|
|
Post by BBB on Dec 8, 2012 10:48:15 GMT -5
My Galaxy Saturn has a low RF power output for some reason. With the RF power knob set at max it will only dead key at 1/2 watt and only swing to 5-6 watts. Similar issue on either sideband with the exclusion of a carrier.
This is a dual final radio based on the Galaxy EPT 360014B board or DX77 mobile I believe. I tried rocking the bias driver pots, among others, to see if that would wake it up, but no luck. The low and high power pots are set normally.
I can make up for the low power by using a 2 pill amp and the audio is fine. Almost seems like the radio is transmitting on the pre-driver only? So can a radio like this have both finals bad and still transmit with just the pre-driver and achieve 5-6 watts and/or can one final be bad and still transmit?
Also I checked the DC supply and it was maxed out at 11.5 VDC then drops to around 10.5 VDC when keyed. That seems a little low as well but I wouldn't think enough to cause such a low RF output?
|
|
Sandbagger
Administrator/The Boss 
Posts: 6,247 
|
Post by Sandbagger on Dec 8, 2012 20:22:33 GMT -5
My Galaxy Saturn has a low RF power output for some reason. With the RF power knob set at max it will only dead key at 1/2 watt and only swing to 5-6 watts. Similar issue on either sideband with the exclusion of a carrier. This is a dual final radio based on the Galaxy EPT 360014B board or DX77 mobile I believe. I tried rocking the bias driver pots, among others, to see if that would wake it up, but no luck. The low and high power pots are set normally. I can make up for the low power by using a 2 pill amp and the audio is fine. Almost seems like the radio is transmitting on the pre-driver only? So can a radio like this have both finals bad and still transmit with just the pre-driver and achieve 5-6 watts and/or can one final be bad and still transmit? Also I checked the DC supply and it was maxed out at 11.5 VDC then drops to around 10.5 VDC when keyed. That seems a little low as well but I wouldn't think enough to cause such a low RF output? Usually, when output is under a watt, that usually is a sign of a bad final. But before condeming the final, check the collector voltages on the driver and final. Thy should be somewhere around 6 volts on AM, and near the 12 Volt supply rail on SSB. If the voltage is low, you may have a problem with the AM regulator circuit. |
|
|
|
Post by Night Ranger on Dec 9, 2012 15:47:48 GMT -5
My Galaxy Saturn has a low RF power output for some reason. With the RF power knob set at max it will only dead key at 1/2 watt and only swing to 5-6 watts. Similar issue on either sideband with the exclusion of a carrier. This is a dual final radio based on the Galaxy EPT 360014B board or DX77 mobile I believe. I tried rocking the bias driver pots, among others, to see if that would wake it up, but no luck. The low and high power pots are set normally. I can make up for the low power by using a 2 pill amp and the audio is fine. Almost seems like the radio is transmitting on the pre-driver only? So can a radio like this have both finals bad and still transmit with just the pre-driver and achieve 5-6 watts and/or can one final be bad and still transmit? Also I checked the DC supply and it was maxed out at 11.5 VDC then drops to around 10.5 VDC when keyed. That seems a little low as well but I wouldn't think enough to cause such a low RF output? Usually, when output is under a watt, that usually is a sign of a bad final. But before condeming the final, check the collector voltages on the driver and final. Thy should be somewhere around 6 volts on AM, and near the 12 Volt supply rail on SSB. If the voltage is low, you may have a problem with the AM regulator circuit. The Galaxy Saturn service manual says that is a common problem with that radio, and to replace the bias adjustments on the finals. Night Ranger |
|
|
|
Post by BBB on Dec 9, 2012 21:27:56 GMT -5
