Please help your fellow skip shooter

[lonestarbandit]

Lucky for you, they still sell a MQ HG 2SC2879 16D08 set. For $128, you can repair the amp your self. Just unsolder the old transistors and pop in the same exact new ones:

HG(HuaGao) 4 PCS 2SC2879(MQ, Match HFE) build by China HG semiconductor | eBay

New 2SC2879 is produced by HG China. Can replace Toshiba 2SC2879 well. HG 2SC2879:+2.0 USD each. We will match HFE for this 4 PCS 2SC2879. The HFE will be marked on the lids. HG 2SC2290:+1.7 USD each.

www.ebay.com

While you are at it, get some 10ohm .5 watt carbon resistors and replace the 4 that are there.

There are higher quality LP filters out there but you can probably reuse yours by simply pulling out the end of the coil that feeds through the grommet so the feedthrough wire is in the center of the hole and not pressing up against the left side of the grommet and arcing through the rubber to ground that is millimeters away. The stench is the burnt grommet.

Good Luck.

Thank you. No, that LP is never going back in line. I don't even know why I had it there other than old habits. This whole mess could have been avoided by not having it at all. I will undertake the repair of the LP, but when repaired it will go back in the parts closet unless I get some complaints.

 

[Xjeepguy]

Thank you. No, that LP is never going back in line. I don't even know why I had it there other than old habits. This whole mess could have been avoided by not having it at all. I will undertake the repair of the LP, but when repaired it will go back in the parts closet unless I get some complaints.

I thought with everything going digital you wouldn't need an external LP filter at all. Lots of decent old Drake and or Bencher LP filters out there. I wouldn't have anything Paradynamics in your house lol .

 

[Shadetree Mechanic]

Thanks so much! BBIs video and your thread was helpful as well. Mine are marked @64 gain so assuming I can locate one @ that gain I'll try that 1st. Guess ill skip the C models for now then. Much appreciated Shade.

I wish it was that easy. The gain marked on your transistors is from when they were new. The best way is to pull them out and measure them, because the gain is gradually reduced over time just by using it. But you could try it, it might work out ok. For a while.

 

[999]

Thanks so much! BBIs video and your thread was helpful as well. Mine are marked @64 gain so assuming I can locate one @ that gain I'll try that 1st. Guess ill skip the C models for now then. Much appreciated Shade.

No, no, no... that was the gain when they were installed. As soon as you start using them, the gain drops. You'll need to pull out, at the very least, it's companion and measure it to see what the current gain is. If it were me I would test all of them to be sure they are still good.

 

[lonestarbandit]

No, no, no... that was the gain when they were installed. As soon as you start using them, the gain drops. You'll need to pull out, at the very least, it's companion and measure it to see what the current gain is. If it were me I would test all of them to be sure they are still good.

Yes. Rooster in TN just made a video due to myself messaging RE pills.
I am both embarrassed for my intial lack of understanding but also glad for the explanation and maybe his video will help others also.

 

[lonestarbandit]

I thought with everything going digital you wouldn't need an external LP filter at all. Lots of decent old Drake and or Bencher LP filters out there. I wouldn't have anything Paradynamics in your house lol .

I took it apart. Repaired it, replaced grommets, added heatshrink for extra safety and adjusted position of coils and added some electrical tape on one of the separating walls just because it looked too close to the metal for my liking especially after what just happened with the arcing. It is NOT going back in line this was an expensive and annoying lesson regarding quality equipment.

 

[lonestarbandit]

Lucky for you, they still sell a MQ HG 2SC2879 16D08 set. For $128, you can repair the amp your self. Just unsolder the old transistors and pop in the same exact new ones:

HG(HuaGao) 4 PCS 2SC2879(MQ, Match HFE) build by China HG semiconductor | eBay

New 2SC2879 is produced by HG China. Can replace Toshiba 2SC2879 well. HG 2SC2879:+2.0 USD each. We will match HFE for this 4 PCS 2SC2879. The HFE will be marked on the lids. HG 2SC2290:+1.7 USD each.

www.ebay.com

While you are at it, get some 10ohm .5 watt carbon resistors and replace the 4 that are there.

There are higher quality LP filters out there but you can probably reuse yours by simply pulling out the end of the coil that feeds through the grommet so the feedthrough wire is in the center of the hole and not pressing up against the left side of the grommet and arcing through the rubber to ground that is millimeters away. The stench is the burnt grommet.

Good Luck.

