HF on the cheap.

Discussion in 'Survival Communications' started by WastedDaze, Apr 26, 2017.


  1. WastedDaze

    WastedDaze Monkey+

    Or "do I really want to repair this free radio?"

    In January an older ham I talk to said he had a bunch of old boat anchor gear (old tube ham and mil-surp radios) he needed to get rid of. If someone didn't come a take it away he was going to scrap it. So I drove to his place... 350 miles one way. A friend went with me and we loaded up the entire back of my Suburban with about 800-900 lbs of old radio gear... He lived about a stones throw from the ocean and this stuff was pretty rusty having been stored in a shed.

    Anyway, in the midst of this stuff was a newer marine band transceiver. Newer than 1945 but kind of old for synthesized solid state gear... The SEA222 transceiver hit the market in 1985 and was built and sold into the early '90s. Here's a photo of a nice looking SEA222 I found on the internet.
    [​IMG]

    All the boat anchor stuff was sold at a ham radio swap meet but I kept a few items like the SEA222 just to see if I could get it operational again. It had no display and no receive audio.
    Here it is on the bench.
    [​IMG]

    Fortunately Bruce (BTpost) had a service manual he loaned me.
    The display power supply has a filter made from two 22 uf 25v tantalum caps and a 420 mh molded inductor to keep the switching hash of the power supply off the DC supply. Well, tantalum caps are known for going bad and shorting out and they did. This stressed the inductor beyond it's limits and it opened so there was no DC supply to the switching regulator IC. Thus no display.
    I used a couple electrolytic caps in place of the tantalums with a .01 uf mylar caps strapped parallel across each one. Found a choke coil at 370 mh with heavier wire and figured that was close enough.
    Here's an after photo of the repair. Yeah, the two orange caps with the green caps on top and the PI wound choke between. Not real elegant but it works.
    [​IMG]

    Now that I got the display working I found that the problem with receive audio was just a jumper missing from the accessory connector on the back of the radio. I programmed the radio for 60 mtr Amateur channels and called the ham who gave me the radio. We talked for a while, he was impressed to hear how good it sounded. When I got off the air I noticed the keypad started getting flakey. Tracked the problem down the flex cable that connected the keypad to the main board. The flex cable was disintegrating and it's part of the keypad which is integral to the front panel laminate overlay. To repair the flex cable ment the keypad had to be replace which ment the front panel overlay had to be removed... Which I didn't want to do, at first... but I went ahead and did it anyway.
    Here's the keypad and overlay removed. You can see little holes in the conductive strips on the flex cable.
    [​IMG]


    So using some black sign vinyl and an aftermarket keypad I rebuilt the panel.
    [​IMG]

    Now things were coming together. Reassembled the radio and turned it on... the display now had the "UNLOCK" error code! Yikes!
    After studying the schematic of the dual Phase Locked Loop circuit I finally came to the conclusion that the CPU was not sending the data to the second PLL ICso it didn't know what frequency it was supposed to be on, this causes the PLL circuit to be unlocked. I contacted SEA Comm and they had a good used CPU they sold me and once plugged in we were back in business.

    Here it is on 20 mtrs. I even checked into the Maritime Mobile net on 14300 kc.
    [​IMG]

    The radio will receive by directly keying in frequencies on the keypad then pressing the ENT button. This is receive only mode.
    The receiver covers 500 - 24000 kc or .5 - 24 Mc.
    The transmitter works from 1500 - 23000.
    Transmit power is 150 watts peak.
    There are 100 user programmable memories.
    It transmits USB, AM & CW (with optional CW board). I plan on building the CW option board and installing it. There was also a LSB option but finding a LSB filter for 6.4 MHz IF might be difficult.
    I have less than $100 into the parts but the education experience gained I think is far more valuable. Plus I enjoyed repairing and modifying it. It's a hobby radio.

    Some of the newer marine band radios have both USB & LSB.. They are also getting easier to find and prices are coming down on used gear since a lot of ships are going sat-comm. They make a great backup rigs and are far easier for the uninitiated new ham to use. A good alternative comm radio for you monkeys! Especially if you don't have to repair it!
     
