Mr TO there is a very important rule to those type of amplifiers they are transistor based amplifiers If one of those transistors is shorted or happens to short while running it will absolutley KILL your radios MOSFET final. RM Italy makes a MOSFET amplifier instead of a transistor type amp MOSFET amps wont Burn your finals in your radio if they short. Just a warning while using that style of amplifier on a very expensive ICOM or yaesu radio. Great video.
I have fixed many of them over the years. Lots of different finals can be used. some tuning and rewinding RF transformers needed. SD1446 transistors work nice, when tuned out. does about 125W PEP with 4 to 5 watt drive. You need a true PEP meter to show better power. They are dirty and need band pass filter. Back in the day we put 12V PC fan on heat sink and talk longer. Just don't talk long with car not running. Palomar had tube ones out as well. still got some but only one working. Blue 300A Tube one still works. RM Italy still makes small amps today ! nice 100 watt FET amp. 160 to 6 meters and has band pass filters . about same size at that old one. 73's
Steve, Looking at the schematic...I see no idle bias circuit for the finals, so it really can only be used for AM. On SSB, it will have more spurs than a good old Western movie. It could be modified for 80-10M with a somewhat decent output, but in its current configuration will really only provide the correct impedance to the finals at 12-10M. Those broadband transformers don't have enough inductance for 20M and lower, so there is a giant impedance mismatch and that's why you have almost no power on those lower bands. If you do the 2 mods I mentioned (idle bias & transformer replacement), the last issue will be that of DC power starvation. The wire gauge is far too small, so change that out with the correct colors and 12ga wire. Next, I would install a cap inside where the power comes in. I recommend a 450uF or larger at 25V. This will help to smooth out the current requirements on PEP-SSB. It will do nothing on AM. Lastly (I used to do this for all my customers mobile installations), add a jack for a PTT line to bypass the RF relay keying circuit. This will allow the amp to key in sync with the rig when the mic is keyed even if there is no RF output from the rig. SSB operation benefits greatly from this mod, but all the mods need to be done in the order presented. 2nd harmonics are generally not too bad because this is a "push pull" amplifier, and that's the nature of any amp with that design. It's the 3rd harmonic that will present issues, and a LPF will need to be added on the output line to tame it. If you need any help, you know how to contact me. This could be a nice little amp for a QRP rig, but it must be cleaned up first. 73 OM.
I got the impression this was a CB only amp from the googling I did. I found it interesting that it was labeled 3-30, but only really worked on 7-30... And as you said 10-11-12 is where it's best. Fun to play with for sure.
Too cool. I work for AMF (AMF Bakery Systems) as a Controls Engineer/MIS Engineer. I'm located in Richmond, VA HQ. Now the company makes large Industrial Bread/Bun baking and handling equipment. AMF is not longer associated with the bowling side. Yea, AMF has done a ton of things in the past.
Hot dang, an oldie but goodie. It was made in the mid 1970's before the FCC banned them. You might want to check some vintage Allied Radio and Lafayette Radio catalogs, they might have been sold there.
i have a few of these in my 11-meter collection, the tx 100 should key around 50-60 watts with a 1-watt dead key and swing around 150-175 watts pep provided the radio can swing (i don't think a HF radio can swing on am). i would suggest replacing the transistors with some HG 2SC2290 60-watt transistors from ica manufacturing and be sure to replace the electrolytic capacitors.
I saw no low pass filters in the box. Was that correct? Without those for each band you risk emitting out of band signals. Does the AM modulate downwards directly from the X6200? If it is upward modulating and the amp inverts you might look at the bias setting on the transistors when the amp is switched to AM. I was surprised to see this work on 7MHz CB amps normally only work from 20-30 MHz. Cheers Ed.
zero filters! I was surprised when it said 3-30 and only worked on 7-30... and then in reality (as you saw) it really worked well on 10-11-12 - Fun stuff playing with old tech!
@@temporarilyoffline as you say this is an old amp but very similar amplifiers are still available. Similar design, similar frequency range. Take a look at the cheaper RM Italy amps for example. 73 Ed.
That is a "good buddy box". I wouldn't let that thing near my hf rig. They put 3-30 mhz on it in a desperate attempt to get past the FCC. It needs to have a filter board to be a ham's amp.
Mr TO there is a very important rule to those type of amplifiers they are transistor based amplifiers If one of those transistors is shorted or happens to short while running it will absolutley KILL your radios MOSFET final. RM Italy makes a MOSFET amplifier instead of a transistor type amp MOSFET amps wont Burn your finals in your radio if they short. Just a warning while using that style of amplifier on a very expensive ICOM or yaesu radio. Great video.
