Re: TPL Amplifier model 3010


Carl Beaudry
 

Thank’s Dan for the sugestions.

 

I will give a try to RF Patrs.

 

Best 73

Carl

VA2CMB

 

De : repeater-builder@groups.io [mailto:repeater-builder@groups.io] De la part de Dan Woodie
Envoyé : 20 avril 2020 01:27
À : repeater-builder@groups.io
Objet : Re: [repeater-builder] TPL Amplifier model 3010

 

Skipp, 

 

I was kind of suspecting the same thing about TPL being out of business but I hadn't seen anyone talking about it.  It seems they just kind of vanished.

 

I can guess that one of several reasons was lack of quality control.  A few years ago I picked up a handful of VHF 75W in 250W out TPL amps that were NOS.  The first one worked just fine and I was able to optimize it for the frequency where I would be using it.  When I opened up the second one to start the same process to tune it up as a spare I found that though the boards were installed in an identical manner the cabling was a bit wonky in the second one.  After some side-by-side comparison I determined that the gozinta and gozouta (technical terms) on the RF Sense/matching board were cabled in reverse which means the amp would never key on RF Sense because the input power would not be passed to the RF sense circuit.  I carefully re-routed the cabling and made it identical to the first unit and was able to get it working to factory specs.

 

So that makes you wonder how it passed the QC checks before shipping, doesn't it?

 

Unfortunately for all of their troubles TE actually made decent amplifiers that were easy to work on.  TE Systems are great also but I have seen my share of failures with those as well.  Crescend amps work well as long as you drive them with the EXACT power and frequency they are designed for and keep a low VSWR on the output at all times.  Unfortunately Crescend is not all that friendly to hams unless you are going to buy a new amp at full retail.

 

All of this does bring up a point (which is not necessarily aimed at this particular thread).  It seems like folks are obsessed with running lots of power.  The problem with that is although the numbers seem big remember that for every doubling of power it only gives you 3 dB of OUTBOUND gain while likely effectively decreasing your INBOUND gain by raising the noise floor due to desense or wideband noise caused by PIM or other sources.  The more power you run the harder it is on everything in your signal chain and you have to make sure everything is rated for the increased power.  A much more effective way to increase your coverage is to use antenna gain or better heliax to decrease feedline losses (which can help inbound and outbound signals by changing one run of coax or one antenna if running duplex on a single antenna).

 

The TPL 3010 that is part of this discussion is not really applicable to this since it is a low-drive mid-power amp.

 

As far as finding transistors for that amp I would contact RF Parts.  They seem to have some pretty good cross-references and even if they don't have the parts you need they might be able to send you down the path to what you need.

 

Thanks,

 

Dan Woodie, CETsr

KC8ZUM

 

On Mon, Apr 20, 2020, 12:27 AM skipp025 via groups.io <skipp025=yahoo.com@groups.io> wrote:

> On Sun, Apr 19, 2020 at 06:48 PM, Carl Beaudry wrote:
> Hi to All, I wiill reformulate my search…   Anybody in the group have a
> suggestion of a  commun RF transistor to replace my SRF772 (Flenge
> Mount) in my TPL VHF Amplifier.  Best 73 to all. Carl   VA2CMB

Hello Carl (and the Group)....  Carl, until now I haven't written much about
your amplifier information request because the answer can get quite involved
and time consuming. But since you've been so sincerely working hard on your
repeater and link project... I'll be happy to try and help you with some information
and silly jokes.

TPL made a lot of amplfiiers through the decades they were in business. I
suspect they are now out of business, but that's another thread to later talk
about. Some of the Group Members have a lot experience with RF Amplfiers,
a number of those members chat in direct Emails because they don't want to fill
up the group with more than the normal noise (talk).  We do have some RF
Amplifier archives that are not (yet) available on line (that I know about), but
they could be made available if someone needed a related diagram.

A well informed friend once told me the story of the SRF transistor part numbers,
I could ask him again about it, but it's not that important really. The SRF RF
transistor part numbers were a "house" or specific source (or supply) that were
provided by Motorola (I believe)... many decades back. There have been MRF and
SRF cross reference tables listed in some data books, sometimes even those number
and cross lists are not exact or complete for all the devices made.

Many TPL RF Amplifiers are pretty generic and the older ones do follow common PC
board, circuit design, layout, construction and popular part values for the era of when
the amplifier was made.  Even with a basic amplifier, there were a fair amount of
different options that were offered... Transmit/Receive Switching Relays, Diode TR
Switching, Linear Operation (bias the transistor for AB operation) and the traditional
Class-C FM (and some digital) modes.

Circuit layout wise, you can have a single transistor "device" or "single stage" amplfier, then
two or more devices in series, parallel, then series-parallel combinations and some
rather interesting power combiner / distribution systems (networks). TPL combined
RF amplifier power both on the PC board traces, through hybrids and through a
network I forget the name of... Jeff likes that particular combiner and can probably
better provide the label and a description for it.  There are also single and multiple
device amplifiers in a modular or "pallet" for construction style.

So, probably the best thing to now do, is to take a few very well lighted inside views
of your amplifier, showing the circuit board layout... Then post those pictures here
(or Email them direct to me) and I'll tell you all about the amplifier, probably come up
with some very usable information, a similar or same schematic... or something that
will work fine for repairing your amplifier.  Coming up with a workable transistor part number
shouldn't be that big of a deal, I might even locate one I could send you (not promising
anything fast or for sure).  One member of Junk Enders 12 Step Program, Left Coast
Division was a long time TPL RF Amplifier Service Station, so there's probably not a
lot of models he/she/stray-cats hasn't seen up close.

Get us some pictures... we'll get your car push started.. 

cheers,

Horrendo Revolver


>>  Hi have a Defect TPL VHF Amplifier model 3010.  This seam to be a non
>> standard TPL product…  The specs are 136-174 Mhz FM 13.8 Volts 8W In
>> and 60W out.  I have located the problem to be the RF Final transistor but this
>> also a non standard Motorola transistor… (SRF772).  I have a manuel of a similar
>> model from R/B site   Is there anybody that have a similar Amplifier or info and
>> have a standard transistor model that is still available?  Thank’s to all in
>> advance! Best 73 Carl  VA2CMB

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