Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Mirage B1016 amp question. (Long post, sorry)  (Read 562 times)
N4UE
Member

Posts: 927




Ignore
« on: May 19, 2019, 02:13:06 PM »

Hi gang. I thought I'd ask here instead of the "Amplifier" Forum...…

I have just installed my Icom 9700. It replaced a 271A/471A pair, which were still mint, but getting old, like me. ha ha

I have the original Mirage B1016. I've had it for decades. I 'tuned' it, so it used to produce just shy of 200 watts into my Cantenna. I added a big muffin fan over the heatsink, and it's been rock solid. Never got hot.

As you may know, one of the 9700's 'warts', is it's single RCA connector to key an external amp.
I built a simple 'switch box' with toggle switches/LEDs to allow switching between the Mirage and my THP 70CM amp. It uses the DIN connector on the 9700 for the key line and also for +12VDC. The 9700 picks a small relay, which I can select which amp I want to key. Don't have 23CM, so for now it's just for 2M and 70CM.
Turning down the 9700 to 10 Watts, allows the Mirage to produce it's somewhat reduced output. I can't go QRO, due to my mast mounted GaAsFET specs. I have a Bird 43 to measure output power.

It works great with one issue:

The Mirage uses what appears to be RF sensing when turned 'on'. Not really described in any info I've found. So, even though my little external box does not send a ground shot to the Mirage, it keys anyway. I've tried turning the 'sensitivity' control on the side of the amp, but at about 10 watts, the Mirage chatters.
I know I could just switch the amp off, but that's adding another step when switching from 2M to 70CM. When the amp is 'off', I'd have to bump the 9700 power out to max. more actions than I want to do. Especially if I forget to turn the 9700 back to 10 watts and turn the Mirage on.
BTW, my Bird with the correct VHF slug, indicates exactly 100W out of the 9700 on 2M. cool

I have the Mirage Manual 'somewhere', so I downloaded the 1984 schematic from the web.

Any suggestions before I start surgery?? Huh

ron
N4UE



Logged

If you're not the lead sled dog, the view never changes......
K4JJL
Member

Posts: 1126




Ignore
« Reply #1 on: May 20, 2019, 06:06:20 AM »

There's probably a way to disable the RF sensing by pulling one of a dozen parts out.  Easiest is probably the 1N6263 Schottky diodes.

The "sensitivity" knob is actually a delay adjustment for the SSB function.

Here's the schematic and info...

https://www.qsl.net/wb4kdi/Mirage/index.html

If you decide to disable the RF sensing, you'll have to make absolute sure that you have the pre-amp turned off if you run it without the keying line.  It will smoke the GaAsFET.
Logged
VE6MB
Member

Posts: 31




Ignore
« Reply #2 on: May 20, 2019, 09:26:01 AM »

I can't speak for Mirage amps.....but in some amps (like TE systems), when you use the hard-key option....you operate the amplifier with the mode switch in FM mode.

Tino, VE6MB
Logged
N4UE
Member

Posts: 927




Ignore
« Reply #3 on: May 20, 2019, 01:38:35 PM »

There's probably a way to disable the RF sensing by pulling one of a dozen parts out.  Easiest is probably the 1N6263 Schottky diodes.

The "sensitivity" knob is actually a delay adjustment for the SSB function.

Here's the schematic and info...

https://www.qsl.net/wb4kdi/Mirage/index.html

If you decide to disable the RF sensing, you'll have to make absolute sure that you have the pre-amp turned off if you run it without the keying line.  It will smoke the GaAsFET.

John, thank you for the reply. I had not considered the preamp being damaged. More than likely, I won't need the Mirage preamp as the 9700 has great sensitivity and if needed, I have a mast mounted GaAsFET way up in the air.

thanks again!

ron
N4UE
Logged

If you're not the lead sled dog, the view never changes......
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!