Thanks for the tip! All amps should have a PTT circuit (and all radios should have a TX delay)
I have fixed many of them over the years. Lots of different finals can be used. some tuning and rewinding RF transformers needed. SD1446 transistors work nice, when tuned out. does about 125W PEP with 4 to 5 watt drive. You need a true PEP meter to show better power. They are dirty and need band pass filter. Back in the day we put 12V PC fan on heat sink and talk longer. Just don't talk long with car not running. Palomar had tube ones out as well. still got some but only one working. Blue 300A Tube one still works. RM Italy still makes small amps today ! nice 100 watt FET amp. 160 to 6 meters and has band pass filters . about same size at that old one. 73's
So many ways to stack forward with this old amp!
Steve, Looking at the schematic...I see no idle bias circuit for the finals, so it really can only be used for AM. On SSB, it will have more spurs than a good old Western movie. It could be modified for 80-10M with a somewhat decent output, but in its current configuration will really only provide the correct impedance to the finals at 12-10M. Those broadband transformers don't have enough inductance for 20M and lower, so there is a giant impedance mismatch and that's why you have almost no power on those lower bands.
If you do the 2 mods I mentioned (idle bias & transformer replacement), the last issue will be that of DC power starvation. The wire gauge is far too small, so change that out with the correct colors and 12ga wire. Next, I would install a cap inside where the power comes in. I recommend a 450uF or larger at 25V. This will help to smooth out the current requirements on PEP-SSB. It will do nothing on AM. Lastly (I used to do this for all my customers mobile installations), add a jack for a PTT line to bypass the RF relay keying circuit. This will allow the amp to key in sync with the rig when the mic is keyed even if there is no RF output from the rig. SSB operation benefits greatly from this mod, but all the mods need to be done in the order presented. 2nd harmonics are generally not too bad because this is a "push pull" amplifier, and that's the nature of any amp with that design. It's the 3rd harmonic that will present issues, and a LPF will need to be added on the output line to tame it. If you need any help, you know how to contact me. This could be a nice little amp for a QRP rig, but it must be cleaned up first. 73 OM.
I got the impression this was a CB only amp from the googling I did. I found it interesting that it was labeled 3-30, but only really worked on 7-30... And as you said 10-11-12 is where it's best. Fun to play with for sure.
Too cool. I work for AMF (AMF Bakery Systems) as a Controls Engineer/MIS Engineer. I'm located in Richmond, VA HQ. Now the company makes large Industrial Bread/Bun baking and handling equipment. AMF is not longer associated with the bowling side. Yea, AMF has done a ton of things in the past.
That's awesome! Good to hear they are still atound
I love the figuring it out live videos
Thanks, I like to share them - helps us all out a bit.
You always make the best videos Man cheers
Thanks Ziggy! These are fun to do. I love playing with tech.
Try your thermal camera, Steve. Quick way to see if both pills are equal and reactive.
#ProTip thanks!
EXCELLENT suggestion!
I have that amps little brother, the TX75. It was my dad’s in the mid 70’s.
Sweet! Its fun to play with for sure!
Hot dang, an oldie but goodie. It was made in the mid 1970's before the FCC banned them. You might want to check some vintage Allied Radio and Lafayette Radio catalogs, they might have been sold there.
Banned is such a harsh word! We are hams, we can make it all better
Those amps work great on CB band. I never put mine on any other meters. You should try that.
Good idea!
i have a few of these in my 11-meter collection, the tx 100 should key around 50-60 watts with a 1-watt dead key and swing around 150-175 watts pep provided the radio can swing (i don't think a HF radio can swing on am). i would suggest replacing the transistors with some HG 2SC2290 60-watt transistors from ica manufacturing and be sure to replace the electrolytic capacitors.
Good tips, thanks!
11 meters World Wide! :) Stay Awesome!
World Wide, World Wide!
I saw no low pass filters in the box. Was that correct? Without those for each band you risk emitting out of band signals.
Does the AM modulate downwards directly from the X6200? If it is upward modulating and the amp inverts you might look at the bias setting on the transistors when the amp is switched to AM. I was surprised to see this work on 7MHz CB amps normally only work from 20-30 MHz.
Cheers Ed.
zero filters! I was surprised when it said 3-30 and only worked on 7-30... and then in reality (as you saw) it really worked well on 10-11-12 - Fun stuff playing with old tech!
@@temporarilyoffline as you say this is an old amp but very similar amplifiers are still available. Similar design, similar frequency range. Take a look at the cheaper RM Italy amps for example. 73 Ed.
@@DD5LP agreed, there are even some amp kits on eBay that look like this
thank you
You're welcome
I have a Pal 200MDX that I've never put power to. I think maybe I should open it up. Thanks👍
Would be fun to play with!
That is a "good buddy box". I wouldn't let that thing near my hf rig. They put 3-30 mhz on it in a desperate attempt to get past the FCC. It needs to have a filter board to be a ham's amp.
You're absolutely correct. Its an interesting amp for sure.
Nice work, tnx Man!
You bet! Thanks for watching!
Didn't AMF own Harley Davidson for a bit?
Sure did
This amplifier leaks oil. 🤣
Engage!
Warp Factor 5!