Power supply is fine. I was looking at the 10V supply to the frequency counter. There's 14V to the main board. Both 1307 finals had continuity one way on the NPN C-E junction. Not so good. I'll may do a IRF520 Mosfet conversion since the 2SC1307/ 1969 replacements cost more than a steak dinner now  |
|
|
|
Post by Night Ranger on Dec 10, 2012 11:21:30 GMT -5
Power supply is fine. I was looking at the 10V supply to the frequency counter. There's 14V to the main board. Both 1307 finals had continuity one way on the NPN C-E junction. Not so good. I'll may do a IRF520 Mosfet conversion since the 2SC1307/ 1969 replacements cost more than a steak dinner now The 2sc2166 and 2sxc1969 transistors are much more robust than the IRF520/ERF2030 mosfets. Those blow easy. I already toasted the finals in my Magnum 257 once. I'd stay with the 2sc1969 finals with the 2sc2166 driver. MAGNUM S-9....OUTPUT MOSFET REPLACEMENT...IRF520N www.youtube.com/watch?v=72iZdrmLvhgNight Ranger |
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 10, 2012 12:43:10 GMT -5
Power supply is fine. I was looking at the 10V supply to the frequency counter. There's 14V to the main board. Both 1307 finals had continuity one way on the NPN C-E junction. Not so good. I'll may do a IRF520 Mosfet conversion since the 2SC1307/ 1969 replacements cost more than a steak dinner now The 2sc2166 and 2sxc1969 transistors are much more robust than the IRF520/ERF2030 mosfets. Those blow easy. I already toasted the finals in my Magnum 257 once. I'd stay with the 2sc1969 finals with the 2sc2166 driver. MAGNUM S-9....OUTPUT MOSFET REPLACEMENT...IRF520N www.youtube.com/watch?v=72iZdrmLvhgNight Ranger I would agree. The MOSFET parts that they tend to use for CB conversions are designed for switching applications (which is why they're so cheap). Since they are designed to be switched (either on or off), there is a very narrow linear range that can be used for analog amplification. It's very tough to get the bias right, and keep it there over temperature and voltage fluctuations. Add a little too much bias and POOF! I know the price of the older Japanese parts is becoming ridiculous, but there are some companies out there who are making knock-offs of the older bi-polars and some of them actually WORK (or so I've read). It'a also a great reason to pick up old junk parts radios on the cheap. Sometimes the sum of the parts really is worth more than the whole..... |
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 10, 2012 12:47:36 GMT -5
Power supply is fine. I was looking at the 10V supply to the frequency counter. There's 14V to the main board. Both 1307 finals had continuity one way on the NPN C-E junction. Not so good. I'll may do a IRF520 Mosfet conversion since the 2SC1307/ 1969 replacements cost more than a steak dinner now If the parts are measured out of circuit, you should see low resistance between the Base and Collector and Base to Emitter in one direction only. Sometimes I have run across parts that have some resistance between the collector and emitter, and still are good (  ?). Double check the bias circuit. If the bias voltages are way out of whack, this may cause a problem. |
|
|
|
Post by gator7 on Dec 11, 2012 8:41:53 GMT -5
I had a Galaxy 98 VHP, The MOSFETS would blow if you looked at them wrong. Had 8 MOSFETS, after the 3rd time got rid of the rig.
Huge problem with heat with that radio.
73
|
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 11, 2012 14:29:40 GMT -5
I had a Galaxy 98 VHP, The MOSFETS would blow if you looked at them wrong. Had 8 MOSFETS, after the 3rd time got rid of the rig. Huge problem with heat with that radio. 73 I'm not surprised at all to hear that. I am surprised that radio manufacturers are actually making radios with those finicky switching MOSFETS. They aren't designed to be used as amplifiers. |
|
|
|
Post by gator7 on Dec 16, 2012 9:07:57 GMT -5
I guess the cost of Mosfets out weigh the price to repair the radios. It has made me stay away from Galaxy Mosfet driven radios.
To bad, The 98 VHP is a very nice radio. Just likes to blow up often.