I actually just bought 4x hg2879 from Rooster as way I see it he (and you all) saved me from future aggravation if unmatched group kept popping, so kinda owed the man that at least. Will save the 3 for spares for my 2 pill which has real Toshiba in it atm if God forbid something happened to it.

 

[lonestarbandit]

Good news all. Now I'm starting to get the beginnings of early parkinsons I'm afraid and my hand shakes a bit so the solder work isn't what I was once capable of.....but.....it is functional and I could have cleaned it up with some alcohol and gotten it all spanky new looking but just didn't. Anyway, thanks to all here and special thanks to Rooster and Shadetree for saving me from myself and swapping 4 pills not 1. Result shes doing 90-100 PEP more than new..... strange that.....but I won't complain!

 

[unit_399]

Nothing feels as good as repairing a piece of equipment, firing it up for the first time, and having it work even better than before. Great piece of work Lonestar.

- 399

 

[lonestarbandit]

Nothing feels as good as repairing a piece of equipment, firing it up for the first time, and having it work even better than before. Great piece of work Lonestar.

- 399

Well it isnt by far my first repair, however getting a shocker bonus of more performance than previous was sure nice!

 

[Shadetree Mechanic]

Glad you got it going, "I love it when a plan comes together".

 

[lonestarbandit]

I may have spoken too soon. For some reason my box has a stupid high SWR on the beam, it's OK on the omni. Not sure what's going on checking coax cables, switch etc but It's the most bizarre thing. I've tried different jumpers but any good AUUUDDIIIIO brings about the same SWR pegging. I'm guessing the connector at the antenna feed point has gone bad? This seems to be snowballing with no certain idea (in my mind) of what's happening.

1. 4 pill base soon as you AUDDDIO the SWR runs away and doesn't come back down.
2. This ONLY happens on the beam.
3. This does not happen at all on the little 2 pill mobile amp regardless of antenna - perhaps due to much lower power output?

 

[unit_399]

lsbandit -

I believe you hit the nail when you said it was a reaction to the higher power of the big amp. I'm assuming that your V-Quad is a Maco. I looked at their site, and the V-Quad's spec sheet didn't mention power handling capability.

Just a thought: Maybe it's a CMC current thing with the big amp. Possibly winding and putting a coax choke at the base of the antenna will help. Won't hurt.

Before you pull the antenna down, I suggest you call or email Tom Charles at MACO and explain the problem. He is a good guy, and always willing to help . 1-815 244 3500

- 399 J.J.

 

[lonestarbandit]

lsbandit -

I believe you hit the nail when you said it was a reaction to the higher power of the big amp. I'm assuming that your V-Quad is a Maco. I looked at their site, and the V-Quad's spec sheet didn't mention power handling capability.

Just a thought: Maybe it's a CMC current thing with the big amp. Possibly winding and putting a coax choke at the base of the antenna will help. Won't hurt.

Before you pull the antenna down, I suggest you call or email Tom Charles at MACO and explain the problem. He is a good guy, and always willing to help . 1-815 244 3500

- 399 J.J.

Indeed it is JJ. A brand new one. Though the coax line is from a previous antenna.
The paperwork I got with it said 2kw max on the stock Gama match. I'm certainly nowhere near that level. Maybe the gamma just doesn't somehow have a good connection to the rest of antenna idk. I figure I better check the pl-259 on the feedline as the last antenna it was connected to (a VQ3) perished in a tornado and storm gusts (had both at once and not sure which one did that actual deed of dropping it as was middle of the night after snapping the rotor) I gave it a look over when I built the new smaller antenna it seemed fine rang out ok but there is potential for a issue there.
Yes I've spoken to Tom back with the VQ3 and he was a great help. I'll have to give him a ring if it isn't the connector, as I don't know what else would do it.
I'm getting too old for this lol antenna is pole mounted about 30 feet up lowering it with all the weight at the top works like a fulcrum the wrong way round tough to hold on to her and have to be extremely cautious how she comes down or elements get bent and broken.
If I take it down there's zero reason to not redo the pl259 and check gamma connection and at least eliminate that from potential issues. May also try the choke idea because why not.
I took the big box (for me) out of line, went back to the little mobile cause God forbid the big box pops again I'd lose what few brain cells I have left.

 

[Dr_DX]

"Just a thought: Maybe it's a CMC current thing with the big amp. Possibly winding and putting a coax choke at the base of the antenna will help. Won't hurt."

+1