Yup. D104M6's are notorious for RF feedback. The ferrite choke usually stops that. The Night Eagle and other desk D104's are made of steel and are shielded.
Careful antenna placement and mounting is crucial here.
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2970N2 Strange Problem
- Thread starter Mudfoot
- Start date
Careful antenna placement and mounting is crucial here.
My rig may have had the transmitter section aligned, but I don't think the receiver was touched.
Just talked to a guy about 8 miles from me. He has a new 2970N2 and is suffering from the same goofy SWR problem.
He just said his is "real touchy on the SWR's". He got his new from the eBay seller in Michigan. Came stock with the e-chip in the bag.
I wish I would have kept my green screen N2, never had any issues with it. I haven't called Ranger yet, but wonder what they can do do fix this issue.
He just said his is "real touchy on the SWR's". He got his new from the eBay seller in Michigan. Came stock with the e-chip in the bag.
I wish I would have kept my green screen N2, never had any issues with it. I haven't called Ranger yet, but wonder what they can do do fix this issue.
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Exactly. Sounds like something in the final stage is taking off. With a dummy load you have both a pure 50 ohm load and zero reactance. Any reactive component in an antenna can induce a spurious emmision from the finals. Tuning is critical in this case, and you don't want the final coils to be peaked tuned.
Peak tuning sharpens up Q. Tight Q induces the final stage and tank to take off, to oscillate, often at a harmonic, or at very least some frequency outside your normal SWR range. Thus, you see SWR because the spur is outside your normal tuning range. To cure this, the transmitter tank coils must be slightly detuned. This goes against the grain of typical (i.e.: inexperienced) technician. (I will leave "incompetent" for others to judge).
Sounds reasonable to me. I just got it all packed up. Going to call Monday to get RA#.
Gonna tell them I don't want it back until it works like it should. I don't know if DTB hooks his rigs to an antenna, If not, he should start. It could have saved me some money, time and a big headache.
BTW, I took it to a friends house and hooked it up to his dipole. It did the same thing there.
I'll post the results in a few weeks or earlier. I'll mention your assessment.
Gonna tell them I don't want it back until it works like it should. I don't know if DTB hooks his rigs to an antenna, If not, he should start. It could have saved me some money, time and a big headache.
BTW, I took it to a friends house and hooked it up to his dipole. It did the same thing there.
I'll post the results in a few weeks or earlier. I'll mention your assessment.
The use of a spectrum analyzer is mandatory in cases like this. We used to use a small tuner into the dummy load to create false reactive loads. We also used a standard antenna for whatever frequency the radio was designed for. We had VHF radios that would go spurious at the drop of a hat, (Sonar VHF radios). We used to joke that you knew the radio was properly tuned when it stopped floating above the bench.
Good luck.
Good luck.
The sad thing is this is a faulty power amp design from the factory that is now being pushed on to the field service tech. 90% of them will fail to correctly fix this problem. They'll turn the bias down, detune an RF stage and as soon as they find a condition that it works correct in, send it out the door and hope your conditions match close enough the problem hides itself.
This won't go away until they stop using power supply transistors as RF output devices at 30 MHz. Ever wonder why real high power RF transistors have wide gold plated tabs and the ground connection is doubled? If you can't keep the emitter or drain terminal completely RF grounded trough low inductance terminals, forget about achieving stability at these frequencies.
Many years ago when Motorola designed the 40 watt MRF-477 transistor in this style case, they ran into the same problem. That's why they modified the case so that the metal mounting tab was tied to the grounded emitter connection. Allowing it to be directly grounded without an insulator. They didn't even do that with the higher power MOSFET's in these amps. Very poor design that is now haunting them.
This won't go away until they stop using power supply transistors as RF output devices at 30 MHz. Ever wonder why real high power RF transistors have wide gold plated tabs and the ground connection is doubled? If you can't keep the emitter or drain terminal completely RF grounded trough low inductance terminals, forget about achieving stability at these frequencies.
Many years ago when Motorola designed the 40 watt MRF-477 transistor in this style case, they ran into the same problem. That's why they modified the case so that the metal mounting tab was tied to the grounded emitter connection. Allowing it to be directly grounded without an insulator. They didn't even do that with the higher power MOSFET's in these amps. Very poor design that is now haunting them.
Is Radio Shop Supply a good place to request Ranger radio warranty service from?
Trying to ensure my N2 is worked on by an experienced tech. Not in the mood to play... sending it back and forth with some half assed shop.
Trying to ensure my N2 is worked on by an experienced tech. Not in the mood to play... sending it back and forth with some half assed shop.
I believe they are the recommended repair service for Ranger products.
RADIOSHOPSUPPLY said:
Had a forum member advise that they are hit and miss.
I'm going to see whom all does warranty repair for them. I liked the one guy south of Chicago, (can't remember his name, but he worked for dynascan) he's been at it for a long time.
This purchase is starting to annoy me.
I'm going to see whom all does warranty repair for them. I liked the one guy south of Chicago, (can't remember his name, but he worked for dynascan) he's been at it for a long time.
This purchase is starting to annoy me.
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Talked to Chip @ Radio Shop Supply today. He said he hasn't heard of this issue yet. Said amp stage has been the same design for long time.
He also mentioned that the issue should have shown up on a dummy load. He also stated that during their checks, they put the radio under a 2.0:1 load.
I told him that all of my other radio's (and I have a rather large assortment) and my two solid state amps all act normal on my Gainmaster and my dipole. Even my recent Palomar 450 FET showed a flat SWR on the output end. However, it had a crappy input match.
What else could possibly cause the high SWR on transmission into a nicely resonant antenna system?
I could speculate all day long. It's also strange that a local (whom I don't know) was reporting a finicky SWR with his recently purchased N2.
Could be a production run hiccup.
He also mentioned that the issue should have shown up on a dummy load. He also stated that during their checks, they put the radio under a 2.0:1 load.
I told him that all of my other radio's (and I have a rather large assortment) and my two solid state amps all act normal on my Gainmaster and my dipole. Even my recent Palomar 450 FET showed a flat SWR on the output end. However, it had a crappy input match.
What else could possibly cause the high SWR on transmission into a nicely resonant antenna system?
I could speculate all day long. It's also strange that a local (whom I don't know) was reporting a finicky SWR with his recently purchased N2.
Could be a production run hiccup.