck price tag when my $150 special works so well. Building it yourself is a great learning experience and it's fun.
    Antenna rainbow.JPG

    John WD5IKX
    YF8RQN likes this.
  10. WA4SIX

    WA4SIX Ham Member QRZ Page

    For a CB/10 Meter amp to be correct, each push pull pair needs the proper temperature compensating bias. You will also want to add a keying line direct from the rig & bypass the RF keying. Negative feedback adjusted for lower freq's. Lastly, as stated, you will need proper low pass filtering for the used bands.
    It's quite a bit of work, but can be done. PM me for some better details. I have done this several times.


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