  2. ghrit

    ghrit Bad company Administrator Founding Member

    I am impressed. Good job!!!
     
    sec_monkey likes this.
  3. Tevin

    Tevin Monkey+++

    Well dude, I've been wrenching on communications electronics professionally for...a really long time. And you took that old dog further than I would have bothered.

    As you mentioned, that SEA222 isn't worth much as a useable radio or as a swap meet item, but the learning experience is priceless.

    Very good! I'm truly impressed! :5s:
     
    sec_monkey likes this.
  4. WastedDaze

    WastedDaze Monkey+

    Thanks guys.

    Tevin,
    I used to work in LMR, became service manager of the shop. Got a better paying job working in industrial process control. So I work on radio gear more for the enjoyment. I must say I'd rather work on communication gear but it just doesn't pay that well. At least not around here.
     
    Tevin, DKR and sec_monkey like this.
  5. Bandit99

    Bandit99 Monkey+++ Site Supporter+

    @WastedDaze I am in the same boat as @Tevin and have to agree with him as been doing something involving communications and electronics my entire adult life so... really, sincerely impressed. Well done! Congrats!
     
    Tevin and sec_monkey like this.
  6. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    If you put the Radio in Test Mode, it can transmit across the. Whole HF Band up to 23 MHz... and you can load those Frequencies into the Memory Channels..

    and on another note, SEA did make a USB/LSB Kit for the SEA222, as well as a CW Kit...

    Back in the day, I used to use the Cannery Radios to check into the Alaska Pacific Net on 14292.0Khz USB while doing my rounds, out in Bush Alaska... was nice to keep in touch, without hauling my own radio with me...
     
  7. DKR

    DKR Raconteur of the first stripe

    It doesn't "pay well" anywhere. I get it. I worked as a USAF ground radio guy for 22 years - now I'm a technical writer pulling down about 3x what I could get working LMR/SMR. It's all pretty much board swapping now anyway.

    Thanks for the posts.
     
  8. WastedDaze

    WastedDaze Monkey+

    DKR,
    I know a guy in Florida that is a marine radio tech, has his own shop. Now he's doing well. We don't have that kind of clientele on the Oregon coast.

    Yes, the newer radios are getting harder to work on with fine pitch SMDs. Its come down to board swapping. It's all one board on most portables anyway. And they're getting to be SDRs with knobs too. System on a chip. It's cool and kind of sad at the same time.
     
    Last edited: Apr 26, 2017
  9. WastedDaze

    WastedDaze Monkey+

    Bruce,
    If I could find a 6.4 Mc USB filter I'd add that. You see in the freq conversion scheme SEA used they are using a LSB filter to get USB. So you need a USB filter to get LSB.
     
  10. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    In the later SEA Models, they used a single Filter, and switched the IF Frequency, to use it To generate the Opposite Sideband... My friend doesn't have any more of the LSB Kits for the SEA222s...
     
  11. Tevin

    Tevin Monkey+++

    LMR typically doesn't pay well but I was lucky enough to land a gig at a Really Huge Telecomm Company. I don't do any analog radio; most of my work involves fiber optic transmission gear, cell towers, and backup power. I get good benefits, 401K, all that stuff.

    But yeah, there are not too many safe harbors anymore, and no one troubleshoots down to the component level.

    Keep on truckin'...
     
  12. WastedDaze

    WastedDaze Monkey+

    Bruce,
    Yep, high side / low side injection will get you both sidebands from a single xtal filter.
    I was looking to do something like that with the 222 but didn't want to re-engineer the radio.

    Below is a Canadian Marconi CP-34 (aka: AN/PRC-514) packset that I was able to get USB and LSB with a single filter using the DDS VFO I built. Being a crystal controlled single conversion rig made it that much easier. Used it on 75mtr LSB, 60mtr USB and 40mtr LSB. Fun stuff.
    [​IMG]
     
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