Sunday 2 February 2020

PA for 70 cm transverter

From BG7SGM, I ordered a PA module for 70 cm:
It is capable of delivering appr. 20 Watts RF at 70 cm. The module uses a M57704H.

I installed the module in the 28 - 432 MHz transverter:



A good heatsink is required. For the first time I used the repeater shift mode of the FT450. For 70 cm repeaters, in The Netherlands the repeater shift is 1.6 MHz. I also had to insert the CTCSS frequency of 88.5 Hz. I made a short QSO with PA0WBS via the Rotterdam repeater (430.300 MHz out). 


A quick measurement showed that the transverter delivered 15 Watts RF. Now, the challenge is to work in digimodes and see what is possible (FT-8 in particular).

See bg7sgm.taobao.com  and eBay for more RF products from BG7SGM (use google translate!).


7 comments:

  1. Hi Ron.
    Do you have a schematic diagram of this board.
    If you can, send the private sp4r@wp.pl
    Thanks - Andy SP4R

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  2. Also looking for scheme for this china board. Please send me if possible to ew8ax@ya.ru. Thanks!

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  3. I have a 10×10 board for inlay of the transverter-store.com boards. My idea was to do something similar for the bg7sgm boards. But then for different bands 4m/6m/8m with fet's

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  4. I'd also test the printboard with both relays, with Mitsubishi modules like RA30H4047M and then, the RA60H3847M1. First of all, obliged to change the otuput relay because its NC contact did still remain open
    Then my tests did give followings : excited à 432 MHz with a Marconi 2031 synthesizer (dB/dB up to +15dBm), the 30W module didn't give more than 18W, and the 60W module, not more than 40W ! Unsoldering both relays, then strapping the print did give far better results, but not the wanted 30W (or 60W). But an other print from F3YX does perfectly give the good results predicated from their datas (but without any micro-relay) ! !
    So I am also interested by its schematicn because the 10 turns helipot output is not restricted to the max +6V allowed on Vbase !

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  5. And the rule of Q2 (LM317) is whell understood (basis bias), but what is the exact utility of Q3 theorically a P-Mosfet ? ?

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  6. I just did the complete schematic of this printboard. Also I'd restrict the 10 turns pot to a 6V excursion, by putting a 1.2kR in parallel to it
    And this board, especially its output relay is not intended for an output power of more than 20W ! !
    Any1 interested, pse mail to F5DQK at orange dot fr ! !

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    Replies
    1. Thank you for your comments, merci beaucoup, 73

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