73
|
|
|
|
Post by Night Ranger on Dec 16, 2012 10:41:51 GMT -5
I guess the cost of Mosfets out weigh the price to repair the radios. It has made me stay away from Galaxy Mosfet driven radios. To bad, The 98 VHP is a very nice radio. Just likes to blow up often. 73 Those Galaxy radios always seem to be off frequency on sideband. When someone comes on 38 LSB and they are way off frequency from everyone else you've got a about 4 to 1 chance of correctly guessing they are on a Galaxy. I was listening to channel 38 LSB as I was driving up I-77 yesterday, and some guy out in skip was way off frequency from everyone else. Sure enough he was on a Galaxy 959. I had already correctly guessed he was on a Galaxy before he even told the person he was talking to. The DX2547 base seem to be the most likely to stay on frequency of the bunch although I've heard it basically has the same board as the 959. Night Ranger/South Carolina 116 |
|
|
|
Post by BBB on Dec 17, 2012 8:31:28 GMT -5
If I were to look for a inexpensive "donor" rigs, which ones would be guaranteed to have the 2sc2166 and 2sxc1969 transistors?
Like you said, if I could pluck them locally for say $10 a piece, I would be ahead of the game and would start a bone yard.
Thanks for the replies.
|
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 17, 2012 8:48:04 GMT -5
If I were to look for a inexpensive "donor" rigs, which ones would be guaranteed to have the 2sc2166 and 2sxc1969 transistors? Like you said, if I could pluck them locally for say $10 a piece, I would be ahead of the game and would start a bone yard. Thanks for the replies. Fortunately, you don't have to be limited to just 2SC-1969's for finals. 2SC-1307, or 2SC-2312's would work just as well. So just about any newer (meaning not quite a "classic") 40 channel SSB rigs will have one of those finals. The 2SC-2166 driver is common in most Uniden chassis radios. |
|
|
|
Post by BBB on Dec 18, 2012 16:10:34 GMT -5
The donors have to be a 40 channel SSB rig. 10-4 Rodger Alrighty. Thanks.
|
|
|
|
Post by BBB on Dec 18, 2012 16:27:47 GMT -5
Here might be a boxed solution. A self contained add on amp section similar to the RFX-75 called the RFX-150 (150-200 watts oh yea): www.bellscb.com/products/accessories/Powerband/RFX-150.htmlI bet it relies on the pre driver and at least one of the finals being good. I'll have to write them and ask. |
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 18, 2012 17:19:25 GMT -5
Here might be a boxed solution. A self contained add on amp section similar to the RFX-75 called the RFX-150 (150-200 watts oh yea): www.bellscb.com/products/accessories/Powerband/RFX-150.htmlI bet it relies on the pre driver and at least one of the finals being good. I'll have to write them and ask. In my book that's spelled - K L U D G E. |
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 18, 2012 17:22:39 GMT -5
The donors have to be a 40 channel SSB rig. 10-4 Rodger Alrighty. Thanks. There are some late model 23 channel SSB rigs that will work as well, but you have to know which ones have the TO-220 style power tab transistors, and which ones had the TO-5 can style. You want the power tab style. |
|
|
|
Post by BBB on Dec 19, 2012 11:50:34 GMT -5
A kludge (or kluge) is a workaround, a quick-and-dirty solution, a clumsy, inelegant, difficult to extend, hard to maintain yet effective and quick solution to a problem, and a rough synonym to the terms "jury rig", "Jugaad" or "jerry rig".
HAha, hehe
|
|
Sandbagger
Administrator/The Boss
Posts: 6,247
|
Post by Sandbagger on Dec 19, 2012 12:30:36 GMT -5
A kludge (or kluge) is a workaround, a quick-and-dirty solution, a clumsy, inelegant, difficult to extend, hard to maintain yet effective and quick solution to a problem, and a rough synonym to the terms "jury rig", "Jugaad" or "jerry rig". HAha, hehe Exactly!  |
|
|
|
Post by gator7 on Jan 9, 2013 11:09:28 GMT -5
Going back to the off Freq on SSB with Galaxy's, my 98 VHP must have been a rare one. It was on freq, but my buddy's 98 was not.  That seems to run true with most Galaxy radios. To bad. And the omega force seems to be a much better radio for a lot less $. If I was going to buy another 10 meter rig. It would be a Omega Force. 73's |
|
?). 
