Topic: Help Converting 10 Meter Amp to work on 6 Meters (Read 11587 times)

W7TZG · « **on:** May 02, 2008, 09:31:03 AM »

I have a 10 meter Amp Pal BDX 351 TRU Bi Linear, sold for 10 Meters ,We all know they were sold as 10 Meter Amps but were for 11 Meters also. wonder if any one would know How to confert this Amp to work on 6 Meters, uses 4 8950 Tubes. Thanks .

KB9CRY · « **Reply #1 on:** May 02, 2008, 04:18:38 PM »

Pal 351 Box
Tru-Bi Linear Base
(500 Watts)
Function: am/ssb/base/xmit/rec on
/Hi/ssb/standby/off/lo/am
Ant-Plate
13.8vdc

It's an illegal CB amp for 10 meters.

W7TZG · « **Reply #2 on:** May 02, 2008, 05:17:28 PM »

Why is it illegal for 10 meters???

WB2WIK · « **Reply #3 on:** May 02, 2008, 07:10:08 PM »

I can answer that: It's illegal for 10 meters because FCC CFR 47 Part 97 requires certification for amplifiers in the HF spectrum.

If the amplifier is not certificated, it's not legal to sell in the U.S.

It is still legal to "homebrew" amplifiers for amateur radio service, with the provision that the builder/user agrees to meet the spectral purity requirements in the Technical Standards of Part 97.

Unfortunately, this amplifier does not, unless someone specifically modifies it to do so and then takes data on the results, which he could provide to an inspector upon request.

The real problem is that amplifier is not legal to "sell" in the U.S., for any purpose, because it's not certificated.

WB2WIK/6

G8UBJ · « **Reply #4 on:** May 05, 2008, 12:54:40 AM »

I'm not sure about the US but in the UK any equipment is fair game for modification on the Amateur bands (So long as its not stolen or something).
A class A or full licence enables the operator to build or modify equipment.

One purpose of our licence is to encourage experimentation and increase our technical level of expertise, not just buy a box and go on the air; thats what CB is for!
Nobody expects us to have expensive test equipment and in the past most of us got by with an absobtion wavemeter (Measure harmonics) valve or digital voltmeter, GDO and an SWR bridge.
So long as you have this basic equipment (or can loan it) you are good to go. Either draw out the circuit and lookup the data on the components, or if a mod exists follow it. If you do the former document it and put it on the web with advise (So others can benefit.)
On the other hand if your US licence doesn't permit experimentation chuck the amp in the bin with it!

73 and see you on 6M (Better still work me cross bands on 4M, I run a 150 watt CB amp modified for 70 Mhz
G8UBJ

W8JI · « **Reply #5 on:** May 05, 2008, 06:29:33 AM »

All that aside, you will have a tough time getting 4 8950 tubes to work on six meters.

It also might not be very clean for splatter if you do get it working.

I'd use something different for six.

73 TTom

WB2WIK · « **Reply #6 on:** May 05, 2008, 11:07:21 AM »

I also doubt you'd have much luck with four paralleled 8950s on 50 MHz.

One or two might work, however.

Drake had three paralleled sweep tubes in the TR-6 (vintage 1970) and got that to work, but those were somewhat smaller than 8950s. You might download the TR-6 schematic, see what they did, and copy it!

WB2WIK/6

W7TZG · « **Reply #7 on:** May 10, 2008, 10:16:47 AM »

Thanks Tom.
I Have read all the Comments on the conversion of this Pal Amp.
to be sure I know all one has to do to get it to work on 6 meters, is to rework the (2) coils, and be sure to stay in guide lines of Part 97 and (15)..AS ANY GOOD "OLD" Ham will DO....
To be sure we all know there OR at least used to be many Hams that spent many hours ,"""HAVING' a Grand time just working different circuits, and we all know some worked, and some "Smoked".. "But we Learned",, and when one would ask for help, most if not all who knew there was a need for Help. would be there,
It's a SAD time we live in today, in the Ham community, where it's easer to critize and scold, instead of helping, BUT I will certainly ADD THIS, In my Openion those thet are there and have been there are the "Elmers" of long ago that "OFFER the HELP) and as you did offer incourgement, not critize,

Just an OLD HAM...
Thanks
Jim W7TZG...

W7TZG · « **Reply #8 on:** May 10, 2008, 10:26:13 AM »

Tom .
Thanks for the input. and as stated in another answer to my search for Help.
Thanks for being an Elmer....

Jim W7TZG

W7TZG · « **Reply #9 on:** May 10, 2008, 10:30:42 AM »

WB2WIK,
Thanks for the input...
All you stated is correct, Know and follow part 97 and 15. to the letter Huummm. Which all Amateurs Should do .

W7TZG,,

W7TZG · « **Reply #10 on:** May 10, 2008, 10:32:39 AM »

KB9CRY
Thanks for the advice...
Part 97 and 15 covers this very Well as we all should know,, Right...

W7TZG

KM3F · « **Reply #11 on:** September 19, 2008, 12:54:57 AM »

I know this thread is old but you should know that 4 large tubes of this type present a lot of capacitance to ground and inter electrode capacitaence hence is not good for vhf operation because the plate and electrode structure is to large and the base leads to long..
The capacity required in the output tank circuit is often less that the tubes provide hence the efficiency is reduced and the tubes are to large a part of the overall tuned circuit.
Take a look at the spec on this tube for max usable frequency for a single tube.

Author Topic: Help Converting 10 Meter Amp to work on 6 Meters (Read 11587 times)